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Post Title: 94 240 conv with AT shift problems Posted by:oldbald_sarge at 6:39 PM 1/4/2005 My 94 has intermittent shift problems. Seems she doesn't always want to upshift. Have to turn her off, restart, wait for the idle to drop to about 650 (ingear), and then she goes OK for a while. Is this a common problem with these cars? Other than that, she's my pride and joy. Had my mechanic look at it and he suggested some sensors/switches replacements. Hasn't helped yet. Help, please...
Post Title: Posted by:AZhitman at 7:30 AM 1/5/2005 Common problem with S13 autotrans. Seems to be worse in convertibles.
I did a pan drop, filter change and new fluid (with a bottle of LucasOil trans treatment) and it seemed to make a big difference.
Make sure to clean out the pan and remove the magnet and clean it well.
Post Title: Re: (AZhitman) Posted by:oldbald_sarge at 8:28 AM 2/5/2005
"seemed to make a difference" to what degree? Sometimes she runs like a dream, and sometimes more of a nightmare. No rhyme or reason, either. Has your transmission problem been fixed, or is it now more or less acceptable? Thanks for answering and giving me some help and options.
Post Title: Posted by:AZhitman at 10:03 AM 2/5/2005 Nope, I spoke too soon.
It accomplished nothing.
Mine slips approx 10 minutes into driving it (from a cold start), and once it quits slipping, it drives fine (until it gets cold again, then starts all over again).
Pulling the autotrans for a manual swap in 2 weeks, auto rebuild too expensive.
Post Title: Re: (AZhitman) Posted by:oldbald_sarge at 1:02 PM 2/5/2005
Are you going to do the swap yourself, or are you going to hire someone? Let me know how that went.
Post Title: Posted by:AZhitman at 8:31 PM 2/5/2005 Having the local guys over to help.
We have some great "tech days"!
Post Title: Re: (AZhitman) Posted by:Eikon at 10:09 PM 2/5/2005
Hey AZ..
I know it's a lot of work.. but it would be very cool if you did a pictoral how-to guide for everyone else to follow in the future. I have seen other's do bits and pieces with pics, but never a real good step by step tranny swap guide.
just an idea.
Good luck with the swap. Nice to see another SHIFT---Convertible around.
Post Title: Re: 94 240 conv with AT shift problems (oldbald_sarge) Posted by:2the40 at 9:03 AM 2/6/2005
Quote, originally posted by oldbald_sarge »
My 94 has intermittent shift problems. Seems she doesn't always want to upshift. Have to turn her off, restart, wait for the idle to drop to about 650 (ingear), and then she goes OK for a while. Is this a common problem with these cars? Other than that, she's my pride and joy. Had my mechanic look at it and he suggested some sensors/switches replacements. Hasn't helped yet. Help, please...
I have a HB and it doess the exact same thing. Myself and others have been trying to figure it out on the tech. fourms but we have come up with little. We think it is electrical most likely a short or bad sensor. I don't think anyone has yet to figure it out, but the throtle positioning sensor and speed sensor might be part of the problem. Good luck!
Post Title: Re: (AZhitman) Posted by:ncaa1969 at 5:08 PM 2/8/2005
Same problem and symptoms here with 92 240 Conv. Only happens in a brief period about 7 to 10 minutes after a cold start or right away if the car has been shut down for about 20 minutes. Turning the key on and off clears it. I was thinking it was electrical but also have had the car drop back into and stay in first if I hit a sharp bump when just starting during that warming up period. But, if I start out real slowly it may not stick.
Throttle position switch adjusted with minor improvement. Flush improved all other shifting characteristics but hasn't cured the base problem. I'll report any significant progress..........if it occurs.
Post Title: Posted by:AZhitman at 5:15 PM 2/8/2005
Identical to my symptoms.
Down to the exact timing....
Post Title: Re: 94 240 conv with AT shift problems (oldbald_sarge) Posted by:smc2017 at 12:48 PM 2/16/2005
Had the same problem. I knocked a sensor loose when tightning my belts. Searched and searched and couldn't find it. I took it to an auto electric place and they fixed it for $35. I just put the 5 speed in a few months ago because the auto was nothing but problems. good luck.
Post Title: Re: 94 240 conv with AT shift problems (smc2017) Posted by:MrUnderhill at 3:30 PM 2/22/2005 I've got the same problem with my '92 conv with AT (started at about 145,000). I notice the problem after 5 - 10 minutes of driving, and it is always worse in warmer and more humid weather. Usually the problem occurs after waiting at a stop light and the transmission will not shift up. Occasionally the transmission will downshift while driving for no apparent reason and get stuck after that. The only ways I have found to remedy the problem while driving is to 1) stomp on the gas, 2) drive near red-line RPMs until the car shifts, or 3) if I can get the car up to 40 on a downslope the transmission will usually then shift up on its own. Any suggestions on a cheap fix would be most welcome.
Post Title: Posted by:AZhitman at 6:36 PM 2/22/2005 Yep - Same as mine.
I swapped to a 5-speed, thniking I had a bad trans.
Post Title: Re: 94 240 conv with AT shift problems (smc2017) Posted by:240ROCKER at 2:05 PM 2/23/2005
smc2017, When you say that you had a sensor loose and you had an auto electric place fix it for you, did this correct your AT shift problem or did you already have the 5 speed put in it when you had them fix your loose sensor? If this did fix your AT shift problem, which sensor was the culprit?????
I have the exact same problem to the "T" as everyone else here in this forum with this auto tranny! I'll be waiting to hear back from you. Thanks!!!!!
240rocker
Post Title: Re: 94 240 conv with AT shift problems (240ROCKER) Posted by:smc2017 at 5:18 AM 2/25/2005
I said sensor, but I think it was actually a wire into the wire harness. It did fix the shifting problem, but shortly after I ended up with a hard shift problem. Bad solenoids in the tranny were causing that. Fixed that and more crap happened. If you can put in a 5 speed you will be more happy. I did it 5 months ago, and I haven't had to fix anything since.
Post Title: Re: 94 240 conv with AT shift problems (smc2017) Posted by:ncaa1969 at 5:52 PM 2/25/2005 I'm far from ready to declare success, but addition of a bottle of Lubegard has reduced the "hangup in first gear" problem from every trip to once in the last ten days.
Post Title: Re: 94 240 conv with AT shift problems (ncaa1969) Posted by:240ROCKER at 11:09 PM 2/25/2005 OK guys...I am determined to find out why this Auto tranny is behaving in this manner. There are just too many people on here that are having the same problems as we are. Here is what we know so far. The car seems to not want to shift into 2nd gear from first, sometime during the first 20 minutes of driving. It seems to happen more frequently when it's warmer outside and when there seems to be alot of humidity! It seems like the only way to temporarily correct this is to shut the car completely off. However, all we are doing when we do this is resetting the ECU back to default condition. That is why we are able to continue driving without the problem until the next time we drive after letting the car rest for about 20 minutes. I have also put in some tranny additive that is supposed to cool the tranny fluid temperature down about 10°. This worked for about two weeks, then it started happening again. This is definitely a heat/temperature problem based on these symtoms.
This weekend, while driving my car, I'm going to hopefully get the car to exhibit this shift occurence and when it does, I am going to try and get the codes out of my ECU to see where it might be failing.
I have had this problem for about two and a half years now and I have taken it to two different Nissan dealers and of course it wouldn't act up on them so I never got anywhere with them. One dealer did a $160 tranny flush and the other dealer charged me $35 to drive my car for an hour. I had a transmission shop look at it also and it never acted up for him either, but he suggested that maybe the TPS was bad so I replaced that too.
Does anyone here who knows anything about the TCU think that maybe this could be the culprit? I work with electronics everyday and I know how picky some circuits can be when they go thru temperature extremes. What exactly does the TCU do? Does it actually tell the tranny when to shift gears? I found a place in Florida that repairs and sells these for around $250. Someone else also mentioned that maybe the 1st to 2nd solenoid in the tranny could be flaky. I talked to another transmission shop the other day and he told me that if it was the solenoid it wouldn't be bad at all to replace. All you have to do is drop the pan and check the solenoid and replace it if it's bad.
OK guys these are the things that I'm looking at and as I find out more info I'll let you know.
Oh...and I could very easily put a 5-speed in, but I really want to know why this is happening to our Auto tranny's. I am determined to find out.
I'll keep ya posted and anymore info you can offer would be great too!
Thanks!!! 240ROCKER
Post Title: A Question For Those Of You Who Have Had This AT Shift Problem? Posted by:240ROCKER at 8:52 AM 2/28/2005
Have any of you had to replace your radiator before you started having the shift problem? If so, did you buy an OEM or aftermarket radiator?
Post Title: Re: A Question For Those Of You Who Have Had This AT Shift Problem? (240ROCKER) Posted by:smc2017 at 10:07 AM 2/28/2005 I replaced my radiator, but not because of the shift problem. Just bought one at NAPA, was a direct replacement. Make sure you bleed the hell out of it, or you will have overheating up the ***.
Post Title: Re: A Question For Those Of You Who Have Had This AT Shift Problem? (smc2017) Posted by:240ROCKER at 12:38 PM 2/28/2005 Nah...I'm not saying I replaced my radiator due the shift problem. I'm saying that when I had a problem a couple of years ago with my car overheating that I replaced the radiator with an aftermarket one and ever since then I have had this intermittent shift problem! The overheating problem was fixed, but the shift problem was created.!
240ROCKER
Post Title: Has Anyone Red-Lined While Trying To Shift? (240ROCKER) Posted by:240ROCKER at 1:08 PM 2/28/2005
Has anyone who has had this shift problem ever red-lined it to see if it will shift into second?
Another question I have is if I take off manually in first gear will the car automatically shift into second as it approaches red-line even though I'm in first?
Post Title: Posted by:AZhitman at 9:23 PM 2/28/2005
No.
Mine would rev to the rev limiter (I feared damaging the motor).
Manually leaving the car in first will hold it there.
Post Title: Re: Has Anyone Red-Lined While Trying To Shift? (240ROCKER) Posted by:2the40 at 9:24 PM 2/28/2005
I have redlined mine several times seeing if I could get the tranny to shift, but it didn't work. I don't recommend it.
I have been taking mine to shops in my area, but no one knows what is the matter with it.
Recently I had an episode where my car didn't shift. I shut it off and restarted it, but this didn't work. I tried again and got it to shift. Ever since that bad episode it shifts kinda hard and makes a whining noise at low speeds. I am about ready to have the transmission rebuilt. I guess 2 years of this problem has taken it's toll on the car. I wish I could figure it out!
Post Title: Re: 94 240 conv with AT shift problems Posted by:240ROCKER at 7:58 AM 3/1/2005
Well guys I found out something interesting about having your automatic transmission rebuilt. Apparently, when you opt to have your automatic transmission rebuilt, this does not include rebuilding the "valve body" which is the brain of the transmission. Several people have posted on here and on other places on the internet who decided to rebuild their transmissions only to find out that they still had the shift problem. What a bummer to know that you spent all that money for a rebuild and it didn't actually fix the problem.
The valve body has all sorts of control valves and springs and is a very expensive part to replace, which is why most tranny shops don't rebuild or replace these.
I have learned that more than likely I have a stuck control valve in the valve body and the reason that I normally don't have a problem in colder weather (50° or lower) is because there is more pressure being built up in the valve body to compensate for the colder temps. and when it's warmer weather, the pressure isn't as high and therefore one of the control valves that pertains to the 1st to 2nd shift is getting stuck. I was told that an additive called "Transmedic" might unstick this valve. It will take about two to three weeks to really get into the system, but that it might keep that control valve from sticking.
What are your thoughts on this?
240ROCKER
Modified by 240ROCKER at 1:03 PM 3/1/2005
Post Title: Re: 94 240 conv with AT shift problems (240ROCKER) Posted by:2the40 at 4:42 PM 3/1/2005
I haven't heard that before, but it make sense. Thank you for the help.
The thing is, my car repeatively has issues shifting into 4th also.
Is there one valve body, or are there multiple ones that control different trans functions?
Post Title: Re: 94 240 conv with AT shift problems (2the40) Posted by:240ROCKER at 5:49 PM 3/1/2005
There is only one valve body, but there are lots of tiny valves and springs that control the following: Torque Converter relief valve, Pressure regulator valve, Pressure modifier valve, 4-2 Sequence valve, 4-2 relay valve, Overrun clutch control valve, Overrun clutch reducing valve, Shuttle Shift valve, Lock-up control valve, Pilot valve, Accumulator control valve and these are just the valves in the top body of the valve body.
