Voltage is available at all times from the CTSY fuse 3 to the courtesy lamps, the dome and reading lamps, and the instrument panel (IP) compartment box lamp. The courtesy lamps and the dome and reading lamps illuminate when the headlamps and panel dimmer switch or one of the door jamb switches provides a ground path.

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