Have an aftermarket head unit installed, I'm trying to track down a static hiss/alternator whine combination. I've drilled a new ground on the frame behind the radio for the head unit, no change. I've pulled down the stock pioneer amplifier and cut the ground to it and ran it to the head unit ground, saw no difference. It hisses from all speakers when the car is turned off, and when the car is running there is an alternator whine. Tried moving the head unit ground around the cabin and no ground points fix the problem. Pretty stumped, I don't think it's my head unit because it worked perfectly in my old vehicle, maybe the stock amplifier is toast? Don't have an aftermarket amplifier so that could rule out some things.

Any pointers are appreciated!

 

Probably ur hu to be honest. Is it a pioneer by chance?

Also if i remember correctly the metal behind the hu isnt connected to the car all that great so that may not be the best fix. But its been years so i could be wrong

 

It's a no brand android unit, wasn't that cheap but I guess that's probably my problem. Pretty weird that it worked good in my old car, maybe the stock amp pulls too much power or something

 

what kind of wiring harness/connection did you use for the install. One thing you can try is use the normal ground for the HU and route the amp ground to the same connection.

 

I have the scoche one with the box to retain blinker noises, not sure the exact model. I'll give your suggestion a go and see what happens. I saw elsewhere that one of the speaker wires grounding out could cause this? Could be a lot of working trying to track it down...

 

I've never seen that. if the speaker wire is grounding out then in my experience whatever is providing the power at the break ends up frying (amp or HU)

The most common issues I've seen are either the HU ground isnt great and the impedance between the HU and the amp is off causing the loop. So if you do the suggestion that should hit both issues (although its possible the stock ground connection is poor or connection at the harness is poor). The 3rd most common thing is unique to pioneers but I've seen a tiny subset of units do it as well. but basically if you ground the RCA cable of the HU to the chassis of the HU that fixes that one. But you'd have to be using RCA out from the HU to the wiring harness (that's why i was asking which one to see whether or not you could try that fix) since you have a no brand unit its possible they ripped off their tech or schematic from pioneer.

 

No luck routing the pioneer amp through the head unit harness ground, I bought a pair of inline noise filters and I'm going to try putting them on the power wires for the head unit, see if that makes a difference. If there's no improvement, I guess ill just have to live with it until I get a new head unit. Thanks for your help!