GM Service Manual Online
For 1990-2009 cars only

Interior Lamps

The interior lamps consist of 2 groups. The first group are those lamps which may not be dimmed. The 2nd group includes lamps that may be dimmed.

    • Door courtesy lamp - LF
    • Door courtesy lamp - RF
    • Dome lamp - center
    • Dome lamp - front
    • Inside rearview mirror lamps
    • I/P compartment lamp
    • Rear compartment lamps
    • Vanity mirror lamp

Courtesy Lamps

The rear electrical center (REC) applies voltage to the cargo lamps and the I/P compartment lamp with individual control circuits. The REC applies voltage to the dome/reading lamps and the left and right vanity mirrors through the inadvertent courtesy lamp control circuit. In the event that the dome lamp, reading lamp, or vanity mirror lamp were to remain illuminated for more than 20 minutes with the ignition switch in the OFF position, the REC will deactivate the inadvertent courtesy lamp control circuit to prevent battery discharge. The dome lamps are controlled by a 3 position (OFF, DOOR, ON) switch. When the dome lamp switch is placed in the DOOR position the lamps are controlled by the REC by grounding the courtesy lamp control circuit. When any door or the rear hatch is opened, the jam switch contacts close and the REC receives a door or rear hatch open input. If the REC receives a door lock or unlock input or a rear hatch open input, the REC will apply voltage to the individual courtesy lamp control circuits illuminating the courtesy lamps.

I/P Compartment Lamp

The REC applies battery voltage to the I/P compartment lamp through the I/P compartment lamp control circuit. When the I/P compartment is opened, the I/P compartment lamp switch contacts close allowing voltage to flow from the REC through the switch contacts to ground G205 illuminating the I/P compartment lamp.

Keyless Entry Interior Illumination

When the driver uses the remote function actuator (RFA) transmitter to unlock the doors or press the panic button, the REC will keep the courtesy lamps ON for 30 seconds. If the door locks are activated to the UNLOCK or LOCK position, or if the ignition switch is turned to either the RUN or CRANK position, the courtesy lamps turn OFF immediately. The REC keeps the courtesy lamps on for 40 seconds after an alarm event is completed.

Rear Compartment Lamps

The REC applies battery voltage to the rear compartment lamps through each rear compartment lamp control circuit. The rear compartment lamps are provided ground permanently at G401 for the right and G403 for the left. When the REC receives a rear hatch open input, the REC will activate the rear compartment lamp control circuits to provide battery voltage to the rear compartment lamps.

Interior Lamps Dimming

Interior lamps dimming are lamps that may be dimmed by operating the instrument panel (I/P) dimmer switch. This group consist of the following lamps:

    • Dome lamp - front
    • Hazard switch
    • HVAC control head assembly
    • Transmission range selector
    • Sunroof switch
    • Instrument Panel Cluster (IPC)

The instrument panel (I/P) lamp dimmer switch is incorporated into the headlamp switch assembly. The I/P dimmer switch is used to increase and decrease the brightness of the interior backlighting components. The I/P dimmer switch provides a voltage signal that will increase as the brightness of the lights are increased and decrease as the brightness of the lights are decreased. The instrument panel cluster (IPC) provides a low reference signal and a 12 volt reference to the I/P dimmer switch. When the I/P dimmer switch is placed in the desired position, the dimmed voltage setting is applied from the I/P dimmer switch through the I/P dimmer switch signal circuit to the IPC. The IPC interprets the signal and applies the dimmed voltage to the I/P lamps supply voltage circuit and the interior backlighting components dim to the requested level. Ground for the I/P dimmer switch is provided at the headlamp switch low reference circuit through the IPC.