1999 S80 Radio short circuit problem

[andrew79]

All of a sudden my radio/stereo system started to emit a very loud buzz--more like a roar. I could not stop the buzz unless I turned off the radio and then turned off the ignition. The radio did not go off when I turned it off, but this was still necessary to get it to turn off with the ignition. The buzz goes away when I start the car up--occasionally--but then returns when I slam or even touch the handle for the passenger door. It seems to be activated by bumps as well. I took the passenger door panel off and checked all the plugs, as well as the plugs into the radio unit (HU801). I also replaced the amp and made sure the plugs were clean. I pulled fuse which control the door modules but to no avail. At this point I am not sure what to do next, so any thoughts and advice is most welcome. Andrew in CA

[SuperHerman]

Pull the radio fuse and see what happens. You need to isolate the feedback. If it stops then look at all the radio wires for shorts. Easiest thing is to take a meter to each wire and look for a short. Or start by looking for frayed wires where they go from the body to the door to the speaker. Hopefully you have a simple short causing the feedback. That is where I would start.

[draser]

It sounds like a loose ground, check radio ground wires against a schematic. Make sure ground lugs are clean and tight, location should be in schematics.