GM Service Manual Online
For 1990-2009 cars only

The CTSY LP fuse and the PARK LPS fuse supply voltage at all times to the following lamps:

    • The courtesy lamps
    • The dome lamps
    • The reading lamps
    • The IP compartment lamp

The following lamps turn on when the panel dimmer switch, the dome lamp overide switch or one of the door jamb switches close and provide a signal to the BCM to activate the courtesy lamp relay which provides a ground for the following lamps:

    • The courtesy lamps
    • The dome lamps
    • The reading lamps

The switches on the IP compartment box lamp and the vanity lamps provide ground paths when the switches close.

For more information, refer to Body Control System Circuit Description in Body Control Systems.