Battery Rundown Protection / Inadvertent Power
WARNING: This page is about a different car, the 2003 Pontiac Grand Prix. However, it is still accessible from the selected car via links, so may be relevant.
The body control module used in this vehicle controls the lighting system through circuits that enable both the exterior lamp functions of park, head and fog lamps as well as the interior lamps. The BCM opens these enabling circuits 20 minutes after the ignition switch is turned OFF with no lamp switch activity. If the ignition switch is turned to any position other than OFF, or if a lamp switch is activated, during this 20 minute period the timer will reset for another 20 minutes.
The inadvertant load (battery rundown) protection feature is mileage-sensitive. Vehicles with less than 15 total driven miles (24 kilometers) have a time-out of 162 to 198 seconds instead of 20 minutes.