HU chassis to car chassis resistance

[Spike243 10+ year member]

I've been having an annoying issue with ground loops recently. When the car is off there is no noise but when I start it there is immediate alternator whine so I know I have a ground loop issue. I have tried direct battery ground, grounding to the amp ground, re-routing rcas, and unplugging the rcas from the amp. Unplugging the rcas causes the noise to go away right away. So I began to ohm my grounds and I found that there is about 16ohms of resistance between my head units chassis and the car chassis. Is this my issue? Rca's all have perfect continuity to the HU chassis.

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[fasfocus00 5,000+ posts]

what speakers do you have? have you tried to isolate the ground loop to a single channel? have you tried grounding the RCAs?

 

[Spike243 10+ year member]

I have some pioneer coaxials. The sound seems to come from both channels even with an rca swap. I haven't tried the rca grounding but I was wondering about that when I saw a 16 ohm resistance between the rca negative/HU chassis and the car chassis

 

[Spike243 10+ year member]

any other input on this?