mdpierce8 Posted July 22 Report Share Posted July 22 Hello all. I’m having an issue with my GP where it seems to keep resetting the ecm on its own without removing the battery or fuse. I’ll go through what I think is the idle relearn procedure where it starts and runs at like 2k rpms for around 10 mins with the CEL on, then it’ll just die all on its own, then once restarted it runs perfect, idles perfect, CEL is off. But if I shut it off for an extended period of time and restart it it wants to go through the whole idle relearn again. Like the ecm has lost power or ground somehow? I’ve checked around for loose wires and grounds but to no avail. Any insight at all on this would be greatly appreciated! Thank you! Quote Link to comment Share on other sites More sharing options...
Schurkey Posted July 22 Report Share Posted July 22 Obtain the service manual set for your vehicle. Look in the wiring-diagram section, find out how the ECM is powered. Verify that wiring for loose connections, weak fuse-blade terminals, broken/intermittent wires, etc. I would want to connect a scan tool, and see what other info I could get that might be useful. Verify EVERY sensor and computer output. Wouldn't hurt to check the battery connections, too. Assure that the battery isn't losing voltage while parked. mdpierce8 1 Quote Link to comment Share on other sites More sharing options...
mdpierce8 Posted July 22 Author Report Share Posted July 22 10 hours ago, Schurkey said: Obtain the service manual set for your vehicle. Look in the wiring-diagram section, find out how the ECM is powered. Verify that wiring for loose connections, weak fuse-blade terminals, broken/intermittent wires, etc. I would want to connect a scan tool, and see what other info I could get that might be useful. Verify EVERY sensor and computer output. Wouldn't hurt to check the battery connections, too. Assure that the battery isn't losing voltage while parked. I do have a scan tool which is just an aldl usb cable and tunerpro and I can only get it to connect after it finishes the idle relearn. During the idle relearn it won’t connect at all. Quote Link to comment Share on other sites More sharing options...
mdpierce8 Posted July 27 Author Report Share Posted July 27 Everything is checking out so far. Wiring is testing good, good hot-at-all-times voltage to ecm, good grounds; But it did seem like the pins in the connectors to the ECM were bulged out, I'm starting to think the pins in the connectors are the issue. I'm gonna see about depinning the connectors and see if I can reshape them to make good contact on the ECM pins. Quote Link to comment Share on other sites More sharing options...
mdpierce8 Posted August 10 Author Report Share Posted August 10 Well still continuing this project. Starting to wonder if the ecm is the cause now. I did notice that it misfires sometimes only when relearning the idle. I’ve also discovered that a lot of the sensors on this car are faulty. I’ve replaced the TPS (Bosch), IAC (Bosch), MAP (AcDelco), Crankshaft Position Sensor (CarQuest), Oil Pressure Sensor (Delphi), and Coolant Temperature Sensor (carquest). The ECM was also replaced with a 88999195 AcDelco ecm. The owner before me replaced the ignition coils and module and he thought it needed a crankshaft position sensor which the car came with the new carquest one when I bought it. Still getting the same issues though. There’s a small wiring harness that runs from the crank sensor to the ignition block and it is very oily. Wondering what shape those wires are in. It’s the only thing that makes sense to me right now. Quote Link to comment Share on other sites More sharing options...
mdpierce8 Posted August 10 Author Report Share Posted August 10 nope. That harness checked out. I’m at my wits end at this point. Without a back probe kit, I’m not sure there’s much else I can do. I’m suspicious of a sensor being shorted and putting the ecm into limp mode. SES light is on and there’s no communication with the ecm when in this mode with the aldl cable. It misfires only at a specific rpm range between 700-900 rpm. I’ll have to take some time off and think about this for a while because I’m not sure what to do. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.