Problem with speakers. Audi a6 98.
 

Hi.

I've got an Audi a6 1998.
My problem is that all my rear speakers don't work. I have no problem with the front speakers. It's not an original player, but some Pioneer player. The problem started shortly after I installed it. I have tried to replace some of the cables behind the cd player, but that didn't help.

My question is, what might the problem be, and what should I first check?
I consider changing the wires and/or the speakers itself, but I hope theres a simpler fix possible.

Does it excists any drawings of the wiring system, and how to change both the wiring and speakers? In that case, where??

:)