Causes of alternator whine?

[Supergumby5000 5,000+ posts]

This ones kind of a mystery to me, help me solve it.

I think i have a bit of alternator whine. Not much at all, but i think im going to troubleshoot it just to see if i can get rid of it. Heck, it may just be the mechanical sound of the alty, but i wanna check.

Anyways, what are the causes of alternator whine? Obviously a bad ground will do it, but i dont think thats the case in my truck.

All my connections are battery-to-battery, the RCA's are grounded on my HU (i had speaker whine, fixed it).

Could stock wiring be the cause of it? Or could the blown pico fuse in my headunit be causing it as well, even though my RCA's are grounded and the speaker whien is gone?

The only other thing i coudl think of that would be causing it is i added two grounds to my alternator: a bigger ground while doing the big 3, and i also grounded it to the frame. I havent had a chance to crawl under my truck yet, but im thinking maybe the ground on the frame got corroded?

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[NeverEnuffBass 10+ year member]

running speaker wires across or with power, using the factory radio ground (esp in GM trucks), speakers grounding out, and a million other things

 

[Supergumby5000 5,000+ posts]

running speaker wires across or with power, using the factory radio ground (esp in GM trucks), speakers grounding out, and a million other things

negative on all of those except factory GM radio ground. I'll swap that this weekend and see if it makes a difference.

 

[NeverEnuffBass 10+ year member]

negative on all of those except factory GM radio ground. I'll swap that this weekend and see if it makes a difference.

I've solved several noise issues in full size GM's like this. First try a new ground, if the noise is still there try grounding with the amps