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Discussion Starter #1
A while back I had a parasitic draw. Took a couple of years to diagnose and repair; I don't drive the car much and it sits in the warehouse. Ended up replacing the BCM. What was happening is that periodically, the car's battery would be dead. Periodically, I did catch the car while it was drawing down the battery; all the dash lights and exterior lights would come on and a loud electronic hum would occur with static and popping noises in the speakers.

Recently, the air bag light came on when car was started and running; stayed lit while driving. Sometimes it wouldn't light.

The other day, the service engine light came on and the car's engine had a miss.

Last night, I began to pull the codes and while doing so the large electric draw began and the popping and humming noises again were noticed thru the speakers.
This continued even when I turned the ignition off and pulled out the key.

Would this be indicative of a bad BCM? I replaced it a year ago January and doubt I've put 200 miles on the car since...
 

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98 DeVille, 97 DeVille d'Elegance
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I doubt bcm crapped out. If the car sits for extended periods the battery will go dead. Mine takes 3 to 4 weeks and dead.
When the voltage drops to a certain point all kinds of weird stuff happens. Trunk will pop, noises in speakers(crackling/snapping). I would start by charging and having battery load tested and go from there. Pull codes and see whats up(i would clear them as when battery(low voltage situation) a ton of codes get set and muddy the waters.
 

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Discussion Starter #3
Battery was freshly charged. Car has been started and running. It was when I pulled the codes (with key "on" but engine not started) that the same issue I had with the previous BCM exhibited itself and drained the battery before my eyes. I couldn't stop the drain until I disconnected the battery.

I understand what you are saying but that battery wasn't low until the high draw began and completely drained it within 30 seconds. Almost like a bad short that doesn't blow a breaker or fuse. I was waiting for the car to catch fire!
 

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I cant image a draw that high killing battery that quick but not saying didn't happen. Did you put a load test on battery?
Short of the lights the AMP would be only really high draw item I can remember and they are known for causing high draw problems with car off. Might pull the AMP fuse and try again.
 

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Discussion Starter #5
I will do that. When trying to figure out the original problem I would pull the amp fuse to be able to maintain the battery. I would be able to start, drive and allow the car to sit for long periods of time with the amp fuse pulled. I did on long trips plug in the amp fuse so I would be able to listen to music but would unplug when I got to my destination. I kept thinking it might have been the amp but somehow we zeroed in on this BCM. Worked for just over a year...now this...
 
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