the sound system in my C4 isn't working. I turn it on and all it does is make weird squealing noises. all the lights on the head unit work as well as the clock and the antenna go's up but will not go down.
I'd like to upgrade the head unit to a touch screen DVD unit, I found what I want on crutchfield.com and the wiring adapter kit but how do I know if the Bose speakers/amps are good? I don't want to buy all this stuff just to find out that it's the bose amps that are bad.

 

I don't have the Bose Radio or amp in mine so I can't answer that but it might have something in the FSM that could explain how to check it out.

Good luck

 

The squealing noise does sound like your amps. There are articles on the net on how to change out the electrolytic capacitors on the amp board. I have done this after the squeal and it fixed the problem. I also changed out the radio.
I installed a special interface between the radio and the amps. It allowed me to set the volume level correctly.