PCM 92 yukon

[Jason Warrum]

Ok guys and gals. The tinkerer is back. So I had an issue with my 92 Yukon 5.7, it was idling high and then it was shifting funny. Missing shift points/rpm as far as I could tell. Well I took it to a shop just to have diagnosed because I was thinkn vacuum leak somewhere and I couldn’t find one. So shop did diagnostics said no leak, no codes no recent codes and couldn’t find anything obvious. Stated leaning towards a bad PCM. They rrefered me to another shop who specializes in older classic cars. So couple questions…….

1) Are those typical symptoms of a bad PCM?

2) typical cost for new flashed/programmed/ PCM if in fact that’s what it needs? Just average ballpark cost

3) is the PCM just like a plug and play type thing or is this something that’s a legit job to replace


Just tryn to get ahead of whatever I need to to get my truck running like a top…!!! Thanks all!!!!

 

[evilunclegrimace]

The '92 has an ECM .There is a bit of diagnostics to be done before swapping out parts. The ECM does not control the trans. There are FSM that can be down loaded for free here on the forum. Look at them and follow the diagnostic tree. Nick from Nicks Transmissions has a thread on 4l60 trouble shooting in the Transmission section.

 

[DonYukon]

The '92 has an ECM .There is a bit of diagnostics to be done before swapping out parts. The ECM does not control the trans. There are FSM that can be down loaded for free here on the forum. Look at them and follow the diagnostic tree. Nick from Nicks Transmissions has a thread on 4l60 trouble shooting in the Transmission section.

HE is correct. And from what i can recall 92s have a 700R4 which means that trans has no electronic shift controller of any sort it uses pressure and a cable system Cant remember what its called. however if the engine is acting up it may very well affect the transmissions shift nature.
(Edit I actually cant remember if they had the 4L60 or the 700R4 ... but im pretty sure the E model didnt come out till like 94)

 

[Jason Warrum]

Ok. Thank you guys. I’m taking it to another garage and gna have them diagnose This issue is beyond my auto mechanical knowledge.

 

[evilunclegrimace]

HE is correct. And from what i can recall 92s have a 700R4 which means that trans has no electronic shift controller of any sort it uses pressure and a cable system Cant remember what its called. however if the engine is acting up it may very well affect the transmissions shift nature.
(Edit I actually cant remember if they had the 4L60 or the 700R4 ... but im pretty sure the E model didnt come out till like 94)

It is called a Throttle valve cable,and it is a 4l60 in '92

 

[Jason Warrum]

Does anybody wanna let me know how ECM is changed/fixed??? Just basic explanation? I understand you have to reprogram and reset some codes?? Just tryn to learn and understand Like I said this is beyond what I know but I wanna understand/learn.

 

[evilunclegrimace]

Does anybody wanna let me know how ECM is changed/fixed??? Just basic explanation? I understand you have to reprogram and reset some codes?? Just tryn to learn and understand Like I said this is beyond what I know but I wanna understand/learn.

You do not have to reprogram a ECM for your truck. You do have to swap the mem-cal and PROM from the old to the new.

 

[Jason Warrum]

You do not have to reprogram a ECM for your truck. You do have to swap the mem-cal and PROM from the old to the new.

What if I bought a new one already flashed to my vin? Is it just plug and play after that. Again I’m just tryn to learn.

 

[evilunclegrimace]

What if I bought a new one already flashed to my vin? Is it just plug and play after that. Again I’m just tryn to learn.

There is no reflashing for your year truck. Match the ECM number and swap your old PROM and MEM-CAL to the new unit