1992 240 SX Convertible - Auto Trans. stays in 3rd gear.

[09quickly]

Outside now attempting voltage tests. Some questions:

Is the A/T control module the brown receptacle located behind the glove box? If so, I found it, disconnected it, and now have easier access to the ECU.

When accessing the pins to test, where do I place the black lead for a ground?

I have found the light green wire with the red tracer, it is the only one I have been able to locate. Pin 35 should be a black wire with silver dots, or completely black? I have been able to locate only one white wire with a blue tracer, but it is nowhere near the other wires, it is more in the middle of the blue receptacle.

More rookie questions:

I have disconnected the ECU to gain access to the pins, but if I'm testing the ECU, this makes no sense. Do I re-attach the ECU and gain access to the pins some other way? Take the back off the ECU?

Also, I drove the car around the block yesterday, barely. Started fine, idled fine, ran like it was firing on two cylinders when I gave it gas in drive and reverse. It would not go up a slight incline in my driveway. After warm-up, smoothed out for a short distance, then ran like Sh*t again. I live on a hill, and people walking their dogs werer going up hill faster than I was. Did another self-diagnosis of the ECU again when I got back to the garage and .....55's!!!!! What up?! 09quickly

[NISTECH]

Outside now attempting voltage tests. Some questions:

Is the A/T control module the brown receptacle located behind the glove box? If so, I found it, disconnected it, and now have easier access to the ECU.

When accessing the pins to test, where do I place the black lead for a ground?

I have found the light green wire with the red tracer, it is the only one I have been able to locate. Pin 35 should be a black wire with silver dots, or completely black? I have been able to locate only one white wire with a blue tracer, but it is nowhere near the other wires, it is more in the middle of the blue receptacle.

More rookie questions:

I have disconnected the ECU to gain access to the pins, but if I'm testing the ECU, this makes no sense. Do I re-attach the ECU and gain access to the pins some other way? Take the back off the ECU?

Also, I drove the car around the block yesterday, barely. Started fine, idled fine, ran like it was firing on two cylinders when I gave it gas in drive and reverse. It would not go up a slight incline in my driveway. After warm-up, smoothed out for a short distance, then ran like Sh*t again. I live on a hill, and people walking their dogs werer going up hill faster than I was. Did another self-diagnosis of the ECU again when I got back to the garage and .....55's!!!!! What up?! 09quickly

I am thinking you got the wrong connector or something. However your tests will be with it plugged in you will be testing it in operation. You back probe the terminals with a paperclip or t pin. You may have to pop off a sheild that covers all the wires on the connector. Here is an exact picture of the A/T control unit. I do not know off hand what color the connector is. But it should have a 10mm bolt holding it into the control unit.

[09quickly]

Okay - Results of tests - Does not look pretty. I loosened and removed the A/T box, found the green-red, white-blue, and black wires (I thought these wires were on the ECU, that's why I was scratching my head). The brown electrical plug I was talking about earlier is next to the blower motor, and wires from it go to the ECU. Anyway,

Red/Green wire on A/T connector - .394 to 1.3 volts AC, fluctuated quite a bit, then settled at 1.3. White/Blue wire - .321 volts to 1.17 volts AC, settled at 1.17. Black wire - 1.158 volts AC.

I forgot if cars are measured in Direct or Alternating current , so I did both. 0 volts DC on all except the black wire, started at 2.7, settled at 0.

[NISTECH]

voltages are measured with DC. You should have the key in the run position when doing this test. If you are not seeing 5 volts on the light green/red wire in those conditions you need to go directly to the tps and find that same color wire and check for 5 volts. Right now this is your primary wire to check. Sounds as if you have a good ground but you are not recieving the 5 volts in the line. You are testing with the connector plugged into the A/T control unit right?

[09quickly]

Yes, I'm on the A/T module now, at first I wasn't, and that was part of my confusion. Key was "on", and I used your suggestion about the paper clip. Naturally, the wires I needed access to were the hardest to reach, but I think I had th paper clip in the correct slot for each wire. I will redo the test just to be sure. Where is the TPS located? Should I be concerned about my other "0" readings? 09quickly

[NISTECH]

no the other reading is expected to be zero if that one is. That 5 volts is cut down by the resistance in the TPS , the tps sends what voltage remains back to the ecm then to the TCM on that wire your seeing 0 on. You need to figure out why that 5 volts reffrence is not there. The ECM supplies that 5 volts. It goes both to the tcm and ECM. Since the ECM is not throwing a code for TPS I am thinking you have the voltage at the TPS but you need to test first to find out. The tps is attached to the throttle body. There is a grey connector strapped to a hose right next to it. There should be 3 wires in that connector 2 of them will be the same color as the ones at the TCM. Find that same color wire and check for voltage.

[babowc]

didnt read up on what nistech and others had to say..but my brother had the same problem on his 2002 elantra.it was a sensor that was fried.it'd work sometimes and sometimes not though..he replaced it, its driving fine now.hope this could help

[09quickly]

Redid the A/T module test tonight. Still 0's for DC voltage. Found the TPS connector on the intake tube, and the three wires you mentioned. Light green w/red tracer, black, and white. 0 voltage at green/red and black wires, key on, engine not running. 09quickly.