The lower body of the valve body has these valves in it: Servo charger valve, 3-2 timing valve, 1st reducing valve, Manual valve, Modifier accumulator valve. So as you can see there are a bunch of valves in this very intricate part and this is more than likely the cause of our shift problems. One of these valves is getting stuck and not operating properly.
I'm going to try this Transmedic additive made by GUNK and I'm going to see if this fixes my problem. I will give it a few weeks and see what happens.
240ROCKER
Post Title: Re: 94 240 conv with AT shift problems (240ROCKER) Posted by:2the40 at 6:24 PM 3/1/2005
Wow, the valve body does have a lot of parts. I think I will try the additive too.
Thanks for the info!
Post Title: Re: 94 240 conv with AT shift problems (2the40) Posted by:MrUnderhill at 8:49 AM 3/2/2005
I tried Transmedic about 18 months ago and I had the same experience as the person who posted about using Lubeguard - it might have helped for a few days but soon the transmission was up to its old tricks again. I've still got half the bottle on the shelf in the garage, so maybe I didn't get enough into the system, but I didn't have much luck with it as a permanent cure.
I'm curious to know if 240Rocker's ECU codes have yielded any clues as to what the problem(s) might be...
Post Title: Re: 94 240 conv with AT shift problems (MrUnderhill) Posted by:240ROCKER at 11:00 AM 3/2/2005
Well...yesterday the temperature outside was 45° and I had the shift problem while driving. As I have stated earlier that this problem doesn't usually happen in colder weather, but it did yesterday. Anyway, I quickly pulled over to a side street and turned my car off and looked at the ECU code and there wasn't any failure code whatsoever. I had a '55' which is a code for everything is fine!
It is my understanding that you need to pour the entire bottle of Transmedic in your tranny and wait a good two to three weeks to get in your system.
Has anyone used the new Dexron III in their auto tranny's yet? I have also read on other forums that this might possibly fix tranny problems as well. There are so many possible solutions out there. I just wish we could find one that everyone is in agreement with!!!!
I'm still determined to get to the bottom of this!
240ROCKER
Modified by 240ROCKER at 1:10 PM 3/2/2005
Post Title: Re: 94 240 conv with AT shift problems (240ROCKER) Posted by:2the40 at 2:13 PM 3/2/2005
I tried that Dexron III Mercon for my last fluid change. I also used Seafoam Trans Tune just before I changed the fluid and filter. I noticed an incredible difference in shifting for about 20 minutes after, but then it started to screw up again.
The only thing I might have done wrong was not leaving the Seafoam in the transmission long enough.
Post Title: Re: UPDATE: 94 240 conv with AT shift problems (240ROCKER) Posted by:240ROCKER at 7:40 AM 3/11/2005
Here is a little bit of an update on my quest to find out why our auto tranny's are behaving in this manner.
First off, I removed the kick panel so I could get at the ECU so that I could see if it would give me an error code. It did not. It gave me a code of '55', which means no error.
Next, I went and talked to a auto tranny specialist here and we talked about this shift problem in great detail for over an hour. He was very informative. He seems to think that this is definitely an electrical problem and not a mechanical one because of the fact that it always happens during the first 5 to 10 minutes of a cold start.
He advised me to splice an LED on the wire that goes to the Shift solenoid for D1 to D2 (this is pin 6 of the TCU). I believe the service manual calls it Solenoid "A". Tie the other end of the LED to ground. Make the wires long enough for the LED to be in plain site while driving so you can see it for this test.
When the car is operating correctly, and the car is still in first gear the LED will be 'ON' and when it shifts to second gear, the LED should turn 'OFF'. Now, if the car doesn't shift into second and you are above 37 MPH, look at the LED as it should be off. If the LED is 'ON' at this point, then the TCU is bad. If it is 'OFF'and your car hasn't shifted yet into second, then more than likely you will have a bad shift solenoid for D1 to D2.
I told him that I had read that on other forums that replacing the valve body was a fix that some people had tried and worked. He told me that the reason that was probably a fix is because more than likely, when the valve body was replaced, so was the solenoid because it is attached to the valve body.
The reason that we are seeing this intermittent shift occur during the first to second shift interval is because this solenoid is used more than the other solenoids. However, in time the other gears will more than likely behave in this manner, which means that the other solenoids will eventually go bad too.
I haven't hooked up the LED yet. The TCU is a little bit further up in the dash and so I really haven't had time yet to unbolt it from the frame. I'm doing that this weekend, so when I get the results of the LED test I'll let you know. If the LED is 'OFF' and the car doesn't shift, I'm taking the car to my tranny specialist and he is going to remove the D1 to D2 solenoid and test it in a heat exchanger to see if it is operating properly.
I'll let everyone know as soon as I know...!
240ROCKER
Post Title: Re: UPDATE: 94 240 conv with AT shift problems (240ROCKER) Posted by:guyaverage at 12:07 PM 3/11/2005
^^ Great information, definitely let us know what happens.
Post Title: Re: UPDATE: 94 240 conv with AT shift problems (240ROCKER) Posted by:2the40 at 3:31 PM 3/11/2005 240Rocker... you're my favorite.
Great info!
Post Title: Re: UPDATE: 94 240 conv with AT shift problems (240ROCKER) Posted by:ncaa1969 at 2:46 PM 3/12/2005
240Rocker (and all interested parties....) I set up the LED's as recommended. I actually used two, one for Solenoid "A" and one for Solenoid "B".
At startup from cold, the transmission shifted properly and the LED's behaved properly, that is: A+B lit for first gear, B only for second, none for third, and A only for overdrive.
I stopped and started until it hung up in first gear, staying in first all the way to redline (where I backed off) without shifting. During this hangup, both LED's for A+B stayed lit, indicating that the TCU was telling the transmission to stay in first gear.
Unfortunately the hang up only occured once and the next (and all following) stop and start operations shifted normally and the LED's behaved normally. I intend to try this again tomorrow once everything has cooled down. I would like to replicate the "hang up for a while but then shift" pattern I sometimes get.
But by your mechanic's analysis this would point to a bad TCU.
TCU's sound expensive, so there is one more thing I am checking. The transmission has a fluid temperature sensor in the sump, a resistor whose resistance drops as the fluid temperature rises. I measured the resistance when cold (65 degrees in the garage) and it was 2560 ohms versus the manual's standard of 2500 for 68 degrees. I took another reading when warmed up and got about 600 ohms (no range is given in the service manual). I will try to rig up a way to measure this resistance on the fly so I can watch the multimeter to see if the resistance drops smoothly as the fluid warms up. Not sure what I'm looking for but I would certainly expect the change in resistance to be smooth. We'll see.
I sure would like the temperature sensor to be the culprit since it looks cheaper and is easily changed (drop the pan and it is right there.)
I wish I knew the computer logic (how it integrates throttle position, RPM, fluid temperature, and probably some other inputs) to decide when to deactivate Solenoid "A".
I'll look for your results and report mine when available. But in the meantime we might start searching parts stores and junkyards for replacement TCU's............
Post Title: Re: UPDATE: 94 240 conv with AT shift problems (ncaa1969) Posted by:240ROCKER at 5:32 PM 3/12/2005
Hey there ncaa1969, I finally got my LED hooked up this afternoon to the TCU pin 6. Did you have a lot of trouble trying to get at your TCU. The bottom screw was real easy to get, but the top one was behind the Blower Motor Housing. I had a heck of a time trying to get that thing out. I was finally able to loosen up the heater coil housing enough to wedge the Blower Motor Housing out of the way. I haven't has a chance yet to drive it around yet, I'm gonna do that in a few minutes. I'll report back here when I get some data. The fluid temperature sensor is an interesting theory too. I would think that that is a huge delta from 600 ohms to 2.5K. Maybe that could be our problem. I put in some of that tranny additive that is supposed to bring the fluid down about 10° and when I did that, I didn't have any problems for nearly two weeks. Interesting....
240ROCKER
Post Title: Re: UPDATE: 94 240 conv with AT shift problems (240ROCKER) Posted by:240ROCKER at 6:14 PM 3/12/2005
Well...I just returned from driving my car for a few miles and guess what happened? My car started doing the intermittent shift from first to second and the LED remained on, which means the tranny didn't get the signal to shift to second gear. I am going to drive it some more tomorrow and see if I can duplicate these results. It looks liike it might be the TCU.
I have read here and on other forums that they changed the TCU out and still had the same problem. I'm wondering if people got confused, and changed out the ECU, thinking that they were changing out the TCU. I know I made that mistake at first when I started looking for pin 6 and realized that the color of wire was not what the service manual indicated. The ECU is the very first box that you see when you remove the passenger side kick panel. The TCU is further up into the firewall behind the blower motor. It ain't no picnic to get out either!!!!! lol
I'll post back again tomorrow after driving it a while.
240ROCKER
Post Title: Re: UPDATE: 94 240 conv with AT shift problems (240ROCKER) Posted by:ncaa1969 at 5:26 AM 3/13/2005
240Rocker, I didn't make the connections at the TCU so I haven't fought with removal yet. I connected all at the terminal connector under the hood (bottom of three connectors by the fuse box).
I took resistance readings on the fluid temperature sensor at hourly intervals as the fluid cooled down. Resistance seemed to climb smoothly back up to 2.5K ohm range. So I'm doubting my hopeful theory of a bad fluid temp sensor.
But.......if the problem develops when the resistance drops to a certain level you could splice in a resistor and keep the signal from ever dropping into that range. Not sure what that would do to shifting patterns however. I'll mull this over some more.........
Of course there is one very easy fix that won't cure the problem but would make it easy to overcome. You could put an interupt switch on the power supply to the TCU. At every hangup just flip the switch on and off and reset the computer. Same cure as turning the engine off and back on but quicker and easier on the starter.
The saga continues.
Post Title: Re: UPDATE: 94 240 conv with AT shift problems (ncaa1969) Posted by:240ROCKER at 4:32 PM 3/24/2005
Well...here is an update for everyone on my quest to solve this intermittent transmission problem. First off, it is not the TCU. I was able to buy one that was rebuilt and guaranteed to work and if it didn't I would only be charged a $25 restocking fee. It was a gamble, but I went for it anyway. After I received it, I put in and after afew short minutes the problem reared it's ugly head. Sent it back and got my money back. Next, I took the car to my trusted transmission shop and he told me from the beginning that he really thought that it was electrical and not mechanical. After doing the LED test that I did, this just proved that the transmission isn't getting the command to shift to second. By me putting in a remanufactured TCU that pretty much rules out a bad TCU.
The transmission shop had it for three days tring to get it to act up and of course it didn't. In fact, he said that this tranny is in very good shape to have 149K miles on it. He said that the tranny is shifting great in all gears and that he couldn't detect any malfunction whatsoever and he has been in the business for thirty some odd years and he knows when a tranny is not behaving properly.
He suggested for me to put an LED on the other solenoid as well and see what state it is in when the shift problem occurs. I noticed that ncaa1969 has already done that and he reported that both LED's were on at the same time which means the tranny doesn't know what to do so it stays in 'limp' mode. This is where the tranny will still run but only in first gear. My tranny specialist said that if both LED's were on, than there is some bleed over from one solenoid to another which is caused by one of three things.
First, if when the problem occurs glance at the speedometer and see if there is some erratic movement back and forth of the speedometer needle. If there is erratic back and forth movement then the Speed Sensor is faulty. It is mounted on the side of the tranny. Second, if the speedometer is OK, then there is a wire somewhere in the main harness that has some of its insulation rubbed off and is somehow shorting to ground or a wire that goes to ground is loose. The third thing he said to check is all the interconnects between the TCU, ECU and tranny. It's very possible since these interconnects are right near the battery that there is some corrosion that has gotten inside one of these connectors causing intermittent connection. He suggested pulling them all off one at a time and give them a real good cleaning with contact cleaner.
My tranny specialist told me that he is nearly 100% sure that the tranny itself is just fine and for me to start looking electrically.
I told everyone from the beginning that I was going to find out what was causing this and I'm just about there.
This guy spent nearly four hours with me on this problem the last few days and I asked him how much I owed him for his time and he told me to "put my money away", that he was very happy to help me out as he wants to know what is causing the problem too so that he can file it in his database.
240ROCKER
Post Title: Re: UPDATE: 94 240 conv with AT shift problems (240ROCKER) Posted by:ncaa1969 at 3:25 PM 3/25/2005
240rocker, Thanks for the update and news that changing the TCU did no good. BTW, having both solenoids on is proper for first gear per the service manual, not a limp mode. A & B on equals first gear, B only equals second, none on equals third and A only equals fourth/overdrive.
