GM ECM faults help
Thread Starter
Staging Lane
Joined: Jul 2015
Posts: 82
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GM ECM faults help I'm running out of ideas with issue on LS3 ECM faults. Engine uses GM E67 ECM which ran great until one day when it suddenly struggled to stay running and several DTCs appeared.
the DTCs relate to different sensors and power issues and sometimes different DTs appear but all sensors test good and I performed all normal testing for volt drops and clean grounds at ECM under load and while cranking.
here's what puzzles me..... during testing I installed a test wire into unused 5v referene wire pin on ECM to monitor while loading different circuits...... I inadvertently let this wire touch ground with ECM powered and the ECM acted like the key was cycled by cycling the fuel pump on for 4 seconds (this is how it's programmed and normal on key turning on).
grounding any ref wire should not do this and there's obviously issue with ECM not being able to handle the grounding of a ref wire. I have 3 other ECMs and all do the same when hooked up. ECM is getting bad power or weak ground somewhere but can't find it using normal techniques.
I have never seen issue of grounded fault causing the ECM to think it thinks the key was cycled in/off. DTCs relate to CKP, MAP, ECT mostly, sometimes others may show up but don't think they are real faults other than symptoms of a ECM with bad power.
Hoping for some insight before diving into tearing harness apart.
the DTCs relate to different sensors and power issues and sometimes different DTs appear but all sensors test good and I performed all normal testing for volt drops and clean grounds at ECM under load and while cranking.
here's what puzzles me..... during testing I installed a test wire into unused 5v referene wire pin on ECM to monitor while loading different circuits...... I inadvertently let this wire touch ground with ECM powered and the ECM acted like the key was cycled by cycling the fuel pump on for 4 seconds (this is how it's programmed and normal on key turning on).
grounding any ref wire should not do this and there's obviously issue with ECM not being able to handle the grounding of a ref wire. I have 3 other ECMs and all do the same when hooked up. ECM is getting bad power or weak ground somewhere but can't find it using normal techniques.
I have never seen issue of grounded fault causing the ECM to think it thinks the key was cycled in/off. DTCs relate to CKP, MAP, ECT mostly, sometimes others may show up but don't think they are real faults other than symptoms of a ECM with bad power.
Hoping for some insight before diving into tearing harness apart.
