Hello, I recently picked up a 1991 z28 305 tpi that had been sitting outside for the last 17 years. I am currently in the process of trying to get it running and am questioning a bad ecm. I have noticed that the ses light doesn't turn on under any circumstances. I have been able to manually ground the circuit and verified that the light itself as well as all the wiring is good. The pin for the ses light on the ecm itself doesn't ground under any circumstances either. (Key on or by jumping the diagnostics port.) Taking the cover off the ecm I can't see anything visibly wrong with any of the circuits. I have verified that the ecm is getting good power and ground. I am thinking I have a bad ecm as I should at least be getting a code 12 when in diagnostic mode.

-Here's what's throwing me off. The injectiors are still being commanded to pulse, and I still have spark (albeit pretty weak.) If the Ecm was bad would this still be the Case?

Thanks

 

I replaced the ecm with a reman one, and the check engine light now functions. I was also able to get the car running, though the check engine light is on as well while running. My problem now is that I cannot pull codes by shorting the pins together on the obd1 port. I have 5 volts present and a good ground on the pins however nothing I do will get it to go into diagnostic mode. Is this potentially a faulty reman ecm or prom? Or is it that the car for some reason won't let me pull codes without a scan tool?

 

Cardone ?

 

No It was a blue streak.

 

Those generally seem to be good ecms . But with nil not working seems like it’s bad .

 

Okay, thank you for your input