I've been monitoring the voltage output of the fluid temperature sensor as the car warms up. The voltage drops normally from 1.6 volts to .48 volts and the hang up in first gear happens when the voltage is in the .75 to .8 volt range. Still no idea what that means, except that the hang up occurs at that voltage signal and accompanying fluid temperature.
I'll try the contact cleaner on all connections. Can't hurt. Might help.
I have no flicker of the speedometer, perhaps ruling out the speed sensor.
Post Title: Posted by:maik21 at 8:09 PM 3/26/2005
i have the same problem with my automatic transmision (s13) .... my car dont up shift.... i put into the "d" and it run fine, but dont upshift to "2nd" ; and i have to run in 1st near to redline and depress gas and it shift to 3th, but 2nd never work.... i did a tcu diagnostic and the overdrive light told me that the trans is fine. the solenoids a and b are in 24 ohms .... i disconect the trans arnes from the motor bay and put a 0 volts into solenoid a and 10volts into solenoid b, and no changes... i think that something is stuck!!! what i do to resolve this problem?? transmedic ??
Post Title: Posted by:NISTECH at 8:23 PM 3/28/2005 maik21 you got something different going on. The rest of you check your ground on the solonoid harness, It may be inside the pan with the solonoid pack. make sure the crimp on the wires is secure and the wires dont move back and forth in the crimp on the lug. If it does ,unbolt it and clean it thouroughly with brake clean ,dry it thouroughly , solider it to the crimp,make sure your solider flows properly into the wire. Rebolt it on reassemble the car and recheck it.
The led on the light only indicates voltage is present on that wire it does not indicate the tcm is not sending a signal. What it means is the load is not being used anywhere else in the circuit. Which could be a poor connection to ground at the solonoids. I am going to take a look at the service manual and see if I can be more specific on the grounds location.
Post Title: Posted by:NISTECH at 8:41 PM 3/28/2005
comforimed they are on the solonoid packs in the trans, check both of them , but your solonoid a and b use the same ground and are in a cluster of 3 solonoids all 3 solonoids share the same ground lug.
Post Title: Re: (NISTECH) Posted by:240ROCKER at 12:21 PM 3/29/2005 NISTECH, Thanks so much for your help on this. Could you please help me to understand by what you meant by the following: "The LED on the light only indicates voltage is present on that wire it does not indicate the tcm is not sending a signal. What it means is the load is not being used anywhere else in the circuit."
Electronics is my background and I don't understand what you are trying to tell me here. Is the tranny looking for a constant voltage to shift or is it looking for some sort of pulse??
Here is my understanding of what the LED I installed on pin 6 of the TCM is telling me. During normal operation, when the tranny is in first gear, the LED is 'ON' and right before it shifts to second the LED turns 'OFF' which tells the 1st to 2nd shift solenoid to shift...right? When my tranny doesn't want to shift to second the LED remains 'ON' which means the 1st to 2nd shift solenoid didn't get the command to shift. Is this a correct assumption on my part?
Now you also said that the load is not being used anywhere else in the circuit. This is the thing I'm having a problem trying to understand what you are saying. Are you saying that if the connection from the solenoid to ground has an intermiitent connection to ground, then it is not completeing the circuit and therefore there is no load because the solenoid circuit to ground is open?
Have you seen this problem before with the intermittent shift on and 240's you have serviced????
This just might be the big break we all have been looking for. I will be dropping the pan in a few days to check my ground out and to solder it.
Thanks again!!!!!!!! 240ROCKER
Post Title: Posted by:NISTECH at 6:44 PM 3/29/2005
I Have pondered this problem on and off throughout the day. I too have an electronics background before I got into this buisness. I keep analizing the senarios I keep coming to a dead end since the TCM supplies the power to the solonoid rather then Grounding it which is what control units typically do on nissans. I have not seen this problem on the 240s but have replaced solonoid packs for shift related problems on 240s. I brought that potential problem to the table for 2 reasons one is grounds tend to be a fairly common problem with nissans but also based what I told you on the operation of the typical control unit operation with other components on the engine. Hold off on doing this ground repiar/check till I can review the circuit in depth a bit more. I also brought this to the table since a recent bulliten came out on the altima for a ground issue similar to what I mentioned about the ground as it is throwing a solonoid code and causeing a shift problem from 1 to 2.
Post Title: Re: (NISTECH) Posted by:240ROCKER at 6:30 AM 3/30/2005 It's hard for me to suspect the solenoid being bad because it isn't throwing any error codes back at all. That is why I tend to agree with you NISTECH that I have a ground problem. I just wish I could be sure that is what it is before I have to take the time to drop the pan and valve body to get at the solenoid and the ground terminal. It also makes perfect sense that it's possible that the one wire from the shift solenoid 'A' is not crimped very well in the terminal or the ground terminal is loose. However, if the terminal was loose, I would think I would be having problems with other shifts as well and not just the 1st to 2nd shift.
So can you think of anyway I can verify that this is a grounding issue without going through the labor of dropping the pan and valve body as mentioned previously? Is there something else I can monitor on the TCM perhaps????
Thanks again! 240ROCKER
Post Title: Posted by:NISTECH at 6:43 AM 3/30/2005
I just got out of the service manual and stumbled across somthing I wasnt thinking of could be the problem. For the hell of it reach down by your gas pedal and unplug the kick down switch for a few days and see if your problem is gone. Its an easy test and the connector is easily accessable. I am wondering if it is sending a signal to kick it down when it shouldn't. I will continue to research but stay away from the panthing for the time being cause logically [after deep thought of its operation] it dosent make since that ground is the problem since the TCM supplies the power not the ground.
Have any of you takin it to the dealer and had them pull it up on consult and check for codes in the TCM? its not the same as checking codes in the ECM.
Post Title: Re: (NISTECH) Posted by:240ROCKER at 7:16 AM 3/30/2005
Yeah...When this problem first started happening a couple of years ago, I immediately took it to a dealer. Of course it wouldn't act up for them and they couldn't find anything wrong, so they suggested a tranny flush. I have since taken it to another foreign car specialist and they couldn't find anything wrong either.
I will remove the kick-down switch and try that. Regarding your comment about the solenoid being controlled by the power signal from the TCM. If the solenoids ground was not a good connection, as you previously stated, then the solenoid will not shift because the circuit to ground isn't completed and therefore you would have an open circuit. Meaning that the tranny wouldn't even see the solenoid. Right???
This is why I still think that the ground issue could be the culprit!!!! What are your thoughts on this?
240ROCKER
Modified by 240ROCKER at 9:39 AM 3/30/2005
Modified by 240ROCKER at 9:43 AM 3/30/2005
Post Title: Posted by:NISTECH at 5:30 PM 3/30/2005
the solonoid is always applied when its in 1st gear, when it shifts to second it turns the solonoid off(takes away the supplied voltage. For some reason its not taking away that voltage. I did find a good page in the service manual which lists all the inputs and outputs for the tcm. I need to go through it and see what is the potential problems and what wont effect the shift decision of the TCM. I have not done it yet and might later tonoght as I have to do some karate with my kids tonight. Both of them are goin up in belts tonight.pretty soon they gonna be able to kick my butt...lol
Post Title: Re: (NISTECH) Posted by:ncaa1969 at 6:26 PM 3/30/2005 NISTECH, Thanks for joining in our quest for a solution to this apparently common problem. We need the help! I disconnected the kick-down switch but it had no affect. The transmission hung up in first gear same as always.
I had suspected the AT fluid temerature sensor, but I monitored it and there was smooth steady change in voltage as the transmission warmed up - matched the service manual range from hot to cold. If it is of any value, the gear hangup always occurred when the voltage across the sensor was about .77 to .8 volts. Just to be sure, I cut the temperature sensor feed to the TCU and substituted a 2.5K ohm resistor so the TCU would think the transmission was still cold. No help - still hungup in first. Did the same with a low resistor to simulate fully warmed up - no help - still hungup at the same 5-7 minutes after a cold start.
Today I hooked my multimeter across the Throttle Position Sensor as soon as the hangup in first gear started. I got some off the wall readings, twice to three times normal. I should have seen about .5 volts at closed throttle but was getting about 1.3V with wide fluctuation. And the meter jumped to over 6 V at 1/4 throttle. It very well could have been due to one or both of my probes being loose. But within minutes I was getting proper readings (.44 V at closed throttle, about 1.0 V at 1/4 throttle) (it is a new TPS that bench-checked fine before installation)
I'll run the TPS test again tomorrow - I have to wait for full cool down.
Thanks again for your help on this. Greg (ncaa1969)
Post Title: Posted by:NISTECH at 8:41 PM 3/30/2005
run a wire from the tps tp the inside of the car and watch the voltage changes while your driving and see if it goes hay wire while driving.
Kick down is a negetive then.
Post Title: Re: (NISTECH) Posted by:NISTECH at 6:14 AM 3/31/2005
Ok here is a diagram of all the electrical components the TCM uses to control the trans.
There is a test i would like someone to conduct. If you have a multimeter that has AC capabilities I would like you to back probe pin 25 of the TCM. Measure between that terminal and ground. Watch it as you drive the vehicle see if the signal goes haywire or to 0v when it wont shift. This is the revolution sensor for the trans. it is not the revolution sensor for the ECM. This is an AC volts generating sensor. it should climb from 0v it a stop to over one volt at about 19mph and should steadily increase as you drive. You guys are going to have to start testing things till you find the one that is sending an eronious signal. The TPs is still a concern if it in fact is glitching still do the test on that as well.
Post Title: Re: (NISTECH) Posted by:240ROCKER at 6:28 AM 3/31/2005
Hey NISTECH congrats on your kids karate belt upgrade.
Here is a quick list of things that I have done in the order that I have done them to try to fix what is going on with my tranny, but to no avail.
1. Replace ATF and change filter 2. Transmission Flush by the Nissan Dealer 3 TPS replacement 4. TCM replacement 5. Remove kick-down switch
Here is something that someone did to fix their tranny problem and still had the problem!!!! 1. Transmission rebuild which included a soleniod pack replacement but did not include a rebuild of the valve body. After the rebuild was completed, it took about a month before the problem started happening again, but it did return.
240ROCKER
Modified by 240ROCKER at 10:45 AM 3/31/2005
Post Title: Posted by:NISTECH at 6:41 AM 3/31/2005
This is an electrical problem no doubt about it. But tests need to be done on components that effect the TCM's decision to turn off the A solonoid. Either its not seeing the load of the signal when it got it on or its not seeing the appropriate time to shift to 2nd[Throttle input,vehicle speed]
Post Title: Re: (NISTECH) Posted by:240ROCKER at 2:23 PM 3/31/2005 Well...I got bored today, so I went to my friendly neighborhood tranny specialist again and I had him drop the pan and we looked at the solenoid pack and the ground terminal for it. Guess what??? The ground terminal harness was already soldered and there wasn't any evidence of a cold solder joint or an intermittent connection. He also had a set of used but good solenoids that we put on as well. After leaving his shop, I drove about five miles down the road and I started having the intermittent shift problem! Ugh!!!!!! At least now we can rule out the solenoids and the ground circuit for them.
NISTECH, I saw your latest reply after I did this, (that's what I get for getting antsy and jumping the gun ) so now I'm going to put a DMM on the revolution sensor on the TCM, as suggested, and see what voltage I get when it starts acting up. Has anyone else had a chance to do this yet??? What else can I possibly monitor NISTECH???? We are running out of things to check!!!!!
240ROCKER
Post Title: Re: (240ROCKER) Posted by:ncaa1969 at 4:47 PM 3/31/2005
240ROCKER, NISTECH,
I ran the test on my TPS and got normal readings, not the fluctuating ones I saw briefly yesterday - must have been a loose back probe. My cheap DMM doesn't cover AC so I can't run the revolution sensor test. ncaa1969
Post Title: Re: (240ROCKER) Posted by:ncaa1969 at 7:53 PM 3/31/2005
Found a Multi-meter with AC voltage capability. hooked it up to the Revolution Sensor feed and went for a run. I got no reading throughout the drive on lowest scale of 200V which reads to the tenth of a volt. Triple checked the probes. I did switch to DC volts and read about .24 volts with no change with change in speed.
My manual says to check resistance across the revolution sensor. Manual says normal range is 500 - 650 ohms. Mine reads 860 ohms.
I'll be interested in 240ROCKER's results.
Changing the sensor looks like a chore. Need to support the transmission, drop the rear cross member and lower the transmission "as far as possible" to get access. Greg (ncaa1969)
Post Title: Posted by:NISTECH at 6:10 AM 4/1/2005
By the way greg I am working out of a 93/94 service manual as its the oldest i have. test procedures may be listed differently in both manuals. go to the self diagnostics section for a trans code for the rev sensor ,that is the test I was having you run. The problem with some of these sensors is the computer only looks for 0v or constant max voltage nothing in between when it decides to set a code. since you "A" resitance it means the TCM sees something and wont throw a code.
