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Old 03-31-2009, 07:33 PM   #1
thetight
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Default what does a BCM do?

I thought I had a bad turn signal bulb but once I replaced the bulb it didnt fix the problem so I talked to a guy at the dealership(I used to work there in sales) he said I need to replace the BCM. Well it seemed to be expensive for it to repair just a turm signal so I left it be. Now Im starting to have other electrical issues.1 is when I start the car it idles fine but when I start to move it dies just like the service colmn lock issue but no message comes up and I have the bypass. It may take 10 trys to get moving once I get going I can start and stop all day with no issues.Other times it will start up and go with no problems. 2 Now when driving sometimes the dash lights will flicker and once the car died while driving down the road. I checked the battery cables and everything is tight. I'm wondering if the BCM has something to do with this problem??
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Old 03-31-2009, 07:48 PM   #2
Bill Dearborn
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Check the codes on the car using the DIC. That will give you a lot of information and someplace to start from. Turn the ingition to on and then push and hold the options button followed by pushing the fuel button 4 times. The car will then enter diagnostic mode and you can let loose of the options button. The diagnostics will cycle through each subsystem on the car (including the BCM) and show all codes present in each subsystem. A code is an Alhpa character followed by four numerals and possibly followed by an H or C or both the H and C. Report them back here and somebody can help you then.

Bill
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Old 03-31-2009, 07:57 PM   #3
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What type of column lock bypass do you have installed?
Is it the GM Harness K bypass or an aftermarket CLB?
Sounds like the BCM is doing what it is supposed to do, and the bypass relay has failed....

(Just curious, does your column still lock or has the lockplate been removed?)
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Old 03-31-2009, 08:36 PM   #4
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I'm not with the car now so I can't pull codes. It's an aftermarket clb and have never had an issue for going on 3 years now asfar as pull key or any other messages they haven't came across the d I c since having the clb installed
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Old 04-01-2009, 02:32 AM   #5
Bill Curlee
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BCM = Body Control Module It controls or interfaces with ALL the body functions and communicates with ALL the other modules. Without it,,,your car will not function.

Yes,,,,reading the DTCs will help us help you figure out whats going on.

BC
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Old 05-19-2009, 11:23 PM   #6
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Default what does bcm do?

Quote:
Originally Posted by Bill Curlee View Post
BCM = Body Control Module It controls or interfaces with ALL the body functions and communicates with ALL the other modules. Without it,,,your car will not function.

BC
I just saw this thread when trying to find out more info on the bcm. I'm learning all right to the tune of about $1800 from our local Chevy dealer. We had some very heavy rain in a short while. I went to ge the Vette and could not start it. Had some high water but not a flooded car. Battery was drained so had it recharged and tested but by the time I put it back and tried to start the car nothing. Had it load tested again. Bottomline took the charge but didn't hold it for a short while...replaced with new battery...load tested fine....installed tried starting and nothing. I thought perhaps a starter problem or even a coroded cable. All fuse boxes, etc were dry. Did no have a capability at the house to check the module connection on the car so had it carried to the dealer. Found out today it was the bcm...man, not cheap but here's the alternative...had I gotten one from someone other than the dealer they would not stand behind it unless a GM part purchased through them and installed by them. So sucking it up BUT I get my Corvette back running!! As a club member I do get a discount...not a large discount but any savings is savings
Bill

Last edited by majbillgsd; 05-19-2009 at 11:26 PM.
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Old 08-09-2010, 12:22 PM   #7
Arkay
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Default Me too - sick BCM

Like some of the others.... after two dead batteries on my 2001 Coupe it was taken to the dealer on a flat bed truck. The BCM is drawing 4 amp and that is what is killing the batteries. The big unknown at the dealership is understand what circuit is shorted. Just replacing the expensive
(heard $1,000) BCM may not fix the problem. They are trying to find the bad circuit and this could be as expensive as the BCM.

This is not going to be an easy repair

Last edited by Arkay; 08-09-2010 at 12:28 PM.
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Old 08-09-2010, 01:55 PM   #8
Bill Curlee
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Dick

Im 99.1% that your BCM is NOT bad.

4 amp draw is NOT a short. When you say short, think of fire flames, burnt wires and components and smoke.

You just have something that is staying ON that should be OFF. If your STEALERSHIP cant find the issue in an hour,,,find a better service center!

Please call me. PM SENT. I hate stupid service centers!

NOTE! I tried to PM you but, theres not a PM available in your profile. I did leave something. It might be in your IMs


Bill C

Last edited by Bill Curlee; 08-09-2010 at 02:06 PM.
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Old 08-10-2010, 04:25 PM   #9
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Quote:
Originally Posted by Bill Curlee View Post
Dick

Im 99.1% that your BCM is NOT bad.

