Weird Audio Issue

[gerahead]

I am dealing with a really unusual issue and I thought that I would see if anyone out there has any suggestions. The project is a 2006 convertible with a 4.0L and automatic transmission. The foremost consideration is that this car has been flooded. We have taken care of all of the known issues so far, except for this one. I noticed early on that every time the battery was reconnected, there was a loud "thump" that was broadcast through the radio speakers. This occurred with the radio (6 disc CD, AM/FM, 2 speakers each door and one each in rear interior quarter panels). That by itself is something I have never seen before. We sourced a "new" used radio head unit that appears to be fully functional. Here's where it gets crazy. When the radio is turned off or the ignition is turned off with the radio on, there is a loud, high pitched squeal (think household burglar alram) emitted from the speakers. If you turn off the radio, the squeal persists, if you turn off the ignition key it persists, if you remove the ignition key it persists. The only thing we have found that shuts it off once it starts, is to turn the key off, restart the engine and then turn the ignition off. We have very limited access to wiring schematics so that is an issue to factor into the solution. If you have any ideas, I am all ears! Thanks in advance for any help you may be able to provide!

Jim

 

[Whpony96]

Replace the 2 amplifiers under the drivers side dash on the left hand side above the hood release. If the car was flooded these are NOT water proof and that is your issue. These have also been known to fail under normal circumstances and cause excessive battery draw in a key-off scenario.

 

[gerahead]

Whpony96,
Thank you so much for this information. I had no idea that there were separate amplifiers. I also managed to find better schematics than I had earlier. The amps both have "hot all the time" power, so it helps explain why we were getting an audible thump with no head unit installed. Your help is greatly appreciated!!!

Jim

 

[DieHarder]

An online manual for our cars: https://iihs.net/fsm/?d=0

 

[gerahead]

DieHarder, thanks for this link. I had found this earlier and was a big help to some of the work that we got finished. While helpful, they are incomplete. For instance, the schematics for the audio system don't include the amplifiers for the subwoofers. There were a couple of other areas where a portion of the circuit wasn't shown.

 

[DieHarder]

Yeah, you're right. There are 4 pages in the wiring diagrams manual for the audio system. Seems like this online version is primarily advertising now. Understand the need to support but it should be complete.

 

[gerahead]

Replace the 2 amplifiers under the drivers side dash on the left hand side above the hood release. If the car was flooded these are NOT water proof and that is your issue. These have also been known to fail under normal circumstances and cause excessive battery draw in a key-off scenario.

That was it! Disconnecting the amps solved both the "thump" on battery connect and the screech when the radio was turned off. Now all is well! Thanks again!