Post Title: Posted by:NISTECH at 6:12 AM 4/1/2005 Also note the terminal orientation on the 2 yrs might be different so take that into account when doing this. you may have to reffrence your manuals for the correct terminal arrangemnet.
Post Title: Re: (NISTECH) Posted by:ncaa1969 at 10:23 AM 4/1/2005 NISTECH, I have a 92 manual and terminal pins are the same. For whatever reason, my self diagnostic test does not work to give me the flickers on the OD on/off light, so I can't read codes to see if it indicates a problem with the revolution sensor. I have not pulled the panel to back probe on the TCU harness, I have been probing under the hood at the connectors by the fuse box. Can I get codes directly off the TCU? If so, how? I'm encouraged by looking at the revolution sensor as the probable culprit here because: 1. the resistance reading on mine is out of range. 2. no voltage present on terminal 25 during driving. 3. My manual include a "Symptoms Table" and the revolution sensor is listed as the third most probable source for not shfting fom 1 to 2, and is listed as the second most probable for "too high a gear change point from 1 to 2" 4. It is logical that the TCU would not shift up to second from first if it wasn't "sensing" increasing revolutions as the car accelerated. But I'm reluctant to plunk down the $150 quoted by my local Nissan dealer for a new revolution sensor, without someone else duplicating my findings. Perhaps 240ROCKER will get some similar failure readings on the revolution sensor. In the meantime, I'll call my Nissan parts department and see if they used to same revolution sensor on other Nissan transmissions (to broaden my chances of picking up a low mileage one at a junk yard.) Thanks again for your help and suggestions. Please send me more tasking and I'll try any tests within my ability. Greg
Post Title: Re: (ncaa1969) Posted by:240ROCKER at 12:29 PM 4/1/2005 Hey guys, I haven't been able to backprobe pin '25' of the TCM yet. I'll be doing that this weekend. However, I did manage to read the resistance rating from pin '1' to pin '2' on the revolutions sensor and I'm getting a reading of 831 ohms. Like your reading Greg, mine is out of tolerance too. I too called my Nissan dealer and he quoted me $143.61 plus 11.49 tax. Geeeesh!!! This thing is expensive. It doesn't look like to bad of a job to replace, but I want to be sure that this out of range resistance reading is indeed stating that this sensor is bad.
I was hoping that my Nissan dealer had one in stock so I could test its resistance but he didn't because this is a part they don't usually stock because he had never had to have one replaced before.
Looking around on this forum and others, I found several threads on some of the Infiniti cars that had this intermittent problem from 1st to 2nd and the fix seemed to be replacing the revolutions sensor.
Does anyone know where we can get discounted Nissan OEM new parts on the web? I have bought some before from some internet dealers, but I can't remember where!
I will do the O/D diagnostics test and I will also do the backprobe on pin '25' of the TCM and let everyone know what I find.
I really think that we are onto something now guys. Could this be the answer we have been looking for......????????????
240ROCKER
Post Title: Re: (ncaa1969) Posted by:NISTECH at 5:56 PM 4/1/2005
As far as diag mode without consult the only way to do it is the way your doing it. For the sensor go to a wreakin yard and test it with you DVOM if the ohms are with in spec it should be a good sensor regardless of the milage of the car. Here is the diagnosis procedure for the rev sensor per the 93 service manual, it should be on or around the same page in your manual. And remember if the TCM sees any signal from the sensor other then 0v or max volts weather its logical or not it wont throw a code. Meaning even if you were able to check for codes it may not throw one if the sensor is bad.
Post Title: Re: (240ROCKER) Posted by:240ROCKER at 8:31 AM 4/2/2005 I have emailed everyone in this thread who has experienced this problem, but not posted here, with the intermittent shift asking them to check their resistance across pins '1' and '2' of the revolutions sensor. I want to gather as much data as I can to prove this theory.
Now, I would also like anyone who has a good working tranny without the problem to check their resistance as well, so I can prove to myself that a good revolutions sensor does indeed fall in the 500-650 ohm range!
Thanks so much!!!!!! 240ROCKER
Post Title: Re: (NISTECH) Posted by:240ROCKER at 6:32 AM 4/4/2005
Hey NISTECH, I have personally contacted some of the people on this forum who are having this shift problem. Everyone who has checked their resistance from pin '1' to pin '2' has had a reading of 720 on up. Mine has 831 and others have had as high as 860. Do you think that since this is out of tolerance from the service manual's 500-650 ohms that this would mean our revolution sensors are bad???? THe person who had 720 said that his didn't happen everyday, but that it did happen. It seems that since the weather has gotten warmer here, mine is happening alot more often too.
240ROCKER
Post Title: Re: (240ROCKER) Posted by:NISTECH at 6:45 AM 4/4/2005
what needs to be done is one of 2 things, go to a wrecking yard with your ohm meter in hand and check some till you find one that is within tolorance. buy that one and test it in your own car. if it works you found your problem.
Option 2 find someone who does not have this problem AT ALL and have them test theirs to see if their sensor is with in or much closer to spec.
Post Title: Posted by:NISTECH at 7:09 PM 4/5/2005
Update!! got a little info and a real test for you to perform to nip this problem in the butt.
The revolution sensor is the governor of your transmission, a govenor is what decides to shift the gears. The common complaint from customers when this fails is "NO UPSHIFT FROM FIRST INTERMITTENLY" Sound familier? This sensor is the primary sensor that is used to decide to shift the trans. But guess what? It has a back up. That back up is the speed sensor in your dash which gets its signal form the speed pick up in the trans. When it goes to the secondary sensor it has seen a complete failure of the other sensor. Your sensor generates a voltage and it slowly increases as you speed up. if you had additional resistance in the circuit the voltage to the TCM would be lower hence a no shift or much later shift. Your resistance reading indicates you have a higher then spec resistance. What this means is your sensor is your problem. Since the sensor hasnt completely failed the TCM is not going to the back up.
Here is the good stuff. Here is where we are going to make it go to the back up. Flat out disconnect the rev sensor and drive it over enough period of time to determine that the problem no longer exists. Keep in mind your speedometer has to be working since it is the back up. If you do this and the car drives without incedent replace the sensor and plug it back in. Note you will get a flashing O/D light while its unplugged when you first turn the key on. just ignore it for now. It will drive fine without it plugged in.
Post Title: Re: (NISTECH) Posted by:swadude at 6:12 AM 4/6/2005
I've been following this thread for several weeks hoping one of you tech savy guys would find an answer, sounds like this might be it. I'm not a tech guy and I don't have a manual, can one of you tell me where to find the Revolutions Sensor and how to disconnect it? Thanks.
Post Title: Re: (swadude) Posted by:NISTECH at 6:29 AM 4/6/2005 Here it is. The connector should be gray in color.
Post Title: Re: (NISTECH) Posted by:ncaa1969 at 11:48 AM 4/7/2005 NISTECH, After two days driving and several opportunities for failure, the tranmission is operating just fine with the revolution sensor disconnected.
Congrats and thanks for getting to the bottom of this.
now I'll bite the bullet and buy a new revolution sensor (and report here if everything works properly).
Thanks again, Greg
Post Title: Re: (ncaa1969) Posted by:240ROCKER at 7:04 PM 4/7/2005
Well...here is what I have found! Since I disconnected the revolutions sensor to test the resistance across pins '1' and '2', I have not had the problem. This means all I did was reseat the connector and everything is fine. I'm going on six days without any problem. So...those of you with this problem might wanna try and clean your connector with contact cleaner or brake fluid, before replacing the revolutions sensor and be sure to put some non-corrosion grease on it before re-connecting it!
A BIG THANK YOU goes out to NISTECH and everyone else who contributed to the findings!!! I knew we could do it!!!!!!!!!
240ROCKER
Post Title: Re: (240ROCKER) Posted by:swadude at 7:04 AM 4/8/2005
Same thing here. I disconnected cleaned and reconnected every connector under the hood that I could get apart, (at the time I didn't know which one was the rev sensor). That was about 8 days ago and I have not had shift problem yet.
If the problem comes back can I disconnect the rev sens and just let it work on the back up mode without hurting the car, or should I get a new rev sensor?
The information from the guys on this board has saved me lots of time and $$$$, Thanks.
Post Title: Posted by:CDE at 6:51 PM 4/15/2005
This thread rocks.
I have been having some tranny problems (89 s13 auto), and they have been giving me a lot of grey hair. My 1st - 2nd is a rough shift 90% of the time and also in the top gear, it starts to shake/shudder/hesitate after going over 80 kph. I'm going to go clean that thing right now, and then as my test I will drive to my local electrical store and pick myself up a nice voltmeter. It really sucks because I haven't been able to drive on the high way (do to my problem about 80kph) so it takes a lot more time getting to work and stuff.
I'll let you guys know if it also fixes that problem....
But really I would like to switch over to a 5 sp. I really miss my stick shift (Just got rid of my corolla GT-s 5spd)....but it would sure be nice to at least have a working auto! The same thing has happened to me know...I have taken it to a mechanic (didn't act up for him) and then a transmission specialist (didn't act up there either) and a dealer (*suprise* didn't act up there either). I swear my Nissan is messing with my head sometimes.
Post Title: Re: (CDE) Posted by:CDE at 7:46 PM 4/15/2005
OK, my car seems to be a little different than that diagram...Just wondering what one is the rev sensor/plug. MSN is fussy and won't let me link my photo's so it's the last photo on this link:
Also, there's another picture on there that I was wondering about. It's the fourth pic in that link. Just wondering if there's supposed to be a ground coming off that plug near my dist. cap or something...
The 1, 2, 3 are all plugs that are under one another. just wondering if it's one of those or the circled one.
the mysterious connector that nothing is connected to...
Turns out that I can link them from my MSN website. yay.
Thanks, Chris
Modified by CDE at 8:00 PM 4/15/2005
Modified by CDE at 8:03 PM 4/15/2005
Post Title: Posted by:CDE at 11:33 PM 4/15/2005
I'm working on getting a better FSM so I don't have to ask these silly questions :P
Post Title: Posted by:NISTECH at 4:50 AM 4/16/2005 pic one, it looks like its 2 pic two ,nothing goes there
Post Title: Re: (NISTECH) Posted by:CDE at 10:40 PM 4/16/2005 Well, I unplugged #2 and has some weird results...it was stuck in 3rd even at fast speeds, and would upshift to OD when I tried to accelerate. I also just unplugged the #1 plug and that didnt change anything. It seems to do it less vigorously so I'm going to spray them real good with cleaner...and I'm still working on getting a feeler gauge to test the TPS (other thread in nissan online mechanic) or even a volt meter.
Post Title: Re: (NISTECH) Posted by:oldbald_sarge at 6:13 AM 4/17/2005 Thanks to all the techs that worked on this problem. All I did so far was unplug the sensor, and it has run just fine. I'm really surprised that it was not enough of an issue all this time for someone to call on the techs for help. Thanks again to everyone.
Post Title: Re: (CDE) Posted by:NISTECH at 7:13 AM 4/17/2005
Quote, originally posted by CDE »
Well, I unplugged #2 and has some weird results...it was stuck in 3rd even at fast speeds, and would upshift to OD when I tried to accelerate. I also just unplugged the #1 plug and that didnt change anything. It seems to do it less vigorously so I'm going to spray them real good with cleaner...and I'm still working on getting a feeler gauge to test the TPS (other thread in nissan online mechanic) or even a volt meter.
does your speedometer work? If it doesnt you will put the car in failsafe [3rd gear] as it wont have a back up sensor to goto for speed input.
Post Title: Posted by:NISTECH at 7:15 AM 4/17/2005
if you want to find the connector for it,go under your car and loacte the small black sensor near the tail housing[not the bottom one thats for your speedomter] It should be near the top. follow the harness back to its connector.
Post Title: Re: (NISTECH) Posted by:CDE at 11:18 AM 4/17/2005 Yes, I just picked up a brand new electronic speedo head about 2 weeks ago.
The new speedo didn't change much like I was hoping it would.
I found how to do a self diagnostic using the OD light, but my light isn't working...(the od light next to the hazard lights). It doesn't come on when I take OD off. The cruise light also doesn't work (but the cruise does now with the new speedo head).
