OK, need some help with this. Up until 2 days ago I never had any issues with my audio system. I have a '10 GT, AT with Bose navi. Audio came on when I started the car and stayed on until I got to work 45 min. later. Got in the car to start it up an hour later, head unit on and perfectly working but no sound to speakers. No popping from speakers either. Sound does not work the rest of the day. Park my car in the garage when I get home. I always hook my battery up to a battery maintainer because 1) there may be something drawing power when the car is off, 2) I think my alternator may be gong as the charge is never at it's peak when I hook the battery up anymore after it has been running, 3) my wife makes me do it. I don't know if that has anything to do with anything. Same thing happened yesterday, worked fine in the morning, no sound when I got in it 4 hours later or the rest of the day. Today same thing, morning worked fine, but no sound 4 hours later or the rest of the day. Got home and hooked battery up. i was curious and checked later if the sound would come on after being hooked up for an hour and it did! So now I have no idea what is going on. Any ideas?

 

Since the radio works after the car has been on the charger but not after the car sits for 4 hours not connected to the charger your problem maybe related to your alternator not charging up the battery fully. Your radio maybe sensitive to the battery voltage level. Since you stated that something might be drawing down the battery with the car turned off the battery voltage might drop enough to cause the radio to malfunction. Use a voltmeter and check the battery voltage with the radio working and then check the battery voltage with the radio not working. See if there is a big difference.

 

If your battery isn't full after driving, that's a pretty good sign that the alt isn't charging it well. Either the alt itself or the voltage regulator. Maaaybe the battery, get it tested just in case.

 

Loose battery clamps, I guarantee.....