There’s a ton of info regarding the ground loop issue when installing an aftermarket head unit but I can not find a clear answer. It should be a very simple fix if you know what needs to be grounded. Can anyone tell me precisely which ground(s) need to be fixed? Is it the ground at the factory amp?

 

As I understand it, interference occurs when the head unit and the amp do not have the same level of grounding. To avoid this they are often wired to the same ground point. Absent that I would (and have) tried to find very good independent grounds such as scratching off paint of a body piece and attaching it there.

 

when you refer to the ground of the head unit are you saying the black ground wire in the power connection or the speaker grounds at the head unit? I used a Tee tap on the black ground wire on the plug going into the amp and ran a wire to the head unit power adapter plug and tied them together. It didn’t solve the problem. I have to RCA noise filters that eliminate 80+% of the noise but if I remove them I still have a lot of noise which tells me I haven’t identified the proper grounding scenario. It seems simple if I knew where the culprit was. I notice I got a lot more noise when the RCA filters are pushed into the rack and are near the aluminum racks/bracing behind the dash however with everything pulled out dangling in front the of the dash there’s almost zero noise.

 

Power ground, not speakers. Good grounds are one of the keys.