Post Title: Re: (oldbald_sarge) Posted by:MrUnderhill at 4:59 PM 4/20/2005
Well, if anyone remains unconvinced that the revolutions sensor (or some aspect of it) is the cause of our problems, let me weigh in with my experience. I unplugged the connector yesterday and have been driving for 2 days now with no shift problems whatsoever. Just curious - for those of you who cleaned the connector and then reconnected it, how did you do it? I was not sure about the posts talking about contact cleaner, brake fluid and non-corrosive grease - did you clean the exterior only, pour it in the connector, where does the grease go, etc.? I'd like to clean the connector and plug it back in to see if I have the shift problem again (bad sensor) or not (dirty connector).
A huge thank you to all of you who took the time and made the effort to get to the bottom of this. For those of us who are not tech-savvy, you have saved us a lot of money getting to the bottom of this. Thanks again.
Post Title: which plug Posted by:flint at 1:40 PM 4/21/2005
Mine is exactly like yours and I unplugged #1 and that`s the correct one. Only been 24 hours, but so far so good. Good luck, Flint.
Post Title: Re: which plug (flint) Posted by:CDE at 11:56 PM 4/21/2005 #1 on my pic? I tried that one but it did not fix it for me. I'm thinking it's the TPS now...I finally bought a volt meter so I can do a test on the ATCU soon as I can...
Post Title: Re: which plug (CDE) Posted by:TofuTechS13 at 4:41 PM 4/22/2005 i'm having a shifting problem also. No matter if i lightly tap on the gas or floor it, the only time it shifts is at certain speeds, 1st to 2nd at 25 mph, 2nd to 3rd at 46 mph, and 3rd to 4th at around 60 mph. I read this whole article but i'm unsure whether this is related to the intermittent shifting. Do i do the same things as listed in this thread or is it some other problem?
Post Title: Posted by:NISTECH at 4:51 PM 4/22/2005 I think your dealing with something other, but your shift points look ok.
Check your tps.
Post Title: Re: (NISTECH) Posted by:CDE at 12:33 AM 4/26/2005
Hey dude,
I just have a few questions. I ripped apart my passenger side kicker panel - removed the panel, the fan motor and the bottom half of the fan ducts so I could get at the ATCU. Now, I've taken pictures of what I've found thus far...
This is I think the ATCU, which was right above the bigger elec. control unit on the side wall right near the front. My manual wasn't the greatest but I'm pretty sure that's the atcu.
This is where it gets weird. I went to test the voltages across the TPS but...there was no power or ground wire for the tps, according to my manual.
These were the 2 plugs from the unit:
According to the manual, pin 3 and 5 are supposed to be the power to the TPS...but as you can see from the picture below, there are NO wires in those spots! It's supposed to be a 12 volt reading or whatever my battery is at, and then the tps is closed throttle .4-4 Open throttle...
I guess my main question is if I'm checking the right component and pins. Also, can I just unplug the connections and test without them plugged in, or do they have to be plugged in.
I'm going to give it another go tomorrow morning...It was so damn hot this afternoon I had to jump into the 60* pool to cool off....that really took my breath away It's finally been nice enough to get the pool up and runnin
Post Title: Posted by:NISTECH at 5:09 AM 4/26/2005
Whoa your an ambitious one!! just test it at the TPS itself, dont worry about testing it at the control unit just yet. I dont have a 240 service manual that old on hand so I can not verify what pins your looking at.
Post Title: Re: (NISTECH) Posted by:CDE at 12:55 PM 4/26/2005
Quote, originally posted by NISTECH »
Whoa your an ambitious one!! just test it at the TPS itself, dont worry about testing it at the control unit just yet. I dont have a 240 service manual that old on hand so I can not verify what pins your looking at.
Um...where exactly is it?
I think I have a good idea but I'm going to just start to prod and poke...
Another question....can I buy 1 screw at the dealership 'cause I lost one that held the fan unit in place. The damn thing didn't stick to my magnetic ratchet like it should have and fell into a void that has no return I will probrably just substitute a less important screw but I just don't want anything to rattle around.
Post Title: Posted by:NISTECH at 4:54 PM 4/26/2005
it is on the drivers side of the throttle body toward the engine block. kinda a bugger to get to but you shouldnt have to reposition much to gain access.
Yes you can buy just one screw at the dealer.
Post Title: Re: (NISTECH) Posted by:CDE at 6:28 PM 4/26/2005
Thanks
Is it easier to get to going from the top or bottom?
I don't have time today and am losing light so I'm just going to do it tomorrow morning.
Modified by CDE at 11:08 PM 4/26/2005
Post Title: Posted by:NISTECH at 7:26 PM 4/26/2005
from the top. over the intake tube.
Post Title: Revolution sensor Posted by:flint at 4:29 PM 4/27/2005 Great news, 10 months!!! now since I unplugged the Revolution sensor, still shifting perfectly! Thanks! Flint. secondly, do I need to worry about replacing it since there is a secondary one in dash?
Modified by flint at 2:04 PM 5/14/2005
Modified by flint at 11:04 AM 7/30/2005
Modified by flint at 10:39 AM 12/3/2005
Post Title: Posted by:CDE at 11:59 PM 4/27/2005
*sigh*
I wish mine was that easy :P I tried unplugging that one but it didn't do squat...I'm finally going to check the tps tomorrow...now that I know where it is :P
Post Title: Re: (CDE) Posted by:CDE at 6:47 PM 6/19/2005
I finally took it to a shop because I was getting no where. All my tests were showing the tps and rev sensor to be workin properly.
Turns out, it's nothing electronic and it's nothing external to the tranny like sensors and such. Mech figured it is just a weakening tranny. UGH. I'm praying that he's wrong and that it's the drive shaft some how. It shudders when it's under torque at low speeds - weak U joints. I've had it off a few times - once it helped the shudder, but the second time I took it off, it made it worse. I'm not sure if it's the culprit for the apparent tourque converter 'shudder' (not locking up properly - or so I thought). does anyone think it could be possible?
When it was at the mech shop he added some anti-friction atf. it helped the rough 1-2 shift a little but not the (apparent) TC shudder...
Post Title: Posted by:CDE at 11:42 AM 7/17/2005
Well, I finally figured out what was causing my shaking (when I first take off) - The problem was my steady bearing that is on the driveshaft. The mechanics I had taken it too put rather large dots on the driveshaft and bearing so it wasn't lined up perfect. Just being out an 1/8th or a 1/4er inch caused a rather annoying shake. I'm sure it has alos fixed or at the very least improved my shimmy that I was experiencing once I would hit 80+ km/h.
This is just for a reference if someone else is having a shaking problem when they are first taking off from a stop, and possibly the shimmy at higher speeds.
Just take a string and make sure the shaft is lined up properly measuring it from the center of the circles on the u-joints. Just loosen the 2 bolts (see pic) and twist the bearing until the shaft is aligned properly. The bearing isn't perfectly round so just twisting it will make a difference if the shaft is strait or not. Just putting dots on the pinions and bearing were not good enough to get it perfectly strait. Use a string
Specs: 1989 240SX coupe 24KAE (SOHC) Automatic
Hope this helps anyone else with this problem so they don't spend 5 months trying to figure out what the heck it was...
I apologize for the crappy picture, but my car is low, and my batteries died right when I took that pic so I couldn't get a better one... But that's the steady bearing.
Modified by CDE at 11:59 AM 7/17/2005
Post Title: Posted by:blues14 at 3:51 PM 7/17/2005
my 89 240 is doing kinda the same thing. except my biggest problem is the car decides to not start out in first gear once it is warmed up. also, the gear selector will not go into D1 position.
Post Title: Re: (NISTECH) Posted by:tumolt at 5:20 PM 7/24/2005 Thanks to you all for the information. I just inherited my 82 year old mother's vert with 79K miles. While driving it I recently had the tranny hang up in first gear. What the heck? After joining up with this site I fell into your quest to find answers. I am taking your advice and disconnecting the Revolution sensor and cleaning the contacts. I hope to report similar results. Thanks, Matt
Post Title: Re: (tumolt) Posted by:tumolt at 7:57 AM 9/18/2005 Well I ordered the revolution sensor, it should be in by Wednesday and my friend will install it for me. I disconnected the plug as shown and am able to drive the car but still I have intermittent problems with the shifting if I accellerate too quickly. When I drive slow it seems to work (more or less) I will know more after the new rev sensor is installed. I wonder if there is a key code to resetting the transmission since it is computer controlled. Anyone have thoughts on this before I get the part? Thanks, Matt
Post Title: Posted by:jackchoo at 2:21 AM 10/8/2005 anyone there who can help?? This is a S13 Auto transmission by the way...
update : I notice that it happens quite predictably :-
- from a cold start (after 2-3 minutes warm up) - after 6-7 minutes of driving - at that point I'm normally in heavy traffic so coasting real slow towards the freeway entrance - enter freeway, accelerate - and it cannot get out of first gear!!! - stop the car dangerously by the side - and its all ok for the rest of the journey! till the next cold start go back to the top.
It pulls out a code 43 when this happens (TPS) for the TCM and ECM. But I've already swapped with a good tps and have even checked it on a scope first.
One question though : is the TPS harness 0V reference supposed to be directly grounded to the battery. My multimeter seems to show a direct short to body/battery ground.
Post Title: Re: (jackchoo) Posted by:oldbald_sarge at 3:52 AM 10/8/2005
I hate to see you in such pain. Refer to nistech reply of 4/6/2005, 6:29a.m., pull the sensor, it works immediately. You will be amazed, as everyone else was.
Post Title: Re: (oldbald_sarge) Posted by:jackchoo at 7:28 AM 10/8/2005 ok i will try that. But still weird that the ECU pulls in code for the TPS...
Post Title: Re: (oldbald_sarge) Posted by:jackchoo at 6:45 AM 10/19/2005 tried this fix....no more gear stuck for the past 2 weeks. Thats a big improvement! So the next question is, why would I need to replace the revolution sensor? I suppose its there for a good reason......and anyone know what part number is it? I'm thinking of getting it changed..
Post Title: Posted by:NISTECH at 6:51 AM 10/19/2005 The car has reverted to the speed sensor for shifting as a back up. If the speed sensor glitches you will get stuck in third gear and there is no back up at that point. Taking off from a stop in third gear is no fun, especially in heavy traffic. The car is in a failsafe mode now but not as drastic as if you had nothing. This would be the reason to get the other opne replaced.
Post Title: Re: (NISTECH) Posted by:jackchoo at 7:11 AM 10/19/2005 anyone changed theirs yet? should I try cleaning the connectors first?
Appreciate if someone can show me exactly where its located....?
Post Title: Posted by:jackchoo at 11:40 PM 10/21/2005
ok so with the rev sensor disconnected I find that I get poorer fuel economy. Used to do 10 days on a tank now I only do 8days (for the past few weeks).
Anyone fixed the rev sensor or got it changed successfully? any advice appreciated before I go out there and buy one....
Post Title: Posted by:idrow at 12:16 PM 10/31/2005
This problem has been haunting me since '99. I have 2 240sx convert's (92 & 93) and both have this shifting issue. It's annoying as hell. Other than that, they run like tops (one has 234k and the other has 102k). I can't wait to try the revolutions sensor solution. I'll let you all know how it goes. Thanks to all who worked so hard at finding an answer to this! I pray this fixes it for me.
Post Title: Posted by:jackchoo at 7:11 PM 11/2/2005 update...was planning to change the sensor so the tranny shop dropped it to check on the part. They took it out, put it back and said they need to order the rev sensor and it costs about USD200 for the part. I told them I'll try to source for a cheaper one and they put everything back, FOC.
It has been 3 weeks now, with the rev sensor connected again, no re-occurrence. If you guys can access the sensor itself, perhaps its a good idea to give it a good clean + the connectors and harness nearby.
If it fails again, I'll do it once more!
Post Title: Posted by:kornaz at 4:29 PM 11/11/2005
Funny thing, but i had a 93 Conv a year ago and i had EXACT problem. But mine appeared whenever it wanted - not after exact time or being cold. Just wouldn't shift to second gear. It was embarasing going home 7 blocks in first gear lol. Sold it a bit later
Post Title: Posted by:NISTECH at 7:45 PM 11/11/2005 In the event of occurance , throw it in neutral and let the rpms come to idle for a few seconds, throw it back in drive and it SHOULD start shifting again. Works on mine every time. YES I know what your thinking, "your car does it, you know how to fix it, your a tech and can do it pretty easily with a hoist, yet you just let your car do it?" The answer is YES. I know it wont hurt anything if I work around it when it occurs and just let it go, besides I am throwing a manual trans in it, which by the way I have all the parts to do it, I just cant get myself motivated to actually put it in. Its not a paying job....lol
Post Title: Re: (NISTECH) Posted by:onosqv at 3:03 PM 11/15/2005 Anyone have a better picture of the rev sensor location? ... & # of wires on that connector? I see several gray connectors by the fuse box .
