Pioneer AVH-2700BS RCA Problem

I installed an amp to power my door and deck speakers but one single channel (RF) makes all kinds of static noise. I know it is the radio, I have swapped the hu for an older one I had and the sound is amazing but I really want this deck back in. I tried wrapping ground wire around the plug and attaching to the case but no joy, still noisy. I'm not afraid to open it up and solder connections if needed but I haven't found any information about single channel static only all channel static so I don't know where to go next. Please help

pioneers had pico fuses in them at one time and if they were bad you got terrible sound out of the rcas. What they look like and where they are i don't have a clue or how to repair them. All stuff like that gets sent to our repair facility. this might help- https://www.diymobileaudio.com/threads/understanding-the-pico-fuse-and-rca-connections.144340/33 years as a installer now just a retired old guy. Favorite thing to install/topic are remote starts/car alarms. Stop using test lights!!!