Saddles

iTrader: (2)

Hate starting a thread, but I needed some reassurance from the guys here at the .Org.


I am receiving a vehicle speed sensor code and a revolution sensor code when I run the AT diagnostics as outlined in the FSM.

In turn, there is a ghost code on the ECU of 54, which refers to the signal from the TCU to the ECU.

From the threads I've dug up, I am a bit torn on how I should go. Some suggest that if you receive VSS and 54, you should replace the TCU.

Others suggest that the VSS code and Revolution sensor code may be causing the 54 code on the ECU.

Has anyone been in my shoes? I will test the revolution sensor asap, but other than checking wiring between ECU and TCU I am unsure of another way to see if TCU is actually failing other than to swap it.


I should note that only problem this causes is that sometimes the car will not shift into OD. If I shut the car off, restart it, and take off again usually it will shift to OD with no issues. There doesn't seem to be any hard shifts or slipping occuring.

2brosgixxer

What year car are we talking? Your info shows you drive an 02 but you posted in the 4th gen section.

Saddles

iTrader: (2)

Sorry

This is my 95 gxe I'm referring to. 183k on it.

KRRZ350

iTrader: (29)

IME only a .001% chance it's a bad tcu. The sensor is hard (impossible) to test without an oscilliscope, so I would just go ahead & pop off the driverside wheel & splashield & replace it, but before you do that check for bent pins at the connector, it's on the top of the trans & likes to seize together making it a nightmare to disconnect. Just fixed that code from a bent pin 2 weeks ago.

Saddles

iTrader: (2)

Thanks a lot...always appreciate other's experiences, no better way to learn!

So it is necessary to remove the wheel and liner to access it the most easily?

Were you experiencing any issues similar to what I was seeing? Did you have the accompanying vehicle speed sensor code/ signal to ECU? I understand rev sensor is the one in the transmission and speed sensor is at back of cluster, so you must of worked on your revolution sensor correct?

I don't mind buying parts - just trying to fix this car cheap as possible and trying to get all P's and Q's lined up before I order.

Thanks for help!

Saddles

iTrader: (2)

OKAY. So I ordered a VSS and installed it, didn't have 3rd gear right off the bat so I'm thinking no dice. Well next day I had no speedometer and short story is the VSS I put in shelled out. SO I got to return it and try it as a possible solution free. Good deal.

Since signal is obviously making it to the cluster, but I am getting codes for revolution sensor and vehicle speed sensor motor, I am thinking that the cluster is not passing the voltage along to the TCU and ECU thus causing issues and setting the codes. I am not sure however if data exchanged between the ECU and TCU passes through the cluster to explain the 54 code.

Does this make sense? I guess my next move will be to pull the cluster and tighten connections at the speedometer. Worse case I guess I can order a cluster.

vqmaxman

The VSS is just a sensor for the speedometer and the sensor senses the speed from the tranny to the speedometer. The wires are connected to the ECU and to the TCM. The revolution sensor senses the trannys speed to the TCM. The best solution for you is to test the sensors out and check for the voltages. If the voltages read out ok as it's stated in the FSM than there ok get the TCM/ECU tested they can be faulty. The speedo is still acting up when you changed the VSS, than you have to chech the cluster out and change out the circuit board or the speedo needles.

Saddles

iTrader: (2)

So basically if my speedometer is fine (which it is) my VSS is working. Which is why I was confused as to why I had a code on the ATCU for 2nd flash longer than others, which FSM states as being vehicle speed sensor circuit...the page the chart defines references this code as being for the VSS MTR which is contained in the cluster. My thought is that the signal is not being relayed to the ATCU/ECU from the VSS MTR in the cluster. I know the guide is there to test for this and I plan to, however, a lot of posts point to broken solder joints in the cluster, which needs to come out to test this anyway, so I plan to check there first. Some posts made me believe the code 54 may be directly related to this but others as you state, this is a problem with a connection directly between the ecu and atcu.

I believe I understand the revolution sensor (1st flash longer than others) to be completely different and seperate from the VSS, but from the images, seems to be contained in the same general area as the VSS and is the one without a gear of any sort attached. I had read different procedures to replace the revolution / vehicle speed sensors and one said to remove the wheel and fender lining, and so I believe the sensor that must be accessed in this method is the one I truely need to look at/ test the harness for/ etc.

Just ignorance at its best on my part there. :/

DennisMik

iTrader: (2)

The 0504 blink code translates to P0600, A/T Control Unit.

The ECM continuously receives incorrect voltage from TCM (Transmission Control Module).

Possible causes:
Harness or connectors (The circuit between ECM and TCM (Transmission Control Module) is open or shorted.)

TCM (Transmission Control Module)

Saddles

iTrader: (2)

Welp! I went for it and bought a TCM from Maxima_Joe. I've had 4th gear everytime since I replaced the TCM. Transmission diagnostic is showing only the code for the VSS Motor Circuit (2nd flash is longer than others) and I believe this is the code that can be fixed by resoldering / tightening connections at the speedo in the cluster? Code 54 has disappeared from the ECU and is showing 55 all clear each time.

Well Its turning out okay. I've got maybe $1000 in the car now, some of that being frivolous expense (radio, new door panels etc) bug I am glad I picked up the 4th gen. Always missed my old white one and while I no longer have a MEVI, 5spd, drop....I gave up a lot when I sold my white car...I am still enjoying cruising the highway in my 4th gen.

Still gotta do lower control arms, shocks/struts, and at least a muffler. My roommate is a body man so we're pulling the dent out of the fender and installing all the great parts I bought from maximabebe this weekend. As well as rubbing compound / polishing compound / a coat of wax and a super wash inside! Should be looking good!!

Thanks for everyones wonderful advice and assistances! Maxima.org revived this car!

Saddles

iTrader: (2)

....I see why people don't update their threads... It's back. First trip in the car this morning - same old same old - no 4th gear. I rechecked all the codes and they are all back. 1st and 2nd flashes longer than others (Revolution sensor, VSS Motor) and code 54 for signal to ECU again on the ECU.

I didn't think the transmission computer was THAT smart, as in, that it look time for it to learn the car etc. After 2.5 days of driving without issues and only 1 code (I checked it damn near every time i parked just to see if the repair was working) and then to have them all back, could something be burning out TCMs?

:/ Back to it I guess. Time to ohm and test voltages? I still have a revolution sensor I haven't installed yet, I guess I could try that. I don't like guessing and I'm getting above head in car tech.

Saddles

iTrader: (2)

The more I drive it....

It seems that most of the time, the car is fine. It shifts as it should, RPMs seem normal etc. When it is going to have this issue: When I first take off it feels like I need to give it a little extra gas, like the car is not starting from first gear. I always backup before I go forward when leaving in the morning, and reverse causes no issues. When I pull forward again, it feels like I am in 2-3gear trying to start off. Then, when I hit black top, I can feel the shifts to 2nd, then 3rd, then the car just keeps revving up. Any RPM less than 3k does not speed the car up or allow it to maintain speed, is this slipping? If I take my foot off the gas, it will drop all the way down to idle RPMs - a bit higher at 1100-1300. If I rev back up, the car does not seem to increase in speed or maintain speed until I hit 3000rpm again. I usually pull over, shut the car off, start it back up, and when I take back off the car shifts out all the way and feels like it is starting from 1st from a dead start at this point and usually behaves normally for 2-3 days until I have to repeat.

I am going to check connections to the revolution sensor. When I changed it, I did not have the rev sensor code for 3-4 days. Then it came back and is on after every trip again. This is the same behaviour I experience when I changed my TCM, and then after I put my original TCM back in.