I've got a 2009 coupe with nav and a bose system. Its got some weird audio issues and I'm looking for some ideas on troubleshooting my audio system. My left front door speaker randomly doesn't work some times for several minutes and I don't have a route in the gps. The right front door speaker is garbled sounding all the time. The right side wall speaker that's next to the rear seat passengers leg cuts in and out for a few seconds intermittently as well. Wiring issues, bad amp? I'm almost guessing the garbled speaker might be bad but the others sound like connection issues.

 

Here is the link in the FSM

Factory Service Manuals - NICO Club

Could be a poor ground or connection in the wiring harness?
Was this vehicle ever involved in a flood?

Telcoman

 

Think I found the problem. PO had spliced into the wire harness near the amp in the trunk. Lots of improperly crimped low quality walmart grade butt splices.

 

I have no bass nor rear sound on a 2013 g37 vert. I hope some of the recommendations work. Thanks.