[NISTECH]

Odd your ECM should be throwing a code as well. You need to get to the ECM and check for power at that same wire at the ECM terminal 37.if your looking at the connector while its plugged in it is the 3rd slot from the right in the top row. The top row is the side with the rasied section where the bolt is. That wire will be the same color there as at the TCM and TPS. See if you have the 5 volt reffrence there. If not I am going to have to find another 5volt reffrence for you to tap into to see if you can get this circuit live to see if the rest of the circuit is ok.

If you found that circuit does not have a 5 volt reffrence at the ECM then that means the ECM has failed internally and is not supplying that voltage. That is when we are going to try and find an alternate 5 volt reffrence to tap into to get that circuit going. If It works you should be able to run with it like that.

[09quickly]

I will double check everything again next chance I get, I hope that I have been getting good contact with the paper clip when I jam it into the backs of the wire receptacles, it usually feels pretty secure, I just can't see a metal to metal connection. I will get another opportunity on Thursday, hopefully. I have to go to Atlanta tomorrow. 09quickly

[NISTECH]

At the tps unplug it and test the wire from the terminal side to assure you are getting good contact with it. Your key must be on. That wire should have voltage weather its plugged in or not when the key is on. Do that first just to be sure there isnt power on that wire.

[09quickly]

Okay, here we go - I re-did the tests you walked me through earlier. It is amazing what a multimeter will tell you when used properly. I stopped using the paperclip for a lead, and I started using the black lead on a good ground point. Go figure.Key on:

Terminal 31- light green with red tracer - 5.12 volts DC Terminal 34-white with blue tracer -.324 volts DC (idling)Terminal 35 - black -.005 - .002 sporadic volts DC

ECU - Light green with red tracer - 5.12 volts DC

TPS -plugged in, key on.0 volts at rear of wire leads.

receptacle leading to TPS plug -plug leading to green/red .354 to .400 volts DCboth other leads - .250 -.350 volts DC

Idles rough when it will run.

[NISTECH]

Ok so your saying you have 0volts on the lg/r tracer wire at the tps?? all your other readings at the TCM look ok with the exception of the reading on terminal 34. It could stand to be slightly higher at idle. regardless tap into terminal 34 again , with engine off key on press the accelerator pedal slowly to the floor and back up. What does the voltage on terminal 34 do?

[09quickly]

Key on, white/blue on the TCU:

.327 volts, no accelerator

Climbs to 2.8 volts when accelerator depressed, also heard a buzzing sound from the engine as the accelerator went down slowly, stopped when the accelerator was fully depressed. 09quickly

[NISTECH]

you have got a connection issue somewhere. That voltage should have climbed to over 4 volts when the pedal was fully depressed. how is the terminals in the connector at the tps? also recheck that same color wire at the TPS when you do the sweep. Check the 5volt reffrence at the TPS too. Make sure its there.

[09quickly]

TPS - 5.2 volts at the metal lead for the green/red in the receptacle.TCU - white/blue - still the same after cleaning receptacle, checking for secure fit.ECU - white/blue - .329 volts, same as the tcu before depressing accelerator.

[09quickly]

P.S. - battery is starting to die, I have it hooked to a charger at full charge when I run all of these tests. 09quickly

[NISTECH]

Ok your next test is to be done at the signal wire on the TPS. Your conducting the same test you did at the white with blue wire at the TCM and ECM. See what the voltage is at rest and then slowly crank your throttle drum around and watch that voltage. Does it show the same voltage you saw at the TCM when you rotate it? Does it too stop at around 2.8 volts? If it does you need a TPS. If it doesnt and it climbs to over 4 volts you are going to have to trace down the circuit back to the ECM and see if there is a connection problem in the circuit somewhere. Before condeming the TPS also check its ground circuit with the key on and see if you have any voltage on that wire. You will be doing both those checks with the TPS plugged in and the key on.

[NISTECH]

Its gonna be the white wire on the TPS for signal and the black wire for ground.

[09quickly]

Cleaned the connections on the TPS, had to go back to the paperclip to try to get a good connection.

Black wire - .0011 volts

White wire - starts at .3 range, flirts with 4.0, but is sporadic, hangs mostly with the 3.4 - 3.6 range, nothing steady. 09quickly.

[NISTECH]

does the black wire change when you move the throttle. The voltage you have on it at rest is really good. Means you have a good connection to ground. if it pretty much stays in that range when you rotate the throttle then that proves your ground is good. The white wire needs to steadily go to over 4 volts as you slowly crank the throttle drum around , if it cant the tps is junk. Just make sure you have GOOD contact with the back of the pin when testing it. I dont use a paper clip for testing at work, I got a box of Tpins from staples since they can get in there much easier. Most people dont have those handy so I tell them to use the paper clip method. Just FYI incase you do got some.

