Having problems fixing this nasty and annoying interference/ground loop or ground problem. It can not be re-created it is totally random. The only thing I've noticed is that it tends to only happen if volume has been above 25-30 but not every time. I've checked all my head unit connections multiple times and made sure they are SOLID (they are scotch locked).
RCA's are cheaper scosche and stinger but have never given me problems in 4+ vehicles. They are no where near my power or ground. Connections at head unit are electrical taped to prevent rubbing against each other. Amps are grounded at the rear inner-fender (uni-body so there is no "frame") with less than 3' of cable each.
Head unit ground is into stock harness with the aftermarket harness. Every time I park and pull out my dash to see if I can get it to stop it seems like anytime I touch the ground wire it stops momentarily but eventually comes back on.
If I turn the car off and go into work for a few hours with it still doing the annoying noise when I come back out it will have stopped without changing ANYTHING! At this point I am clueless and have narrowed it down to four options:
1. Bad head unit (PICO Fuse)
2. Bad aftermarket harness.
3. Bad head unit ground.
4. Bad RCA's
I don't have a spare head unit besides stock or extra wire/RCA's so I'm stuck on how to find out what's wrong here.