Circuit Description
WARNING: This page is about a different car, the 2003 Buick Regal and 2003 Buick Century. However, it is still accessible from the selected car via links, so may be relevant.
The BCM controls the ground for the courtesy lamps through the courtesy lamp low control circuit. The BCM applies voltage to the courtesy lamps through the courtesy lamps supply voltage circuit. Ground for the courtesy lamps is applied from G201 to the BCM.