[09quickly]

I re-did the test from earlier today. The black wire stays at a steady .0011 volts as the trottle mechanism is rotated around. The white wire is sporadic, .257 - .436 volts at rest, and then an uneven, sporadic climb to 4.00 volts as the throttle mechanism is rotated. Rarely going over 4.00, usually topping out there then dropping into the mid-3's. Again, no steady, constant readings on the white wire. 09quickly.

[NISTECH]

Replace the tps and set it for .45volts on the white wire. You should be good to go after that.

[09quickly]

I will order a TPS from the autoparts warehouse tomorrow online. With the holiday this week and travel plans, I may not get a chance to install it until Saturday. I will definitely let you know how it turns out. Many thanks again for your patience and expertise. I could not have gotten this far without you. 09quickly

[09quickly]

Installed the new TPS today, the old one had some severely corroded contacts on it when I finally got it off. Naturally, I ran into some issues along the way:

New TPS is on, spring loaded cam is in place with a little bit of tension. 5.2 volts on new connection with key on, not running. I assume adjusting the TPS is accomplished by moving it in place and adjusting the spring load on the cam inside.

Will not run, starts with difficulty, must hold accelerator at 2000 rpm or more to get it to run smoothly. Otherwise, sounds like it is firing on two cylinders. Can not adjust the TPS because it will not idle.

ECU code - 34 Detonation sensor circuit. Where is this one?

Also, in my haste to pull the upper radiator hose to access the TPS, I spilled anti-freeze into the throttle body chamber. Don't know how much, not sure if this is causing my starting and firing problem. This will probably lead to catalytic converter issues if it is too much, but I guess that can be addressed later.

[NISTECH]

when you put the tps on you will rotate it in so the spring of the sensor pushes aginst the throttle shaft tab. Once you have it in place so you can start the screws you use a volt meter and measure the voltage on the white wire so it reads .45volts or as close as you can get to that. then tighten the screws so it will hold that position. Your run problem does sound like you got quite a bit of coolant in there. Tps wont cause that. Take the spark plugs out and clean them off. Crank the engine over with out the plugs in to blow as much coolant out of the cyl as possible. The coolant is less detrimental to the cat as it is to the O2 sensor. We will see how it fairs up when your done clearing the system of coolant and getin the o2 set.

The knock sensor code may have been set when you removed the tps. There is a 2 wire connector near the front of the cyl head right above the water inlet. If you disconnected that it could of been what set the code. Either that or the connection is corroded similar to the TPS connector.

[09quickly]

Okay, followed your previous instructions-Set TPS at .453 volts, tightened it down. Reconnected all of the hoses, air intake tubes. Three connectors you mentioned in front of water outlet - cleaned them, reconnected. Removed all spark plugs, cleaned them, cranked each cylinder to push compression and hopefully moisture out. Started it and ....RAN!! SMOOTH!! Let it idle, cleaned up tools, went for a drive in the rain and,... same old sh*t! Stuck in 3rd, and the longer it ran, the worse it ran. Had to keep it above 1500 rpm to get any semblance of "smooth". By the time I got back to my driveway, I was lucky to limp back into the garage. ECU check- 55's!!! 09quickly

[NISTECH]

is the od light flashing again? if so do the test procedure again and see if your still getting a tps code. Also check the terminals in the TPS connector,1 see if they are clean if not clean them with some battery terminal cleaner or bakingsode/water mix. 2 try gently bending the female terminal in the connector toward the center of the opening slightly to get a better contact with the tps terminals.

[09quickly]

O/D light will not flash. Comes on for 2 seconds, then goes off. Does nothing once the self-diagnosis sequence is complete.

Car started fine (cold), and as it warmed up, a miss developed, getting more severe. As the rpm's went down to 1,000 rpm, an occasional miss, drop to 975 rpm, severe miss. Needs accelerator to smooth engine out.2,500 rpm smoothes everything out. At operating temp., 1,300 rpm is smooth, but needs accelerator. Letting off accelerator allows engine to lug, then stall. Will not idle on its own at operating temperature.

The replacement TPS appears to have the identical connector as the old, but will not plug all the way into the receptacle on the engine like the original one did. It will not go all the way to the plastic lock on the receiving receptacle. I assume good contact, because 1) No longer have the O/D light flashing and 2) great improvement over how it ran before (initially) when I finally got it started again. After attempting O/D self-diagnosis, checked the ECU.....55's. What about dirty fuel filter or dirt in the fuel pick-up in the tank? Am I considering "What if's" in the wrong area? 09quickly

[NISTECH]

You have a large vaccum leak. check your intake hose and make sure it is correctly mounted to the throttle body and there are not splits in the hose, check the hose under the intake tube that goes to a baffle thats mounted to your radiator fan shroud. Its on the same side of the fan as the throttle body. Make sure it is connected properly.

The TPS connector: unplug it and make sure you dont have 2 rubber seals in there. There should only be one rubber seal in there. If the OD light is off you are likely correct that the connection is there. Your car should be shifting ok at this point. Get the vaccum problem resolved. It has to be where you were working as it wasent a problem before. You had to have knocked something loose unknowingly in that area.