Hello all, first post here, been watching the board here for awhile and decided to join, but anyway here's a current problem I'm having.

('89 GTA 305-TPI 5spd)
Car runs like crap until it warms up (usually about 3 minutes)
No trouble codes
Scan Tool displays "Vehicle not Responding"
Jumping pins A&B on the ALDL gives a code 12 (good)
Good continuity and no grounds between ECM connector and ALDL connector. (I've even tried hooking up right at the ECM)

Anybody else ever run into this? ECM? PROM? Both? Other?

I'm assuming that when it warms up the O2 sensor kicks in and then everything is alright. I know I probably have another problem somewhere, but right now I'd just like to get my scan tool to work on this vehicle.

Also as a side note, the PROM ID# is 16129401, and it is the '165 ECM which is the right ECM for this vehicle. But I don't see that PROM# listed in the database here. ???

I'm open to ideas, but I hate replacing things that don't need it (don't we all)

 

Well if anybody's interested I finally went and got a new (well, reman) ECM, transplanted the PROM and my scan tool works now, my erratic idle went away, my driveability is much improved and my performance is back where it used to be a couple years ago (and it only cost me $80).

 

Glad to hear it. Sorry you didn't get any replies.

 

Now this car is pissing me off. It worked for 3 days and then it ran like crap on the 4th day, got out the scan tool and guess what - "Vehicle not responding" I said ****it and left it sit for a couple days. I went out yesterday and checked it with my scan tool, worked great, started up and ran great. ???? Then I shut it off and tried again - still ok. About the 5th time I cycled the ignition switch I got "Vehicle not responding". Then all I did was turn the ignition to off and back to on and it scanned ok. I tried putting my original ECM back in and couldn't get it to scan at all (same as before), put the reman unit back in again and it scanned fine the first couple of times and then it crapped out again, cycled the ignition and it came right back.

I know there's something different between the original and the reman. Is it possible that the reman has an intermittent version of my original? I sort of doubt it though. I'm thinking that there's something causing it to be this way but I can't imagine what external component would cause it to not scan, not set any trouble codes (except 12), and run ok when it is warmed up. PROM???? Severely frustrated.......

 

make sure all your grounds are good, Specifically those behind the intake my the distributor. that is where the ECM is grounded AFAIK.

had a similar problem on my blazer, intermittant ECM failure.

Turned out to be a shonky ground.

 

I checked the ground at the ALDL which is fed by the ECM and it seemed alright, but I didn't check where the ECM gets it's ground from. I'll check that probbaly this weekend, thanks for the tip.