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?

TCHconn — Have you looked at the AV system's own trouble code readouts? They are separate from those of the car. I'm attaching three sets of Repair Manual pages that address how to do this, how to interpret the results, and how to remove/install the amplifier (there's no need to remove the passenger's seat to do this).

Stan

Attached Images

	AV-019to026.pdf (262.1 KB, 17 views)
	AV-027to029.pdf (27.4 KB, 12 views)
	AV-139to142.pdf (379.8 KB, 10 views)

Thanks for this. Although I haven't been successful creating the 5.1 / 6.1 disc, I do have the service manual CD-ROM and have "navigated" around the NAV / Radio service screens -- and there aren't any codes in the radio system before or after this happens.

It sounds like an amplifer breaking into oscillation -- if it were the data bus I suspect it would have more severe sound like a noise burst at full volume... THAT would capture a code for sure. Alas, analog stuff hardly gets captured as a fault in modern systems.

Thanks again for pulling the docs. Now that the console-squeak TSB has been published, the car is going in to the dealer for a visit -- maybe it will act up while under scrutiny.

TCHconn — You might try unplugging and replugging the three connectors at the amplifier — perhaps there's a loose/bad connection. This is easy to do (the black plastic cover is held on by two plastic clips — pull them straight up to remove). This will generate error codes, of course, which you can clear. Make sure that the ground lead is tight too. (Of course, a bad connection might be at the radio end of the harness!) Otherwise, perhaps it's an internal amplifier fault, as you suspect.

Stan