Diagnostic Information on Battery Draw No Start - Body Control Module, BCM Power Timer

When performing normal diagnosis on a battery that has gone dead overnight, a technician may notice that the vehicle has approximately 4.1 amp draw on the system. The draw may be steady or may drop down to a low milliamp reading for 1-2 seconds and then rise back up to the 4.1 amp range. If this amp draw condition is observed, check for aftermarket accessories or an improperly installed GM accessory that is wired into circuit 6815 (orange wire/full size trucks)/circuit 1732 (orange wire/all other vehicles) for courtesy lamps. Anytime aftermarket accessories are installed into the courtesy lamp circuit, it can cause the inadvertent power timer in the body control module (BCM) to keep resetting. The BCM will remain awake and cause the draw of approximately 4.1 amps.

When servicing a vehicle with this concern, back out pin 1 of the connector 2 at the BCM and see if the draw goes away. If the draw goes away, check for an aftermarket accessory (LoJack, non-factory DVD system, alarm, etc.) that is improperly installed in circuit 6815/circuit 1732.