Amp ground affecting tail lights????

[goose5741 10+ year member]

So I thought that my back middle taillight was just out (the one thats above the trunk, inside the car against the back windshield)...but my friend told me (he was behind me yesterday at a light....) that everytime my bass hits it flickers on and makes wierd desins and lights halfway up and weird stuff. This never happened before i hooked my system up...my amp is grounded to the top of the inside of my trunk, could that be messing with the taillight???? I guess i will unhook the amp and see what happens...anyone know what this could be?

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[.::DuD3::. 10+ year member]

thats weird, maybe try grounding your amp somewhere else?

 

[helotaxi 5,000+ posts]

It is possible that a shared ground path could cause the problem. The ground isn't a return path as most people think. It is the supply, electrons are negatively charged and it is the flow of electrons that is measured as current. Using a chassis ground, the electrons will take the path of least resistance through the car body. If you were able to see the current flow through the sheetmetal it would more resemble a river delta than anything else. There would be areas of high flow surounded by areas of near zero flow. If your taillight and your amp are feeding off the same branch of flow, it is entirely possible that the amp is tapping the flow and leaving the light with nothing to work with.

I'm assuming that you have LED taillights? The patterns you describe would be what the controller board of the LEDs does when it doesn't have enough voltage/current to work with.

Grounding the amp somewhere else will probably fix the problem.

 

[pd298 10+ year member]

It could just be plain ole dimming. My headlights dim horribly when my subs hit. The cause for this is having a weak electrical system with a powerful amp. It drains your electrical system of current.