2006 Sierra 2500hd 55k mi.
Engine won't start. Turning key to "on" position brings up instrumentation lights and gages. Turning key then to "start" all instrumentation power drops, no cranking, no clicking, no sounds what so ever. Releasing key back to "on" instrumentation lights come back a couple of indicators stay on usually the security icon and a check 4 wheel drive message but not always. The power door locks stop working, remote key stops but the headlights, interior lights, radio, AC etc still work.
It seems like a very faint high pitch whining is coming from or around the alternator. If I pull and reset the PCM fuse the whine stops the dash warning lights go out and all the power locks and remote keyless entry system starts working again.
I have swapped out the battery and had the starter tested. Both are fine. It’s seems like definitely an electrical problem to me. My first thought was maybe varmints chewed some wiring but I can’t find any signs of that. Although I can’t see under the fuse box and I really don’t want to take it out!
Do you think it could be a bad PCM/ECU? How can I test it to be sure? What should I look at Next?
Tuesday, March 8th, 2011 AT 7:30 AM