Courtesy Lamp: Description and Operation

COURTESY LAMPS

The INTERIOR LIGHTS fuse supplies battery voltage to the body control module (BCM). The BCM applies battery voltage to the inside rearview mirror lamps through the courtesy lamp supply voltage circuit. The inside rearview mirror lamps are controlled by a 3 position (DOOR, OFF, ON) switch. When the inside rearview mirror switch is placed in the DOOR position, the lamps are controlled by the BCM. When any door is opened, the jam switch contacts close and the BCM receives a door-open input. If the BCM receives a door lock or unlock input or a rear hatch open input, the BCM will activate the courtesy lamp supply voltage circuit, providing battery voltage to the inside rearview mirror lamps. The BCM also provides ground to the inside rearview mirror lamps through the courtesy lamp control circuit.

The courtesy lamps will remain illuminated approximately 15 seconds after the last door closes. Courtesy lamps also turn ON prior to any door being opened, and remain illuminated approximately 30 seconds after the driver removes the ignition key.

The courtesy lamps will normally turn OFF using the theater dimming feature. The BCM provides a pulse width modulated ground to the courtesy lamps for the theater dimming feature. The BCM turns OFF the courtesy lamps if a door lock command is received after all of the doors are closed, or if the ignition switch is turned to either the ON or RUN position.

The BCM will provide interior lamp illumination in the event that an air bag has been deployed. Upon deployment of the air bag the inflatable restraint sensing and diagnostic module (SDM) will send a GMLAN serial data message to the BCM. The BCM will activate the interior lamps approximately 15 seconds after air bag deployment if the Photocell Status is DARK and the ignition is in the ON position. The interior lamps will remain illuminated until there is a change in the power mode.