: 94 cadillac sts ECM install

03-08-08, 12:39 PM
anyone ever put a new ECM on a 93-95 northstar. my stock ecm will not fire cyl #6 so i got a replacement on e-bay new and in the box. gm reman #88961146. I put it on and it fires cyl #6 but the trans shifts very hard. So i got a junkyard ecm out of a 95 aurora put my prom in but i get "no pcm data" and the car runs in defalt mode.
I see a ecm at rock auto cardone #778429 for 93-95 caddy northstar and 95 aurora. do i give that a try? thanks for the help

03-08-08, 03:48 PM
Ask ewill or AJ...I''m sure they will come around....

03-08-08, 04:12 PM
thanks I hope one of them will respond. looks like i am not the only one in south west mich.

03-09-08, 12:05 PM
Oh yeah I haven't noticed! :welcome:

03-09-08, 07:34 PM
'94 should have the ECM inside the car right?
Did you swap out the PROM?
You can't just unplug those and plug a new one in, you have to swap the chip out to keep the PROM with the vehicle it was designed for.
There is a cover on the side of the ECM that should have a few screws in it, you just remove that, then push the levers on either end of the PROM, lift it out, do the same on the replacement, then plug the old PROM into the new ECM that is going in.
You should be good after that.

03-09-08, 08:16 PM
ewill3ed I did put my prom in the new pcm. the only think i can think is that both the ecm's i got are bad. the e-bay reman gm and the junkyard aurora ecm? maybe i just need to get one at rock auto.
I looked it up at gmpartsdirect.com (its only 79.91)but i can not get them to verify the part number(if they do not verify the part# you can not return it if it is wrong). I e-mailed them 5 times and can not get them to respond.
I car runs very bad now so i need to get i fixed asap
thanks all

03-10-08, 07:13 AM
Do the part numbers match on both of them?

Do they have red, white, and blue connectors? If so, those are pretty notorious for being junk.
You sure you don't have another issue?

03-10-08, 05:49 PM
my stock ecm is service #16196402. I was told 16180517 16196402 16197429 are all replaced by gm part #88961146. that was the gm reman ecm i got from e-bay. the ecm i got at the junkyard was 16197429 out of a 95 aurora. the interchange at the junkyard told me it would work.
rock auto has a cardone reman ecm part #778429 that is a replacement for 93-95 northstar and 95 aurora. It looks like the best thing to go is get that one. (if the used OBD 1 ecm's are notorious for being junk)
I think the ecm is my only issue due to the fact that the car runs good with the reman ecm in it(it just shifts very hard). then my prom back in my stock ecm and it will not fire cyl #6 but the trans shifts good.
thanks for all the help

03-10-08, 08:51 PM
The new ECM just might need to learn the shift adapts.
How hard is "hard"?
It should mellow out after driving for a while if the trans is the only issue.
The PROM should have the gear ratios and everything essential to make it shift right.

03-11-08, 06:34 AM
you make a good point maybe the ecm i go on e-bay was installed on a aurora and learned the shift adapts of that car . the aurora trans has diff. gears then the STS. (i was told the ecm was new but you never know)

How hard are the shifts - very hard it jolts the car as it shifts I drove it for a day thinking it would learn the new shift values but no luck.

I think i will order one at rock auto I will let you know if it works. thanks again for all the help

03-11-08, 07:06 AM
You are sure welcome. I can't remember how the adapts are stored, especially in an OBD-I computer.
I'd think that a long battery disconnect would wipe them but it is hard to say.

Not sure on all that number changing. I don't have a reference to look any of that stuff up so I'd have to believe those guys when they tell you that.
I hope you get it figured out.

03-14-08, 09:33 PM
I just ordered a ECM from the dealer $240 with core exchange.They went by the last 8 digits of my vin # and said the EProm should be the same.I have a P025

I read about another member replacing his ECM ina 93 and had the same shifting problems.

This is why I went to the dealer if I have a problem he said they would resolve it.But my dealer parts guy goes out of his way to find a part for me.One time he had me bring in a picture of a part I was looking for and showed it to all the mechanics because the parts computer didnt show what I was looking for.

Some dealerships just suck:thepan: