[Ian W]

I have had my mechanic check my battery which has gone dead after period of inactivity and it appears that the battery if fine but there is a 300+ mAmp drain whcih is about 5-10 times what is should be. He feels it might be linked to eh BCM. Any thoughts?

 

[shabby]

Pull a fuse and use a volt meter to read the amperage between the two contact points, then pull the next one and so forth until you find the circuit draining the battery.

 

[JohnWR]

I have had my mechanic check my battery which has gone dead after period of inactivity and it appears that the battery if fine but there is a 300+ mAmp drain whcih is about 5-10 times what is should be. He feels it might be linked to eh BCM. Any thoughts?

How soon after powering the car off was that current measured? Also, what period of inactivity kills the battery.

 

[HHGadget]

Doesn’t the car stay energized for 10 minutes or so after turning off for things like power windows and other accessories ?

 

[JohnWR]

Doesn’t the car stay energized for 10 minutes or so after turning off for things like power windows and other accessories ?

Yes, there is actually a ramp-down of power consumption as systems go to sleep, and different ones wake up when the door is opened, the key is inserted, and so on.

 

[Ian W]

turns out there was short or something in the OnStar modu le. I don't use OnStar so he disconnected it at the fusebox and the 300 mA drain went away. Can anyone comment on whether the OnStar is involved in anything else important.

 

[JohnWR]

turns out there was short or something in the OnStar modu le. I don't use OnStar so he disconnected it at the fusebox and the 300 mA drain went away. Can anyone comment on whether the OnStar is involved in anything else important.

Glad you found the problem.
The module doesn't do anything else, but that fuse might power something else. I will check and post tonight if someone doesn't beat me to it.

 

[JohnWR]

Fuse #56 powers the Digital Radio Receiver (XM), Vehicle Communication Interface Module (OnStar), an the Remote Control Door Lock Receiver (Keyless Entry).