Electrical/Computer Problems
 

Hello I am new to this forum and have an annoying problem. I have a 2001 MC SS with 127000mi. I am the only owner and have maintained the car well. Up to this point of its life, I have had very little problems with the car. Last summer the factory amplifier mounted under the rear deck in the trunk died. I replaced the amp with an after market amp and upgraded the speakers using all the required hardware needed continue to use the factory radio head and wiring harness. Everything worked fine. During the last months, I noticed battery draw down and a couple of times the security light would randomly come on. (I didn't experience the normal security light problems listed in other posts) I figured it was a battery issue and replaced my 4 year old battery. This rectified the situation for a couple days. I started experiencing battery draw down again and then had the electrical system tested. Battery, alternator and starter all passed the diagnostic tests. Shortly after this the random accessory relay located in the driverside fuse panel started clicking. Thinking it was a bad relay I replaced it. Same thing happened. This seemed to be more frequent when the weather was hot and humid. I live in SC so it is always hot and humid so as the problem got worse I took it to the shop. At this time the ignition started sticking and I would have to fuss with the key to get the car started. (Not the same issues as the passlock problems) The mechanic said he believed it maybe a BCM problem but it was obvious the ignition had to be replaced and that may fix the problem. I replaced the ignition but the other problems continued. Do these symptoms seem like a BCM problem or are there other trouble areas I should check.

Sorry for such a long post but I wanted to get all the information about my problem out there at once. Any help that you can provide would be greatly appreciated. Thank you in advance!

Colin

What exactly is the car doing? Relay clicking and the battery's just losing power and dying? Check your wiring with that sound system.

If you have a problem with the car starting/staying running though and the car immediately cuts off, it's your crank sensor.

x2

Sounds like something is drawing down your battery when the car's sitting.

I've checked the amplifier and it doesn't seem to be the problem. The clicking is coming through the a relay on the side of the dashboard. When I remove the BCM fuse, the clicking stops and I no longer have battery drain. If I leave the fuse in, the battery will no longer have enough voltage to start the car. I was hoping someone out there had similar problems and can give me an idea that it may be the BCM going bad and how much a new one costs.

The shop definately thinks its a BCM but the car is 10 years old and I already spent 800.00 on the ignition system. My mechanic thinks power is feeding backwards through the BCM, but said its electrical and it may be a combination of computer and circuit issues. Much like the ignition was a starting point but didn't totally fix the problem.

OK, definitely sounds like the BCM is bad. I've heard that this is a common issue on our cars- never seen the issue in person though.

$800 bucks for the ignition?!?! You got shafted.

Same problem, did u get it fixed?
 

I have 03 monte carlo with exact same problems, clicking battery rundownprotection relay. & battery drain. Did u get it fixed. If so please let me know.

When I replaced the BCM, it was fixed. The tech that reprogrammed it said the BCMs have problems in high humidity climates.