Bill C
On Monday the dealership called saying it could be the $1,000 BCM (Body Control Module) because the vehicle was drawing 6 amps with the key OFF. The tech was trying to find the short or whatever that killed two batteries. He was having to do it the old fashion way, one circuit at a time. The service writer called back at the end of the day saying the new battery was okay that it charged fine and the tech found the interior lamp ON so he turned it OFF. The excessive current draw stopped but he wanted to let it sleep over night in his stall and check it in the morning. They called Tuesday and I have the car back. For only $114 we went from Intensive Care to Release.

I have no idea how the interior lamps got turned ON but it was dying on me during the day and I probably never noticed the lamps staying on. The lamps turn ON when you open the door and they stay ON when you close it for about 30 seconds. The same set of lamps double as Map lights with two ON/OFF buttons in the mirror. I do not remember turning on a map light but may have done by accident the last time I washed the car and cleaned the mirror. The last wash was the morning before all this crap started.

Dodged an expensive bullet on this one. The real test will be to see if it starts after spending the night in our garage.

Last edited by Arkay; 08-10-2010 at 04:26 PM. Reason: typos
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Old 09-27-2010, 02:50 PM   #10
mavrick331
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Quote:
Originally Posted by Dick Kriss View Post
On Monday the dealership called saying it could be the $1,000 BCM (Body Control Module) because the vehicle was drawing 6 amps with the key OFF. The tech was trying to find the short or whatever that killed two batteries. He was having to do it the old fashion way, one circuit at a time. The service writer called back at the end of the day saying the new battery was okay that it charged fine and the tech found the interior lamp ON so he turned it OFF. The excessive current draw stopped but he wanted to let it sleep over night in his stall and check it in the morning. They called Tuesday and I have the car back. For only $114 we went from Intensive Care to Release.

I have no idea how the interior lamps got turned ON but it was dying on me during the day and I probably never noticed the lamps staying on. The lamps turn ON when you open the door and they stay ON when you close it for about 30 seconds. The same set of lamps double as Map lights with two ON/OFF buttons in the mirror. I do not remember turning on a map light but may have done by accident the last time I washed the car and cleaned the mirror. The last wash was the morning before all this crap started.

Dodged an expensive bullet on this one. The real test will be to see if it starts after spending the night in our garage.
I had the exact same issue on my 03', I went circuit by circuit, never could narrow it down to one... Went to get a glass of water at 2am, looked out the door leading to the garage and saw a light on in the car!!! What a waste of time that was....
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Old 09-28-2010, 02:31 AM   #11
Bill Curlee
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Quote:
Originally Posted by Dick Kriss View Post
On Monday the dealership called saying it could be the $1,000 BCM (Body Control Module) because the vehicle was drawing 6 amps with the key OFF. The tech was trying to find the short or whatever that killed two batteries. He was having to do it the old fashion way, one circuit at a time. The service writer called back at the end of the day saying the new battery was okay that it charged fine and the tech found the interior lamp ON so he turned it OFF. The excessive current draw stopped but he wanted to let it sleep over night in his stall and check it in the morning. They called Tuesday and I have the car back. For only $114 we went from Intensive Care to Release.

I have no idea how the interior lamps got turned ON but it was dying on me during the day and I probably never noticed the lamps staying on. The lamps turn ON when you open the door and they stay ON when you close it for about 30 seconds. The same set of lamps double as Map lights with two ON/OFF buttons in the mirror. I do not remember turning on a map light but may have done by accident the last time I washed the car and cleaned the mirror. The last wash was the morning before all this crap started.

Dodged an expensive bullet on this one. The real test will be to see if it starts after spending the night in our garage.

Go buy TWO bottles of JACK DANIAL'S and Give ONE to the the technician and the other to the service manager. They are ON YOUR SIDE and " HONEST"!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!

Tell them that they have my VOTE for the GOOD GUY award!

Bill Curlee
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Old 09-28-2010, 08:56 AM   #12
printmanjackson
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map light? wow

everyone needs to take note of this because you would not see it on.


that's one of the few DEALERSHIPS I have heard of.
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Old 09-28-2010, 11:55 AM   #13
MUKAK
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Quote:
Originally Posted by printmanjackson View Post
map light? wow

everyone needs to take note of this because you would not see it on.


that's one of the few DEALERSHIPS I have heard of.
i took those off a long time ago....... my kids used to play with them and leave them on (my BCM IS SAFE!!!!!!!!!!!!!)
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