My JBL / NAV sound system has a strange and very intermittent problem -- it happened last summer several times when the weather was hot (a/c or not), and only happened a couple of times in the winter when the wife was gone and the volume was crankin'.

Without warning one of the channels emits a loud "Whoop" sound (almost like feedback) for about a second, then that channel emits a low-level rumble until the car is turned off and back on. It has done this intermittently on radio, CD, and later when I added factory XM it did it on that too.

I'm thinking that the JBL audio amplifier has a thermal runaway issue, but there is no TSB on this and no trouble codes stored.

Since the dealer "could not duplicate" I'm wondering if this is a really rare issue or if I should lobby harder for the under-seat amplifier to be replaced.

Anybody else have this problem?