Battery is flat after it sits a while

Tiny
GRAVESENDER
  • MEMBER
  • 2006 CHEVROLET COBALT
  • 109,000 MILES
I have the 2006 cobalt and I have a battery drain issue I used my volt meter and tested every fuse in the car after letting it sit for a half hour it turns out my bcm2 is draining 6.99mv so Im thinking I need to replace my bcm is there something im missing I was also wondering if I can replace the bcm with a used one I am a back yard mechanic but suck with electrical issues I read on the net that the car will reflash the bcm if the key is left in the on position for 10min then off then back in the on position for another 10 min would appreciate your info by the way there are no mil lights that come on and I do not have power locks its a plain jane no accessory cobalt
By the way car runs fine after I give it a jump isn't the alternator its charging when driving but drains when it sits

thank you
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Monday, August 13th, 2012 AT 9:16 PM

13 Replies

Tiny
RASMATAZ
  • MEMBER
Go to this walk thru link: http://www.2carpros.com/articles/car-battery-dead-overnight
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Monday, August 13th, 2012 AT 9:23 PM
Tiny
SATURNTECH9
  • EXPERT
Mv is a voltage reading not a amp drain reading. How are you doing your parastic draw test?
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Monday, August 13th, 2012 AT 9:23 PM
Tiny
GRAVESENDER
  • MEMBER
I am testig the two leads fro each fuse in the car looking for power still drawing
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Monday, August 13th, 2012 AT 9:34 PM
Tiny
RASMATAZ
  • MEMBER
Sat9 let him go here -we wait for him-Go to this link: http://www.youtube.com/watch?v=yFCT-YZbU5o
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Monday, August 13th, 2012 AT 9:38 PM
Tiny
SATURNTECH9
  • EXPERT
I always do at the battery cable where it attaches to the battery. You break the connection to battery and measure milliamp draw not voltage. Measuring a draw from the body control module can be tricky.
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Monday, August 13th, 2012 AT 9:41 PM
Tiny
GRAVESENDER
  • MEMBER
Did everything from the first post going to try from the second post I just watched a video on you tube from a mechanic and that's how he tested the draw without disconnecting battery ill try the light just tried the light it was the bcm2 fuse so un pluged my radio and the drain was gone I pulled the cd that was in it out and replugged it in and turned the key on and off the drain was still gone does that mean I cant play cds I never put the stations in maybe its the memory of the radio im going to experiment some more.

I was wrong my bulb burned out it went from 15 ma to 2 ma after I disconnected the neg and the bcm fuse and reconnect the fuse and read the mila-amps between neg cable and post is that normal or should it read 0 I pulled every fuse

Ok this is my final post checked everything with the test light and with the multimeter all the ways I was told, watched all the videos made sure every light was off trunk, hood, dome ect here is my conclusion the bcm2 fuse is drawing 0.15mA when I go to the negative cable after I went for a ride and waited 15 min for every thing to go into sleep mode checked it again between the neg cable and post it read.15mA a 3 min later with the neg cable still disconnected I checked it again and the it read.02mA I did this like 5 times just to make sure nothing changed its always the same so does it sound like the bcm or is there more for me to check (if so can I instal a used one that's been tested)

thank you for your help
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Monday, August 13th, 2012 AT 11:13 PM
Tiny
SATURNTECH9
  • EXPERT
I posted the way chevy wants you to measure and test for a draw. Let me know what you find.
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Wednesday, August 15th, 2012 AT 4:10 PM
Tiny
GREGSON
  • MEMBER
I know this is an old post but what was the final solution to the bcm2 fuse draw
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Sunday, September 18th, 2016 AT 7:38 AM
Tiny
KEN
  • ADMIN
The problem was caused by the BCM not going into sleep mode which keeps the electrical system alive which makes the battery drain. You will need to have a garage reprogram the BCM once it is replaced, Here is its location (below)

Please let us know what you happens.

Cheers, Ken
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Thursday, November 16th, 2017 AT 11:49 AM
Tiny
AH3269
  • MEMBER
  • 2006 CHEVROLET COBALT
  • 2.0L
  • AUTOMATIC
  • 160,000 MILES
I have a chevy cobalt that has had a drain. We pulled all the fuses and it was the audio system. We have taken the radio out and it no longer drains. Wondering what is cause the radio to pull from the battery? Bad wiring or what? Also just had the BCM replaced and now the bright lights don't work. Regular lights work but when trying to use brights, they don't have any power? Thanks
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Wednesday, November 22nd, 2017 AT 10:19 AM (Merged)
Tiny
RIVERMIKERAT
  • MEMBER
Radio issue: That depends on how much draw there way. The memory and clock circuits are constant draws of as much as an amp.
The stereo system is actually two subsystems-The head unit, the part you see and adjust, and the amplifier, you don't see or touch this. The amplifier is switched on an off by a switching power lead from the head unit. If that power lead is constantly hot, the amp will be on all the time. That power lead sends a switching voltage (12v @ 1 amp) to a relay inside the amp which switches the main power. That relay could also be fused, maintaining main power to the amp constantly on.

Headlight issue: The headlights in your car are controlled by the switch and two relays. One of those relays in under the hood in the main relay/fuse box. The other is inside the BCM. Use a test light or meter to see if power is reaching the high beams (pink wire according to my reference). If not, check the high beam relay. You'll find in the main fuse/relay box under the hood next to the left strut tower. It SHOULD be labeled. Each high beam also has a fuse in that box that you should check.

In the future, please start two question threads if you have multiple issues this way other users can search our q&a database easier to resolve their problems. Thank you.
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Wednesday, November 22nd, 2017 AT 10:19 AM (Merged)
Tiny
GIBBONSL
  • MEMBER
  • 2006 CHEVROLET COBALT
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 59,000 MILES
Electrical problem
2006 Chevy Cobalt 4 cyl Front Wheel Drive Automatic 59000 miles

2006 Chevy Cobalt 4 cyl Two Wheel Drive Automatic 59000 miles

I got stuck in the snow and finally got out got to work and my key was stuck in the acc position the engine would cut off but the rest of the car wouldn"t a friend of my snatch the key out in the acc position 12 hour later the car still started so I was able to drive home still with the inginition still stuck in the acc position the next morning I was not able to stsrt the car because the battery had went down so I recharge the battery but now it will not say nothing the information screen say the engine is lock the engine light stay on and the two lock are on Can you please tell me how to get it started or what to replace oh yeah the shifter I do not have to push in the pawl for it to move through gear like I had to before what about the shifter it a floor shifter
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Wednesday, November 22nd, 2017 AT 10:20 AM (Merged)
Tiny
JACK42
  • MEMBER
Sounds like the igniton tumbler or the steering column will be the problem. You will need to take it apart to remove the tumbler to see if you can manually work the column to see which is causing it to stick in the acc position.
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Wednesday, November 22nd, 2017 AT 10:20 AM (Merged)

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