Auto transmission Guru's Have Q's

[tim]

I am very green on Nissan and have a few questions. I bought a '91 240sx and the car only has reverse and first, does not act like it wants to shift into any higher gear. I drove the car with the shifter in drive and went from idle to around 6500 rpm both easying into the throttle and actually "kickin it" and no difference. No slipping, no going into 2nd and not pulling, just will not shift out of 1st. The guy that I got it from bought it that way also and has the same opinion on the shifting. A previous owner had cut the shifter and put a noen handle on, he cut the wires to the od switch for power to the bling bling shifter handle and the handle does not have an od switch. I removed the shifter and after getting it out was moving the rod that goes from the shifter to the trans and noticed that it would not engage in the low gear posistion.Seemed like something was pushing it back out of low. kinda felt springy when pushing the rod into 1st. Rest of the shifts felt fine So, my questions are; 1.Could the wires on the od being cut have caused the shifting condition either immediately or after prolonged use with the wires cut? 2.Would not being able to get the shift linkage to stay in low gear as discribed above cause the shift problem? 3.What other than replacing the shifter needs to be done to isolate the problem? I apoligize for the long post, just didn't want to leave anything important out .

Thanks Tim

[NISTECH]

your problem is not related to the shifter you have something more going on in the trans either valving or trans controller.

[tim]

By trans controller do you mean aome kind of computer located outside the trans? If so where is it located?

[NISTECH]

yes its located near the engine control module on the right side of the passenger compartment.

[tim]

Can you post a pic or a link to give me an idea of what I am looking for? I have searched the net and have not found anything. maybe just tell me what it looks like. I'm sorry about being so green. I bought this car as a first car for my 16yr old and I am trying to learn as cheaply as possible

[NISTECH]

this is out of a 94 S-13 but should be the same location.

[tim]

Well I'm getting conflicting info on this. Nissan parts says that the '91 didn't come with a "shift controller " another parts store also said this then called me up to tell me it was under the center console behind the shifter. There is a box with a lot of wires there, could this be it? Any other thoughts? Boy I can't wait to get a TSM.

[NISTECH]

do you have air bags? that might be the airbag module if it has yellow connectors.

[tim]

Well it's been a few days but I got a shifter put in the car and ran the self diagnoses prosedure (without consult) and the light does not come on, tsm says tells what else to troubleshoot but I can't find anywhere in the tsm that tells how to get to the transmission controller so I can do the troubleshooting. Can you tell me what has to be removed to get to it or where the tsm tells how? The tsm I have is for a '93240sx.

[NISTECH]

you should be able to pull the glove box out and see it.

[tim]

I can see it just don't know what I have to remove to get at it so I can run diagnoses as tsm suggest. Will I have to remove blower motor? anything else? When I do get the A/T control unit out where I can run test, will the unit need to be grounded exturnaly?

[NISTECH]

no It wont you can lay it on the floor or let it hang It is not externally grounded.

[tim]

Ok, after running diagnoses according to fsm O/D does not come on. Says to go to inhibitor switch,overdrive switch,throttle position switch circuit checks. This is what I got. '91 240SX NISSAN Battery volts at time of test ; =12.39v

Inhibitor switch check; P/N=11.25v R=9.68v D=11.39v 2=11.52v 1=11.52v

O/D switch circuit O/D on=8.70v O/D off=8.70v

Kickdown switch circuit Before pressing pedal= 4.75v While pressing pedal= 4.75v Pedal fully pressed=0.00 While releasing pedal=4.75

Closed throttle position switch circuit Bofore pressing pedal=11.35 While pressing pedal=0.00 Pedal fully pressed=0.00 While releasing pedal=11.35

The things I found odd were the voltage #'s in general and the O/D switch circuit testing the same voltage in the on and the off position. Would either of these things not let the transmission shift out of 1st gear? Could the low voltage #'s = a bad A/T controller? Could you give me your thoughts on this and where you would go from here?

[tim]

Bump; Could really use some input here.

