Circuit Description
WARNING: This page is about a different car, the 2002 GMC Safari and 2002 Chevrolet Astro. However, it is still accessible from the selected car via links, so may be relevant.
The body control module (BCM) controls the ground of the courtesy lamp relay on the courtesy lamp relay coil control circuit. When the BCM receives a signal from a door jamb switch, a signal to unlock the doors from the remote control door lock module receiver module or the dome lamp switch being turned ON, the BCM grounds the relay and turns ON the courtesy lamps.