Strange issue with intermittant Temp Sensor Signal, E40 PCM in 2006 GTO(replaced ECM)
Back story - I have been having an intermittent temp sensor signal issue that a reflash of the ECM will fix temporarily. When the signal fails, my gauge drops to cold and fans quit working. I'm not sure now this is related, but the A/C quits working in the car as well. When this issue is present, I can scan these signals and all seems to be operating as normal, according to what I'm seeing in the scanner. Even though the gauge shows cold, ECM sees temp as normal and I can also turn on/off the AC, Engine fans etc via the "Vehicle Controls" console in VCM scanner.
Current Status - Since I found this issue I took a semi educated guess and was convinced it was in the ECM, reason being...I could do a reflash and all would work fine for a random amount of time. I could be driving down the road just 15 miles after a reflash and it would fail, or it may take several days and hundreds of miles. No rhyme or reason that I could pinpoint. With that said, I replaced with a NEW ECU a week ago and thought it was fixed only to find out yesterday that this is not the case as my temp gauge dropped to Cold again on the way home from work, engine fans shut off and A/C quit working. I didn't have my laptop on me but was fairly close to the house and once I got home, relfashed and all is good again (for now)
Which way do I go now? Is it possible that its the BCM or even PIM? if so, why does a reflash of the ECU temporarily fix it? I cant imagine this the case but Is there any chance at all that my MPVI Pro unit is leaning towards flaking out? I paid to upgrade it a couple weeks ago but held off since this issue started because now that my wife is working, the Goat has become my daily and so I keep my MPVI in the car in the event I need to perform a reflash.
Thanks in advance for any input
-Steve
Next time this happens, I'm going to try a battery disconnect. Wont fix it but may tell me a little more about what is temporarily fixing the problem. I'm also working on sourcing schematics to help troubleshoot but I cant imagine the problem being external to a controller.