Post Title: Re: (NISTECH) Posted by:240SX@MD at 8:37 PM 11/17/2005 Hi,
First of congrats and thanks for the great help to all involved in this issue!!, i just finished reading it and as you'll read below my transmission showed it's first symptom a few hours ago...
I have my '93 240SX for about 7-8 months now. The first problem i encounterd was the roof leaks. So i finally replaced my convetible top this week. I pick it up today after work (it is so nice to be able to see through the back window again.) And on the way home turning right after a red light my transmission would hesitate shifting to 2nd and then would not shift at all.
Great I thought, i just fixed my top and now the tranny doesn't shift. Pulled over / turned on the hazard lights and let it idle on P, then I cycled through R N D 2 1, for a few secs on each gear, something similar as NISTECH described two posts ago. Then put it on drive and no problems at all on the way home.
For stats and history it was about 32F around 9pm here in the DC area. First thing as i got home, log in to NICO Excellent write up!!! I know now that it will happen again sooner or later, so I will I do the recommended check ups and keep posted for the outcome.
Question, how often do you change AT fluid (drop pan/change filter/clean magnets/put new gasket)? on my previous car I used to change it every 30K mi.
Many thanks, regards,
Luis.
Post Title: Re: (CDE) Posted by:240SX@MD at 8:53 PM 11/17/2005
CDE: I have the exact same vibration (shimmy) problem.
I have the shaking and shimmy at high speeds, yes, exactly at 50mph (or 80kph +) mine does the same, and it its very annoying. I have replaced all my tires and balanced/ and rebalanced... And I was about to put new bushings all-around as someone told me. But I'll try the driveshaft aligment first as you mentioned. Can you show a wider picture, maybe the whole drive shaft? and which bearing should i turn/twist? Thanks in advance. Has anyone experienced this shimmy at cruising speeds before?
Sorry, I know it is not on the right topic thread.
Thanks again,
Luis.
Post Title: Re: (240SX@MD) Posted by:nissanconvert at 2:01 AM 11/18/2005
I just bought a vert and mine shakes at around 60mph or so, I took it to get rebalenced and the guys at the shop said one of my rims is bent and probably causing the shakes. I got a new rim but haven't had it installed yet to see if it worked. It probably not your problem but just thought i'd throw it out there anyway.
Post Title: Posted by:Florida240sx at 7:36 PM 11/19/2005 If anyone can get a pic of the sensor.I'm confused on it's location.Got pulled over the other day for when it revved up and then shifted at abotu 7500rpms and tires broke loose as I was turning.
Post Title: Posted by:S13inBatnRuge at 9:00 AM 11/20/2005 i have a '93 coupe and mine was on the left side of the car ( standing in front of it, not sitting in it) in a group of wires near the right strut tower. it had a group of three gray connector and one brownish/red connector. look for the three pin connector. and remember when you start your car it will flash on your o/d light a couple of times.
Modified by niteboo at 7:43 PM 11/20/2005
Post Title: Posted by:S13inBatnRuge at 8:28 PM 11/23/2005 had the same problem. unplugged it last friday and hasnt missed a beat yet.
Post Title: Re: 94 240 conv with AT shift problems (oldbald_sarge) Posted by:240conv at 9:29 PM 1/23/2006 please pay attention your problem is the rpm sensor mine had that problem this site told me about this disconnet it, it is there on your left side when opening your hood,there are 2 or 3 that look alike when you disconnect it it shifts perfect.
Post Title: Posted by:donmeca2020 at 10:55 PM 1/25/2006 so is this only happening to people up north where it gets very cold or what? when we went to test drive the one we're about to pick up it was cold and had no problems with the tranny shifting. let know about this. because im in the more warmer climate and would like to know if i should worry also.
Post Title: Re: (jackchoo) Posted by:idrow at 5:39 AM 3/20/2006 Well, I finally disconnected the revolution sensor this weekend - no good. Once I did that, it wouldn't shift out of first. Sigh. It's amazing that this seems to be a universal problem with these cars and that there isn't a concrete diagnosis and solution. Sigh. Love the car, hate the trans
Post Title: Posted by:hatchback240 at 10:39 PM 3/23/2006 a couple of things of input: -to answer donmeca2020's question, no, its not a northern thing, i live in abilene, tx, and my 93 hatch started acting up on me not 2 days after i got it. - thank you to the major benefactors who made this discovery happen, my dad was about to put my 240 in the shop, im so glad i found this!! we have enough money to get by, but not enough to replace a tranny, or have it rebuilt. you guys deff made my night :D -im not 100% sure i disconnected the right sensor, under the hood, between the pillar and fuse box there are three sets of connections, one is red, its the bottom set, then there are two grey connections above that, i disconnected the middle. my car runs alot better, no sticking, but it does seem to shift different, it would upshift and downshift at particular speeds, say 3-4 at 40mph, and 4-O/D at 60mph (atleast i think thats how the gears work, but the speeds are correct).
any input would be greatly appreciated, again, thanks for everything!! life savers :D
Post Title: Re: (donmeca2020) Posted by:bankrup3000gt at 3:19 PM 6/8/2006
I live in Tucson,Az and it happens to mine once in a while. Hasn't tried any fixes. I don't drive it much. Wife's car and she doesn't notice it as much as I do.
Post Title: Re: 94 240 conv with AT shift problems (oldbald_sarge) Posted by:deblouthomas at 10:00 PM 6/14/2006 I had a black 93 that did that exact same thing at only about 70K. I solved the problem by trading it in on a red 95 the same day. Although I loved the new body style, I have always regretted giving up my black beauty ragtop Debbie
Post Title: Re: 94 240 conv with AT shift problems (deblouthomas) Posted by:kc240guy at 6:38 PM 6/29/2006 hey i know how to fix it and it costs nothing. you see theres a sensor that measures the resistance in the line and makes it shift according to that. cuz its an electronic tranny. theres a second way the car can shift. it just goes by the engine rpm and throttle position which is the better way to do it but it doesnt by default. all you gotta do is pull a sensor plug. its behind the battery a little bit and its the top one. pull it and the car will never do it again. the previous owner did the research and fixed it and told me about it . so far ive helped a couple other people with the info. you will also notice the od on light blinking right after you start it.
Modified by kc240guy at 6:54 PM 6/29/2006
Post Title: Re: 94 240 conv with AT shift problems (kc240guy) Posted by:sudcricket at 10:15 PM 8/7/2006 Hi, I have a hyundai Elantra 1997 model. and I have a gear shift problem. The problem doesnt happen when the car is cold, but as it runs and temp increases the car wont shift from 15-20-25 mph. as if its stuck and then moves hard. I read the topic on nissan 240 similar problems with many owners and the solution found was "removing the plug from revolution sensor, and the backup speedometer will tell the module when to shift". Is there any such solution for Hyundai Elanta aswell. Please do let me know, you can also e-mail me at simsudra1@yahoo.com.
Thanks, Sudhakar
Post Title: Posted by:tcrow31 at 4:25 PM 9/14/2006
To everyone that posted here, did replacing the Revolution Turbine Sensor fix the shifting problem? I am currently having the same problem. i have no 2nd and 4th gear here is a link to my post. http://forums.nicoclub.com/zerothread/197088
Post Title: Posted by:NISTECH at 5:54 PM 9/14/2006 I read through your post and know it doesnt sound like your rev sensor I think you have something internal going on inside the trans. perhaps wrong fluid or contaminated fluid.
Post Title: Re: (NISTECH) Posted by:tcrow31 at 7:07 PM 9/14/2006 It could very well be. I tried unpuging the turbine sensor and it didnt make a change. the only weird thing is that this happened all the sudden with no warning. that morning it shifted fine and i parked for like 2hrs then drove home and at first it was fine then i noticed no 2nd gear and 4th. now im wondering if a silonoid is cloged. i know this section is for the 240s but would you happen to know where to get to the silonoids and where i can download a FSM possibly for free for my car. Did a search and found one for everyone else except mine.
Post Title: Re: 94 240 conv with AT shift problems (240ROCKER) Posted by:jamesblonde82 at 12:24 PM 9/15/2006
Quote, originally posted by 240ROCKER »
Well guys I found out something interesting about having your automatic transmission rebuilt. Apparently, when you opt to have your automatic transmission rebuilt, this does not include rebuilding the "valve body" which is the brain of the transmission. Several people have posted on here and on other places on the internet who decided to rebuild their transmissions only to find out that they still had the shift problem. What a bummer to know that you spent all that money for a rebuild and it didn't actually fix the problem.
The valve body has all sorts of control valves and springs and is a very expensive part to replace, which is why most tranny shops don't rebuild or replace these.
I have learned that more than likely I have a stuck control valve in the valve body and the reason that I normally don't have a problem in colder weather (50° or lower) is because there is more pressure being built up in the valve body to compensate for the colder temps. and when it's warmer weather, the pressure isn't as high and therefore one of the control valves that pertains to the 1st to 2nd shift is getting stuck. I was told that an additive called "Transmedic" might unstick this valve. It will take about two to three weeks to really get into the system, but that it might keep that control valve from sticking.
What are your thoughts on this?
240ROCKER
Modified by 240ROCKER at 1:03 PM 3/1/2005
i can vouche for that. i rebuilt my A/T about 6 months ago. it was slippin, shifting slow. then finally the torque converter went out. so i did the whole nine yards. i seen the valve body, made sure it was operating by blowing pressure in it. it shows u how to check in the rebuilt kit manual. basically all i changed was the clutches and rings and what not and of course the torque convertor. so now it drives a LOT better, but it still shifts slow. like the valves are working but not fast enough. this must be a issue with these cars for sure. while doing this, i also found out you can use pathfinder transmissions. so if any of you guys ever just want to swap to a used one, you can use the pathfinder as well. but if you rebuild a pathfinder tranny, make sure you get the parts for the pathfinder, not the 240. the 240 clutches arent as thick. if u put them in a pathfinder tranny, you will have serious shifting probs. and dont ask me how to tell the difference if youre not sure. i found out when mine was completely apart that it has the pathfinder tranny in it by measuring certain internal parts and comparing them to a chart. then i wrote on the tranny for any future reasons, that its a pathfinder tranny. good to know these things.
Post Title: Re: 94 240 conv with AT shift problems (kc240guy) Posted by:jamesblonde82 at 12:46 PM 9/15/2006
Quote, originally posted by kc240guy »
hey i know how to fix it and it costs nothing. you see theres a sensor that measures the resistance in the line and makes it shift according to that. cuz its an electronic tranny. theres a second way the car can shift. it just goes by the engine rpm and throttle position which is the better way to do it but it doesnt by default. all you gotta do is pull a sensor plug. its behind the battery a little bit and its the top one. pull it and the car will never do it again. the previous owner did the research and fixed it and told me about it . so far ive helped a couple other people with the info. you will also notice the od on light blinking right after you start it.
Modified by kc240guy at 6:54 PM 6/29/2006
can you be a lot more specific. was it the fuse box? what relay or whatever was is that you pulled?
Post Title: Re: 94 240 conv with AT shift problems (jamesblonde82) Posted by:kc240guy at 10:45 PM 9/16/2006
the fuse box behind the battery. there is a set of plugs behind that box. pull the top one.
Post Title: Re: 94 240 conv with AT shift problems (kc240guy) Posted by:Glyph at 3:03 AM 9/17/2006 This write up is incredible. The amount of cumulative time and money that has been saved by the efforts and diligence of a couple of dedicated Niconauts is staggering. When I first bought mine I too had the exact same problem. Instead of dumping big bucks into it only to receive nothing back but frustration, I found this post, followed it to a tee, and haven't experienced even a hint of the problem in over three months now. THANK YOU guys. You know who you are.
Post Title: Posted by:acidbbg at 12:16 AM 10/11/2006 good work guys!
Charlie
Post Title: Posted by:Florida240sx at 3:04 PM 10/11/2006
Been going good now for 3 weeks Too ba dmy engine is toast, and now swapping in a vg30dett
Post Title: Re: (Florida240sx) Posted by:MNVERT at 12:15 AM 4/10/2007 my tranny wont shift into any gears when in drive,reverse,etc. anyone had this problem b4?
