1997 cavalier. The alternator is making a high pitch electrical sound (you have to put you ear up to it to hear it) after the engine is turned off. After pulling the relays, breakers, and fuses, it stoped when the PCM fuse was pulled. The 4.96 volts at the alt plug stoped also. I put the fuse back in and 0.0 volts and no sound. Restart the engine, the alt charges. Shut it off, and the sound is there, unplug the alt plug and have 4.96 volts. This is also draining the battary. What cha think?

 

did you ever figure out what it took to fix it i am having the exact same issue i was told to replace the pcm?

 

Has anyone figured this out? I'm having the same issue with a no start thats flooding the plugs and backfiring through the throttle body. The mechanical timing is correct the compression is correct the control module is good the crank sensor is good the map sensor is good I mean I have gone through this car and cannot figure it out. Any help at all would be greatly appreciated

 

I had this problem on my 97 Chevy Cavy RS, and it seemed to be tied into my Ignition Coil Packs, I ended up having a bad one, lol.

 

Thanks for the reply, I have also changed the coil packs with known good ones I had laying around. I'm down to the computer screwing with the timing I have checked absolutely everything else.