Alternator Grounding problem

[joelsr]

2001 2500HD D/A. Had to have the original factory audio head changed to an aftermarket unit. This required a separate box for the OnStar. Since installation the left speaker would fade out when the truck was running but no problem in the access. position. I was told that GM has a lousy grounding system and the problem is due to AC bleedthroug from the alt. This linda makes sense because the only time there is a problem is when the truck is running. Incidentally, this problem is intermittent, and seems to occur when the meter is reading in the 15 range. When at 14 or so the left speaker kicks back in. In any event it was recommended that I run an additional #4 or 6 grounding strap from the alt. to the chassis. Anyone have any comments. Thanks in advance.
Joe :mad:

[More Power]

Since the alternator is bolted onto the engine, I doubt it has a grounding problem. If there is a ground issue, it would more likely be a frame to engine or engine to cab ground.

Try connecting a good temporary ground strap from the engine to the frame and engine to cab, then try to duplicate the problem you're seeing with the audio.

MP