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  #1  
Old 11-02-2010, 10:40 PM
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Default Battery drains over night

I am new to this sight. I own a 2001 Blazer 4x4 that has a 1amp draw on the battery. I have electrical experience and located the draw coming form the TBC fuse. The factory manual shows this fuse feeds the keyless entry module, the flash to pass switch and the body control module. When I disconnected the brown connector(power to the BCM) the drain goes away. I also have disconnected the door switch so it doesn't interfer with my troubleshooting, but my question is how do I further track down this problem. Thanks
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Old 11-03-2010, 06:51 PM
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Does the draw stay at 1A consistently even after waiting a minute or so?

If it goes away when disconnecting the BCM, something is either keeping the BCM active or the BCM is bad.
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Old 11-03-2010, 10:11 PM
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The current draw will drop to .370 amp after a minute and will completely go away if I disconnect the brown plug on the BCM. I have metered the power wire on C1 pin A2 to ground with the TBC fuse pulled and that circuit is not shorted to ground. I also metered C1 pin A2 on the BCM and it also is not shorted to ground. Thanks for your input
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Old 11-07-2010, 09:27 AM
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I have a '02 Trailblazer and am experiancing the same, except my draw is about 1.5A and it doesn't reduce. I haven't tried disconnecting the brown plug on the BCM but will. Reading around in other forums, I'm thinking my problem is that the BCM is not going to sleep. I suspect replacing the BCM is a dealer only job because of reprogramming, but I'm looking around to see if that's the case. Does anyone know?
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Old 11-07-2010, 01:39 PM
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The BCM will indeed need to be programmed for your truck.
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Old 11-12-2010, 02:48 PM
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Quote:
Originally Posted by Bigbser View Post
I have a '02 Trailblazer and am experiancing the same, except my draw is about 1.5A and it doesn't reduce. I haven't tried disconnecting the brown plug on the BCM but will. Reading around in other forums, I'm thinking my problem is that the BCM is not going to sleep. I suspect replacing the BCM is a dealer only job because of reprogramming, but I'm looking around to see if that's the case. Does anyone know?
You first need to figure out which circuit is giving you this current draw by pulling fuses one at a time. Then you can trouble shoot that cicuit. I would start under the hood because they are the main fuses. Replacing the BCM is very expensive and might not solve your problem.

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Old 11-12-2010, 02:59 PM
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Back to your problem '01 blazer', 0.37A is still way too high. If it doesn't drop to below 0.035A (35mA) after 10-20 minutes with all of the doors closed, etc, then there is definitely something keeping the BCM active. It could be anything on the serial bus network which will be incredibly difficult to diagnose.
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Old 11-13-2010, 06:22 AM
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I appoligize for hijacking 01 blazer's post but wanted to give an update to my 02 Trailblazer's power draw. My problem was in fact the BCM. After two days, the dealership mechanic was also reluctant to make that determination, he was very open with me about what he was doing. He finally decided to replace the BCM and $423 later, problem solved.

Just wanted to thank the members and administrators of this forum. As a pretty competent shade tree mechanic, electrical problems in these late model cars can still be quite difficult to track down. During my search for my problem I picked up some other tidbits of info to help me with other situations. Thanks a bunch.

Good luck 01 blazer with your problem. I'll be interested to hear what fixes your problem.
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Old 11-27-2010, 06:26 PM
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Thanks 'swartlkk' for your replay. Since then I have replaced the battery because it wouldn't hold a charge for any length of time. At first I could leave it over night and it would start in the morning, then it got to the point of not starting after sitting for a couple of hours. Today I checked the current draw again and after a minute it dropped to .370 amp. I left it hooked up for 20 minutes and it dropped to 16 milli amp. From what you recomended it should be ok. It seems that I got on a rabbit trail with this one. Thanks again for your help it was greatly appreciated.
  #10  
Old 11-27-2010, 06:43 PM
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16mA is right where it should be after everything goes to sleep. Do you perhaps have an overcharging issue that is cooking the battery?
Old 11-27-2010, 06:43 PM
 
 
 
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146, 2001, 98, battery, bcm, blazer, charging, current, draining, drains, draw, overnight, tahoe, tbc, trailblazer, volts


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