Post Title: Re: 94 240 conv with AT shift problems (oldbald_sarge) Posted by:tumolt at 5:54 PM 4/16/2007 I went through the same thing. You're wasting time and money trying to figure what is wrong with your transmission. I went through two repairs only to find out the reason for the intermittent shift was a burned out resistor in my computer. It is located on the passenger side wheel wall behind the plastic cover. It is a mother to get to and you'll see two boxes, one on the bottom and one way up top. The one up top is the computer. You'll have to pull the fan motor (a big feat) but can be done. I left one clip off since it was a mother to put back on. You have to take the cover off of the computer and check to see if there are any burned components. Some companies do sell rebuilt units. Mine came from ACE in Hollywood, Florida at a cost of $150. I wish I knew before going through two rebuilds. It might be a good time to think about that too! Other than that, don't overheat your motor or you'll be going through what I am with a valve job and a mechanic who can't get it to run. These cars are nice but the mechanical problems that come up are no picknic. Good luck. Matt
Post Title: Re: 94 240 conv with AT shift problems (tumolt) Posted by:MNVERT at 1:33 PM 4/17/2007
Quote, originally posted by tumolt »
I went through the same thing. You're wasting time and money trying to figure what is wrong with your transmission. I went through two repairs only to find out the reason for the intermittent shift was a burned out resistor in my computer. It is located on the passenger side wheel wall behind the plastic cover. It is a mother to get to and you'll see two boxes, one on the bottom and one way up top. The one up top is the computer. You'll have to pull the fan motor (a big feat) but can be done. I left one clip off since it was a mother to put back on. You have to take the cover off of the computer and check to see if there are any burned components. Some companies do sell rebuilt units. Mine came from ACE in Hollywood, Florida at a cost of $150. I wish I knew before going through two rebuilds. It might be a good time to think about that too! Other than that, don't overheat your motor or you'll be going through what I am with a valve job and a mechanic who can't get it to run. These cars are nice but the mechanical problems that come up are no picknic. Good luck. Matt
thanks for the info i think thats what it is , i just ordered parts for the manual 5speed swap but im gonna try that first to see if it is what u said cause i think it is a electrical problem ill keep u guys posted...
Post Title: Re: (NISTECH) Posted by:Pathfinder_1997 at 2:57 PM 5/3/2007 Hey I am new in this forum but this Nico Club is the best Nissan Source on the Net. I have a 1997 Pathfinder LE and I have a problem in the tranny. I start the engine and in about 15 minutes of driving the tranny upshift the overdrive and downshift the overdrive is just do this all the time this lasts months. I want to know if it the revolution sensor have something to do whit this? If have something to do where is it?
THANKS!!
Post Title: Re: (NISTECH) Posted by:nosferatu226 at 10:13 PM 7/16/2007
I just bought a 93 240 today and it has the same problems everyone else seems to be having but a little different. It will only shift from first to second at around 6000 rpm, and from second to third at redline. I've only had the car for a few hours now but i havent seen it do anything other than that. I tried removing the revolution sensor (the top plug behind the fuse box?) but it didnt shift at all and the car had much less power. The car also has some other electrical problems that make me think it could be a problem with the wiring harness? The tail lights and brake lights stay on when i turn the car off so I have to disconnect the battery when i turn the car off, the pop-up headlights sometimes stay up but if you press the button to make them go up and down enough times they will eventually go down, also the e-brake light inside the car stays on most of the time but will sometimes go off. I didnt know if any of that stuff might be connected in some way to the transmission screwing up. Maybe i just have a lot of sh*tty wiring? I hate automatics...guess you can't complain when you get a running car for $400 though. If anyone can help that would be nice. Great job on the rest of the thread by the way. Looks like you guys spent alot of time on this.
Modified by nosferatu226 at 10:13 AM 7/17/2007
Post Title: re: Posted by:aradapilot at 12:20 PM 7/18/2007 I've been having a problem like this recently...I had the car off the road for a while as my camshaft snapped (yes, snapped in two) and finding another was a pain, and now that I swapped the new one in and went for a drive she wouldnt shift until near redline. It seemed electrical...as the tranny had been fine up until then and a few connectors had to be taken apart to do the timing work, including the tps. When I'm home from work tonight I'll try undoing the rev sensor...hopefully it's that, maybe hurt from sitting not running for a while during a heat wave...you'll hear back from me soon.
And a note, I read this whole thread and it's been immensely helpful - would've taken me forever to test all that by myself. Thanks all! Hopefully this will get linked in a sticky or something as it seems to be a common problem.
Post Title: Posted by:aradapilot at 5:26 PM 7/18/2007
Okay...same problem with it unclipped (the top connector with 3 prongs next to the relay box, right?). So, trying to figure out what it is. More details: shifts 1-2 at redline. shifts 2-3 at about 5500-6000. haven't gotten to 4 yet, as i'd need to go about 80 to redline it in 3rd and I don't want to go far from home to a nice highway or anything until I work this out... also, when it finally does shift, if i let off the gas the rpms drop down to about 1k even if the engine should be held higher by the trans...not sure whats causing this. I can get back up to a normal range easily and the torque kicks right back in. note: having gears 1,2, and 3 means all solenoids fire. I tried disconnecting the kickdown switch too...no luck there. Could this be a problem with the tps? what other inputs are used? It seems like the rev sensor disconnect worked for everyone but me...though my problem sounds identical.
Post Title: Re: (aradapilot) Posted by:nosferatu226 at 2:11 AM 7/19/2007
Quote, originally posted by aradapilot »
Okay...same problem with it unclipped (the top connector with 3 prongs next to the relay box, right?). So, trying to figure out what it is. More details: shifts 1-2 at redline. shifts 2-3 at about 5500-6000. haven't gotten to 4 yet, as i'd need to go about 80 to redline it in 3rd.
yeah thats exactly what happens in mine.
Post Title: Re: (nosferatu226) Posted by:aradapilot at 11:07 AM 7/19/2007
could be tps or vss...it's going to be hell pulling my atcu out. any other ideas?
Post Title: Re: (aradapilot) Posted by:nosferatu226 at 6:07 PM 7/19/2007 I've got it in a shop right now. Hopefully they can figure something out. I'll post it if they do.
Post Title: Posted by:aradapilot at 12:05 PM 7/20/2007 It's the TPS. was throwing 2.68V at closed throttle as opposed to the 0.4 expected. Just got a replacement, gonna swap it in a little later, I'm tired as hell. Check the voltage on term 20 on the ECU (NOT atcu) to ground, see if it gives 0.4 at closed throttle and 4.0 at open and ranged in between. Sounds like you're having the same problem as me. And driving with the bad tps disconnected was fine. Obviously it shifted based on the charts in the fsm rather than pedal pressure, but otherwise performed beautifully.
Post Title: Re: (aradapilot) Posted by:nosferatu226 at 9:30 PM 7/20/2007 thanks for the info, let me know how it turns out
Post Title: Re: (NISTECH) Posted by:LushPenguin at 8:35 PM 7/22/2007 hey man, you're totally correct!!!!
After noticing "rockers" photo I dropped what I was doing, went out ,and unplugged the top plug behind the battery & fuse box..... That was 3 days ago and I've put almost 80 city miles on my car since then and it has run perfect!!!!! THIS IS A HUGE DISCOVERY!!!!
YOU ARE SAVING US BIG $$$$$ Give me a few weeks and if this still works I will mail you both a check for $75.00 each.... I wish I could do more but I'm at a transitional stage in my life currently and can't really afford much more.... Eitherway I think anyone who's found this to work for their 240 AT's should salute you at the minimum and cut you a check or money order for for fixing the problem at zero cost!!!! Again man thanks!!!!! -Dennis "Nframe346@hotmail.com"
Post Title: Re: 94 240 conv with AT shift problems (kc240guy) Posted by:LushPenguin at 8:41 PM 7/22/2007
I said "rockers" photo but I meant yours!!!! Dude that has totally repaired my shift problem at zero cost!!!! Bill me if ya'd like but I prefer to send ya $75.00 in a few weeks when I get paid again... My car was not shifting two or three times in a 5 mile period... I pulled the plug and WOW it runs fine... I've put 80 "city" miles on it in 3 days and it has run flawlessly!!!!
Again thx, -Dennis "Nframe346@hotmail.com"
Post Title: Re: (aradapilot) Posted by:nosferatu226 at 2:17 PM 7/24/2007
aradapilot, where is the tps located? you wouldn't happen to have any pictures would you?
Post Title: Re: (nosferatu226) Posted by:nosferatu226 at 3:38 PM 7/26/2007 ok i got the tps off but i havent had a chance to try it yet because i think my battery is fried...i guess its new battery time
Post Title: Posted by:ishkabibble at 6:27 AM 7/29/2007 Well, I hated the way my car shifted (seemed to sometimes hesitate for a second before shifting, never wanted to let the car rev up, etc.), so I tried out disconnecting the rotational sensor. Shifts much better now, so I'm leaving it that way.
Post Title: Re: (nosferatu226) Posted by:nosferatu226 at 6:34 PM 8/1/2007 ok so i got the tps unplugged and the car started but i'm still having the same problem...no shift until redline. anyone have any other ideas?
Post Title: Posted by:Jesda at 7:16 PM 8/1/2007 Happened to me once. I bumped it into neutral and back into drive, and all was well.
Post Title: Posted by:omg240 at 2:21 AM 8/24/2007 My convertible was shifting the same way everyone elses is. I didnt really know what to do and just found this topic tonight. I found a s14 tranny that shifted perfectly a couple weeks ago and I am having installed as we speak. Am I going to run into the same problem with an s14 automatic tranny?
Post Title: Re: (omg240) Posted by:ishkabibble at 5:41 AM 8/24/2007 If your rotational sensor is bad, probably.
Post Title: Re: (nosferatu226) Posted by:omg240 at 7:32 PM 9/18/2007 Does anyone know Nissan's part number for the revolution sensor?
Quote, originally posted by nosferatu226 »
The tail lights and brake lights stay on when i turn the car off so I have to disconnect the battery when i turn the car off
My vert had this problem. There's a plastic tab on the back of the brake pedal that depresses the brake light switch. If the tab breaks off, the brake lights will always be on.
Post Title: Re: (NISTECH) Posted by:dirtratt at 1:45 PM 10/29/2007
NISTECH I have searched through the posts and cannot find anyone with this problem(96 240SX Coupe) sticks in 2nd gear. I used to turn it off and on and it would clear but that doesn't work anymore. Any suggestions?
Post Title: Re: (dirtratt) Posted by:mazinger-z at 8:03 AM 11/22/2007 my car (90 hatch) problem is not the same as the others in here but may be you guys can help. when is on the D it doesn´t move but it does works fine if i start on 2 it runs first and second fine and then i move it to D and it shift the others fine. so what can be the problem and what should i do? thanks.
Post Title: Re: (mazinger-z) Posted by:alex4 at 10:45 AM 12/16/2007 Yeah, I've been having this exact shifting problem. Wouldn't go out of first sometimes, other than that it's fine. I read this forum and looked at that picture of where to unplug it. Driving home the other day, it would not shift AT ALL. I finally had to just stop and tell folks to pass me. I got out and unplugged it- ran perfectly. Is this a hard replacement? If so, I'll have nissan do it, but I'd rather do it myself. Also how much does a new one cost from nissan? Thanks
Post Title: Re: (alex4) Posted by:ishkabibble at 1:35 PM 12/16/2007 Just leave it unplugged. I've been running mine unplugged for months.
Post Title: Re: 94 240 conv with AT shift problems (oldbald_sarge) Posted by:MXMOVRDV at 6:36 PM 1/27/2008 This article was so helpful and very informative that I feel like ripped some one off by not paying them for it. I followed this article and it helped me to fix my problem. It was a little tough replacing the switch due to very little room beside the trans. Had to take the trans mount off and PUSH the trans side ways to get the sensor out and in. Thank's again for all the info. This is why i became a member. To help out with my knowledge that I have.
Post Title: Re: 94 240 conv with AT shift problems (kc240guy) Posted by:airborne at 4:53 AM 1/28/2008 hey kc240guy,
hey man i will be moving back to KC next year with my 240's. just trying to know some people around when i move back home.
Post Title: Re: 94 240 conv with AT shift problems (airborne) Posted by:airborne at 5:18 AM 1/28/2008
this whole thread has made me scared as crap helped me decide to just change to manual. good thing I have an extra manual tranny and basically everything else on hand except for the pedals.
I bought a 92 convert that i need to pick up in ends of mar 08 and i dont know what kind of tranny problem might have. got it on ebay for 1700 from a dealer. they say it misses a little bit. who knows.
I can rebuild a manual with my eyes closed but an auto, no way. thank god all my other 240's are manual. I cant wait to get back home and get all of them painted, the fast back will be blue and the coupe and vert red. I will post pics when i start doing mods.
