Car Stereos: Security with cd player, vehicle security system, gm radios

Question
I have a 2000 Chevy Tahoe, and installed it. Everything works great until I shut the truck off and lock it.  I get back in, the cd player powers up just fine, everything works, but there is no sound.. I know it has to do with the security feature on the truck. If I close the door, lock it to activate security, unlock it, get in it, start it, then it works fine. After I turn it off, it does the same thing.  Kinda annoying.. Can you help me bypass the security??  And How?  Thanks a million, Scott

Answer
Hi Scott,

I'm very doubtful that the radio problem you're having has anything to do with the factory security system.  I've never seen any GM radio that was tied into the vehicle security system in any way.  GM radios have a built-in security system called Theftlock, but it's completely internal; and if the Theftlock system was active you wouldn't be able to power up or control the radio at all.

My guess is that you have an intermittent problem either with the factory amplifier, or a speaker.  If your Tahoe was originally equipped with a Bose system, or with Onstar, then there's a built-in factory amplifier located behind the glove box.  If the amplifier isn't working correctly, that would explain why you have no sound even though the radio appears to be operating properly.

Another possibility is that there's a shorted speaker wire, or a defective speaker, that's causing the factory amp or internal radio amplifier to shut down for protection.  

If I had the truck for troubleshooting, I'd probably use a multimeter to check for AC voltage on the audio input wires to the amplifier, as well as the output wires; and to check the power connections at the amplifier itself.  This isn't an issue I've heard of before, but I'm confident that if I had some time to work on it, I could at least track down the source of the problem.  

Again, I don't think the problem is related to factory security in any way.  You might try just switching the key on and off, or opening and closing the door, to see if that has any effect without using the lock system.

Good luck!

Brian