[NISTECH]

I am not familier with those tests you performed but judging by what you came up with on those switchs you likley didnt measure them right. It makes no sence that your over drive voltage was the same with the switch on or off and that most of your gear selection measurements matched your P/N measurements.

Your kick down and closed thorottle switches look like they are working by your tests.

I suggest you carfully go over the test procedures again and redo the test on the inhibit switch and over drive switch. on the od switch just uplug its harness at the shifter and use an ohm meter on its 2 wires when pushed you should have continuity when released it should be open.

[tim]

These test were run according to instructions from a '93 240sx FSM without consult. I used a digital meter and run the test two different times, double checking the results the last time. Basicly measureing volts at the a/t controller by probing the called for pin and ground. Don't know if I can legally post the instructions I am using but if you want to have a look I will email them to you.

On another note I am not sure if the car sat without batt. power for a long period or not before I got it, Would this screw anything up? Sorry about being so green. I will look at and do the test again this weekend.

[s13sr20chris]

your kickdown switch voltage is out of spec but i dont think it is far enough to cause your problemjust to eliminate it break out your jumper wires. jump od switch voltage to tcm pin 41. that will simulate a fully functional kickdown switch that is not kicking down. your od switch is def inop but that wont keep it our of first. your voltage for reverse is wrong but that should not be a prob. if anything that may be an indicator of tcm health. any corrosion on the tcm?

**dumb question**any fluid on the dipstick with engine running?

[s13sr20chris]

if fluid is ok then do this. unplug tcm alltogether and drive around. the a/t should be mechanicaly limited to 3rd gear. this will be radicaly different from what is has been doing so far. that is "fail safe mode". if prob persists then it is a mechanical prob and not electrical.

[s13sr20chris]

one more thing. please perform a stall test. just put in drive, stand on brake, and floor gas pedal for about 3 seconds. look at what rpm it holds during this time. what is it?

[tim]

s13sr20chris, the FSM indicates that the volts should be between 3-8 volts for the kickdown switch test, is this right? Exactly what am I supposed to look for when I use the jumper as instructed above? Should I drive the car to see what it does then or what? I haven't checked fluid while running yet but did check to see if anything was wrong with it. It looked good,smelt fine. Will difinantly check while running next time. I will try to do the stuff you ask sat morn. and post asap.

[s13sr20chris]

hmmm, 3-8v ok? i dunno. i dont do a whole lot of a/t diag at the shop. if you jump it and the kickdown circuit is the prob it will drive fine.

[tim]

fluid level is fine with motor warmed up and running. didn't use the jumper yet, still not sure exactly what i'm supposed to hook to at the o/d, the button on the knob or the thing the wires run to from the button? If the o/d switch is bad then wouldn't that have an effect on the diagnoses procedure since you have to turn it on and off at various stages in the process? no corrosion on the tcm. tried to do the stall test but brakes are shot and the wheels would spin. unhooked the tcm and drove but I couldn't tell any difference from when I drove it before unpluging it. would really like to know if the o/d switch had any effect on diagnoses and where can I get one, napa, aotozone, or is this a dealer only item?

[s13sr20chris]

well, it aint looking good. if you tried a stall test and the brakes would not hold, then your brakes may really suck or the stall may be way too high. does not really matter, heres why. if you unplugged the tcm and it drove around in first, the trans is blown. sorry. without the tcm to command gears, you are stuck in 3rd. if that dont happen, its internal. the o/d switch can only keep you in/out of 4th gear. if you want to try jumping it still, just jump it from anywhere you can find 8v. its the 8v i want to get jumped over there. does not matter where it comes from. that 8v will simulate a fully functional kickdown switch to eliminate it as a source of probs. however, we already know the prob is internal.

[tim]

Ok I give I'll try to get a transmission. Now about the O/D switch since we know it is bad too, is it the little white box mounted on the pass. side of the shifter? If that isn't it, where is it and where do I get a new one? Parts store or is this a dealer item?

Thanks again for you guys help. I'm sure this is not the last time you'll be hearing from me.

[s13sr20chris]

it should be a little button on the shifter.