Post Title: Re: (NISTECH) Posted by:Seiferliny at 10:26 AM 2/28/2008
Hey guys I'm having some automatic transmission problems. I had just bought a 93 240sx se convertible and on my way home not even 20 mins in the transmission started having problems....
When i test drove it, it shifted perfect....around the same time the transmission started having problems my lower radiator hose split don't know which one occured first guessing the hose.....well i replaced the hose but the transmission is still having problems I didnt drive to far once the tranny started acting maybe a mile or 2 then i pulled over and fixed the hose....and drove it home bout another 5 miles maybe....
Now the tranny is still messed up from what i can tell it shifts from 1st to third because i manually was shifting and i went from first to second and nothing then once i put it into drive it shifted not really sure if its third cause when i down shift to second nothing happens but when i go to first it down shifts and has a bit of leeway when giving it gas before the gear starts to pull when releasing the gas and giving it gas again another weird thing i noticed was when the rpms are getting higher my temperature gauge starts dropping it hits cold then the tranny shifts usually very erratic shifting times sometimes it will do it at 3k lil hard and usually its between 4-5k
I read this forum about the rev sensor and all that i pulled it and nothing changed....
any ideas anyone ?
NISTECH please bestow upon me your great knowledge!
Post Title: Re: (Seiferliny) Posted by:kc240guy at 9:54 PM 3/12/2008
so back in the day i unplugged the rev sensor and went on my way with no issues. now my car wont shift out of second to 3rd at all. it started just shifting late so i thought it was the tps so i unplugged it and it shifted earlier. now it wont shift whether its plugged in or not and when i plug the rev sensor in it doesnt even shift out of first at all.
Post Title: Re: 94 240 conv with AT shift problems (airborne) Posted by:240sxdrifterS14 at 5:05 PM 9/7/2008 Thank you to everyone who helped bring this to an end!!! So far since I disconnected the sensor I have no problems hopefully it stays this way. Finally I have fallen in love with my car.
Post Title: Re: 94 240 conv with AT shift problems (240sxdrifterS14) Posted by:edward08 at 6:48 PM 9/16/2008 I had replace the shift solenoids and i had never had the problems ever again.
Post Title: Re: 94 240 conv with AT shift problems (edward08) Posted by:rcsister4 at 8:18 PM 10/5/2008 I have 2 92 240SX cov. Am new with all this and really learned a lot, pretty over wellming, My red one won't go into overdrive, the O/D light comes on, but that's all. I'm going to try some of the things I read tonight and see what happens. I also love the cars, I drive all kind of cars at the car auctions I work at but there is nothing that is as much fun to drive as they are. Thanks guys http://forums.nicoclub.com/zer...11657#
Post Title: Re: 94 240 conv with AT shift problems (edward08) Posted by:mv520 at 3:57 PM 11/20/2008 is it hard replacing the solenoid?
Post Title: Re: 94 240 conv with AT shift problems (mv520) Posted by:BiXLL at 4:40 PM 11/23/2008 OK, I did the unplug of the Rev sensor and it fixed the shifting problem. Now, has it been decided how long we can run like this without causing other problems? I mean the Rev sensor was put there for a reason, can we run with it unplugged indefinitely?
Post Title: Posted by:mv520 at 9:56 PM 11/24/2008 one question where is the automatic transmission solenoid located at?
Post Title: Re: 94 240 conv with AT shift problems (BiXLL) Posted by:DoctorRobert at 10:03 PM 12/2/2008 Wow. I have had this exact problem with my car. Some days it's worse than others. Well, I just read this and, even though it's 1:01 AM, I had to go try it out on my car. I unplugged the revolution sensor, and took it for a very brief drive. It shifts differently now, but seems to have much better power. I haven't driven it long enough to find out if it's made a change to the shift problem, but I'm really counting on it.
Ok - so I do have a couple questions, one that has been asked before and I've never seen an answer to, and another...
While I do plan on replacing the revolution sensor eventually, it may be a while, so is there any chance my precious will be damaged running it like this?
Other one... Does it decrease gas mileage? One poster I saw said it did with his car, but I was wondering if anyone else found that to be the case. This car is kind of my daily driver currently, and while gas prices have greatly dropped, I do still feel cheap, ha, ha.
Thanks!!
Post Title: Re: 94 240 conv with AT shift problems (DoctorRobert) Posted by:guyaverage at 5:56 PM 12/3/2008
The solenoid(s) is/are inside the transmission, right on the other side of the pan if you remove it. You will have to remove the valve body (not for the faint of heart) if you want to replace all of them. It can be done with the transmission still in the car, though. They do go bad occasionally but late shifts are usually either the revolution sensor or the throttle position sensor.
Driving with the rev sensor unplugged wont hurt anything except maybe burn out your overdrive light sooner. You wont hurt the transmission or computer.
Post Title: Re: 94 240 conv with AT shift problems (guyaverage) Posted by:DoctorRobert at 6:48 PM 12/12/2008
You know the car seems to drive much more sporty now that it's shifting off of the engine RPMs and not the revolution sensor.
Post Title: Re: 94 240 conv with AT shift problems (DoctorRobert) Posted by:speedgods13 at 7:03 PM 3/11/2009 To everyone who has disconnected their rev sensor, I ask you this: Did your o/d light start flashing? I disconnected mine, started the car, and no flash whatsoever. I haven't taken it for a test drive yet, but I will when I get off of work. I don't mind if it fixes the problem, and my o/d light doesn't flash. It would be even better, if it worked out that way. Well, that didn't fix it for me. I'm so pissed. I guess, it isn't going to be an easy fix.
Modified by speedgods13 at 6:54 PM 3/11/2009
Post Title: Re: 94 240 conv with AT shift problems (speedgods13) Posted by:guyaverage at 4:55 PM 3/17/2009 ^^ Yes it may do that because the tranny ECU is detecting the sensor "missing" from the circuit. Not a problem.
Post Title: Re: 94 240 conv with AT shift problems (guyaverage) Posted by:saltfish at 5:00 AM 3/19/2009 This forum is a great service to all Nissan owners...I'm a new owner of a 94 Vert and have been having trans issues (like nearly everybody at one point or another)
The car will drive fine (has a long 1-2 shift but I was dealing with that) then at about the same point in my daily commute the check engine light will go on and shortly thereafter the trans will go in failsafe mode....this sucks to say the least. In the past I have pulled over and put it in park and then back into drive and this has temporaily fixed it. Sometimes the check engine light will go off and other times it won't but it doesn't always go into failsafe but it usually does around 15-20 min into the commute almost always at the same place in the road.
After reading these posts I'm going to try disconnecting the rev sensor but it seems that helped people with the 1-2 shift...what about the fail safe problem? Is there something else I can do for an easier fix? Thanks!
Post Title: Re: 94 240 conv with AT shift problems (saltfish) Posted by:guyaverage at 1:45 PM 3/19/2009
If by long 1-2 shift you mean it holds 1 until too high an rpm before it shifts, thats either a bad rev sensor, bad speed sensor, or the throttle position sensor is defective or out of adjustment. Unplug the rev sensor first.
If by long shift you mean it shifts at the proper speed, it just takes a while to get into 2, thats normal. The 1-2 shift in 240's is intentionally slow to smooth it out. There are ways around that. One involves replacing the 15 ohm dropping resistor with a 100 ohm power resistor (Radio Shack) or better but not as easy, replacing the 1-2 solenoid spring in the valve body with a larger spring from a 300zx or Pathfinder (i'm not sure which one has it but I bought a spare tranny from a guy that had the larger spring and it really firmed up and sped up the 1-2 shift nicely without being harsh.)
Post Title: Re: 94 240 conv with AT shift problems (guyaverage) Posted by:saltfish at 5:29 AM 3/20/2009
I could deal with the long shifts...I can't deal with going into failsafe mode. When it has happened I notice that stopping and turning the ignition off and on seems to fix it. It just sucks when you are on the highway at 6000rpm doing 30 mph with nowhere to pull over.
Post Title: Re: 94 240 conv with AT shift problems Posted by:khmer1 at 6:21 PM 3/26/2009 hey yah im having a shifting problem my transmission doesn't upshift but you can manually shift it(1 to 2 to d but it doesn't feel like it even shift when you put it on D so yea)so it just climbing the rpm without upshifting and slowly gaining speed so i was wondering if this is a same thing as every one problems on it here would it work?but it seems like it from the 91-94 models with the ka24de dohc? would this be the same as the 89-90 sohc version the one with the sohc would it have almost all the sensor from the dohc
btw does anyone have a picture of the location of the rev sensor,the tcu,and maybe other sensor that might be the cause of this problem
and is the rev sensor plug at the same location as the dohc in the sohc..pics would be very helpful thanks
i just change my tranny but that didnt do anything good so now im looking for other causes and if fix it i be one happy sob and wouldnt regret getting my 240sx were i put so much money into just to get it running good
Post Title: Re: 94 240 conv with AT shift problems (khmer1) Posted by:khmer1 at 5:26 PM 3/27/2009
ok so i just got my car back from the mechanic and he said it not the transmission it is something electrical and he said when he took off the tcu/tcm? he said he was able to manually shift from d1 to d2 to d3 and he checked the tcu/tcm opened it and said he didnt see no burnt circuit but had water marks soo any one know what might be the problem?
Modified by khmer1 at 7:59 PM 3/27/2009
Post Title: Re: 94 240 conv with AT shift problems (khmer1) Posted by:khmer1 at 3:45 PM 3/29/2009 bump it i need answers?
Post Title: Re: 94 240 conv with AT shift problems (khmer1) Posted by:speedgods13 at 2:38 PM 4/8/2009 My 240 has this problem. It shift perfectly from 1st to 3rd gear. Now, when going on the freeway, it will only shift to 4th, when the trans is cold. Once it warms up, it will only drive in 3rd. Another thing I noticed, is when it's cold, and I hop on the freeway, if I throttle lightly, it will switch to 4th. When warm this technique does not work. When it's warm, and I try to accelerate, it doesn't grab, and just revs from 2500-3500 rpms, going about 45mph. If I can't find a solution, i'm just going to do the 5 speed swap.
Post Title: Re: 94 240 conv with AT shift problems (speedgods13) Posted by:angHELLic at 12:56 AM 6/13/2009 Hi guys just ran into a problem that i need help with - I have a auto 91 240, 120000 original km's, just had 5 bolt s14 brake upgrade : problem occured while pulling into my driveway, when in park it is impossible to shift into gear without the use of the shift release, drives fine in reverse, but when in D, 1, or 2 car barely moves forward...please help any advice would be greatly appreciated.
Post Title: Re: (AZhitman) Posted by:kosh1986 at 4:19 PM 7/2/2009 iv been having trouble with mine for a couple days now wont shift till around 3 grand rpms think on just doing a 5 speed swap also
Post Title: Re: 94 240 conv with AT shift problems (speedgods13) Posted by:pktj21 at 2:53 PM 8/12/2009 did you ever find out what was wrong because mine is doing the samething
Post Title: Re: 94 240 conv with AT shift problems (pktj21) Posted by:speedgods13 at 6:22 PM 8/12/2009 I've just learned to deal with it, until I swap out the automatic to 5 speed.
Post Title: Re: 94 240 conv with AT shift problems (speedgods13) Posted by:pktj21 at 8:48 AM 10/14/2009 you still having issues or have you figured anything out?
Post Title: Re: 94 240 conv with AT shift problems (pktj21) Posted by:speedgods13 at 1:27 PM 10/14/2009 Have not found a solution to it. Doing a 5 speed swap, and never buying an automatic 240 again, unless I have everything to to the 5 speed swap on hand.
Post Title: Re: 94 240 conv with AT shift problems (speedgods13) Posted by:kc240guy at 7:39 PM 10/20/2009 My old vert had the stuck in first problem so I unplugged the rev sensor and it worked. Then a couple years later it started not going above 2nd most of the time. Since it was rusted all to hell anyway I got rid of it and now I have a rust free 5 speed coupe.
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) so now I'm going to put a DMM on the revolution sensor on the TCM, as suggested, and see what voltage I get when it starts acting up. Has anyone else had a chance to do this yet??? What else can I possibly monitor NISTECH???? We are running out of things to check!!!!!
I will probrably just substitute a less important screw but I just don't want anything to rattle around.
Excellent write up!!! 
This article was so helpful and very informative that I feel like ripped some one off by not paying them for it. I followed this article and it helped me to fix my problem. It was a little tough replacing the switch due to very little room beside the trans. Had to take the trans mount off and PUSH the trans side ways to get the sensor out and in. Thank's again for all the info. This is why i became a member. To help out with my knowledge that I have. 
You wont hurt the transmission or computer. 