Car Stereos: infinity gold stereo, jeep grand cherokee, infinity gold

Question
I recently bought a 99 Jeep Grand Cherokee. For the first couple of hours the stereo sounded great. Then I heard a pop noise and only my small speaker on the left side of the dash works. A little while later i pushed my automatic lock button on the driver side door and the stereo came back on for a few minutes then went back out. If I keep pushing the lock button it will come back on briefly but go right back out. Sometimes it will stay on for 10 minutes but sometimes only for 1 second. Do you know what my problem may be? And what does my lock button have to do with the stereo?

Answer
Hi,

Sorry about the delay in answering your question.

The fact is, I've never run into a problem like the one you're describing, and I really couldn't say what's causing it.  

The Infinity Gold sound system uses a 6-channel factory amplifier, located (and easily accessible) under the rear seat.  It's almost certain that the problem originates with the factory amp, but it's not clear why it's being affected by the door locks.  If I were troubleshooting the problem, I'd unplug the factory amplifier, and use a multimeter to test each of the speaker wires in the amp plug to see if a wire is being shorted or grounded when the door locks are operating.  There is a possibility that you have worn or broken wires in a conduit running into one of the doors, and a speaker wire may be making contact with a door lock motor wire.  Potentially, this could shut down the amplifier, but it's not a very likely scenario.  

If it's simply a defective amplifier, it's very easy to replace if you can find a replacement.  OEM amplifiers are often found on eBay.  Otherwise, it's possible to bypass the factory amp and run four speakers directly from the stock head unit; however, I'd recommend upgrading the front door speakers if you do this, because you won't be able to retain the factory dash tweeters, and the stock door speakers aren't made to play the full audio range.

Hope this helps!

Brian