Service Engine Soon Light With A P1682 and/or A Battery Draw No Start - keywords accessory aftermarket bcm crank dead intermittent no ses wire wiring

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Some customers may comment on the Service Engine Soon (SES) light coming on, or the battery going dead overnight. During diagnosis technicians may find a 4.1 amp draw on the electrical system. The draw may be steady or may drop down to a low milliamp reading for 1-2 seconds and then rise back up near 4.1 amps. This concern may be caused by aftermarket accessories or an improperly installed GM accessory that is wired into circuit 1732 for the courtesy lamps.

Anytime aftermarket accessories are installed into the courtesy lamp circuit the inadvertent power timer in the body control module (BCM) may continuously reset. If this occurs the BCM may remain awake causing excessive battery drain.

When servicing a vehicle with this concern, back out pin 1 of 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 wired into circuit 1732.

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.