CTA4AVANT

My rear door speakers on my Avant have been cutting in and out recently. Any recommendations on how to track this problem down?

I have a Sony HU and a Sony Amp. I did not do the install myself.

Thanks.

MacSub

Are the rears running off the Sony amp or the feeble Audi OEM amp?
Could be the amp, are the fronts running off the amp as well or direct off the head unit?
I'd temporarily run some speaker cable from the HU to the rear speakers and see if that cures the problem. If it doesn't then it's a head unit problem, if it does then it's the amp, or a loose connection from amp to speakers or faulty RCA cable to the amp. If the problem effects both left and right rears at the same time then it's more likely to be the amp (rather than cabling or faulty speakers).

CTA4AVANT

Looks like I'll have to pull the door panel for a looksie.

MacSub

swap the rear RCA leads over on the amp (left & right) and see if the problem switches to the right rear speaker. If it does then it's not the speaker or connections and must be the amp, RCA or pre-out on the head unit.
If the problem stays with the left rear then it's not he amp or head unit so you'll need to check the speaker connection at the amp, then lastly take the door panel off and check the connections at the speaker. If everything still looks OK check the speaker itself, take it out and stick it on your home hifi to ensure it is working.