OBD! CODE 54: ECM and TCM not Communicating
 

I should have posted this to section, so I apologize for the mis -post inthe main forum. My friend hooked a hand-held diagnostic computer to my car and there were no codes from the the trans. Below is the short version of what I know.

1993 300ZX 2+2 NA AT stock

* Automatic trans will not shift to second except manually bu letting off the gas and then applying at the proper RPM's
* No codes from trans; solenoids are turning ON and OFF when appropriate
* The engine threw a CODE 54 (NISSAN OBD1) "ECM and TCM not Communicating"
* Looked under car and there is a wire that appears to have melted against the exhaust
* Trans is mechanically sound and is shifting, it's just the engine appears to not know what is going on: you can see on the computer that it shifts as high as 4th (cannot go faster than 40-50mph)

I did call a trans shop and they said to check fuses or the harness, but how?
So, my question is how can I repair this without taking it in and how much will it cost me -- how should I go about checking the ECM (I know it is behind the floor board on the passenger side). I have friend that can do the job, but he needs to know what to do.
OR

If there is a good Z Shop or transmission shop in the Bay Area (California) I should take it in to -- got quoted $85 just to look at the car based on all the above info.

FYI: I do have a dealer repair manual, so I can find out where everything is at.


Thanks for any information and help.

well, first things first, if u see something broken, fix it.
repair the wire that looks melted.
Next, DL the FSM and follow the Troubleshooting guide.
Push comes to shove u might need to replace some wires and/or the TCM.

Safe Mode
 

I checked all the wiring and everything looked good: cleaned a few of the, rerouted the wiring and replaced the shielding and nothing has changed.

Now, my battery died a few months ago and I did replace it and I have read that can cause the ECU to go into safe mode, but the vehicle ran long enough to reset anything.

I had another mechanic tell me that the car might be in SAFE MODE since it is not throwing a CODE 55.

How do I go about reseting or clearing the code? There are currently no other codes being thrown. I have seen some information on other sites, butnothing that really explains anythin gin great deatail.

Thank you again for all the great responses.

go to autozone and ask them to read your OBD1 codes. then ask them to clear them.

as for the safe mode deal, i don't know personally but i do know i've seen a thread about it here on z-driver. search and i'm sure you'll find it.