GM Service Manual Online
For 1990-2009 cars only

Interior Lamps

The interior lighting consist of two groups. This first group includes lamps that may not be dimmed:

    • The Courtesy/Reading Lamps
    • The Vanity Mirror Lamps
    • The I/P and Rear Compartment Lamps

Courtesy/Illuminated Entry Lamps

The second group include lamps that may be manually turned on by placing the interior lamp switch in the DOME position, or by opening a door.

    • The Roof Rail/Reading Lamps
    • The Rear View Mirror Lamps

After all the doors have been closed the courtesy lamps will remain illuminated approximately 15 seconds after the last door closes. The courtesy lamps will also turn ON prior to any door being opened, and remain illuminated approximately 30 seconds when the driver removes the ignition key. The INT LAMP fuse in the fuse block, supplies battery positive voltage to the body control module (BCM). The protected battery output courtesy lamps circuit of the BCM supplies battery positive voltage to all interior courtesy lamps. When any door is opened the door jam switch contacts close and a door open input is received by the BCM. If a door lock or unlock input is received by the BCM, it will activate the protected battery output courtesy lamps circuit providing battery positive voltage to all interior courtesy lamps. Some of the courtesy lamps may also be used as reading lamps by placing the lamps switch in the ON or OFF position.

The courtesy lamps will normally turn OFF using the theater dimming feature. The BCM provides a pulse width modulated ground to all courtesy/reading, dome and inside rear view mirror lamps for the theater dimming feature. The BCM will immediately turn OFF the courtesy lamps if a door lock command is received with all the doors closed, or if the ignition switch is turned to either the ON or RUN position.

The courtesy lamps will also turn ON after an air bag deployment for approximately 15 seconds.

Keyless Entry Interior Illumination

When the driver uses the door key in order to unlock the doors, the BCM receives a door unlock signal. The BCM must have inputs that indicate that the ignition switch is OFF, the courtesy lamp switch is OFF and all the doors are closed. The BCM will then activate the interior lamps. The courtesy lamps will remain ON, approximately 15 seconds after the door is closed. The BCM will then turn them OFF through the theater dimming feature. If the door locks are activated to the LOCK position, or if the ignition switch is turned to either the RUN or CRANK position the courtesy lamps will turn OFF immediately.

When the driver uses the remote function actuator transmitter to unlock the doors, trunk or presses the panic button, the BCM will keep the courtesy lamps ON approximately 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 will turn OFF immediately. The BCM will also keep the courtesy lamps ON approximately 40 seconds, after an alarm event is completed.

Vanity Lamps

The protected battery output courtesy lamps circuit also provides battery positive voltage to each vanity mirror lamp. When the vanity mirror cover on the sunshade is opened, its switch closes to provide a ground circuit and the vanity lamp illuminates.

IP Compartment Lamp

The protected battery output courtesy lamps circuit also provides battery positive voltage to the instrument panel compartment lamp. When the I/P compartment is opened, its switch closes to provide a ground circuit and the I/P compartment lamp illuminates.

Rear Compartment Lamp

The protected battery output courtesy lamps circuit also provides battery positive voltage to the rear compartment lamp. When the rear compartment is opened, its switch closes to provide a ground circuit and the rear compartment lamp illuminates.

Interior Lamps Dimming

The second group includes lamps which may be dimmed. This group may use a combination of vacuum fluorescent (VF) illumination and of incandescent lamps:

    • The ashtray lamp
    • The automatic transaxle control position indicator
    • The door switches and the window switches
    • The driver seat heater switch
    • The driver information center (DIC)
    • The fog lamp switch
    • The HVAC control head assembly
    • The head-up display (HUD) dimmer switch
    • The radio
    • The trip calculator
    • The instrument panel cluster (IPC)
    • The steering wheel control switch

When the ignition switch is turned to the ON position, the VF displays, radio and HVAC control assembly, incandescent lamps, turn ON at maximum brightness. When the park lamps are ON and the ambient light sensor indicates low light conditions, all incandescent back lighting turn ON at the dimming level indicated by the IP dimmer switch. At the same time all VF displays dim to match the indicated dimming level. Battery positive voltage is supplied from the PARK LP fuse in the underhood fuse block to the headlamp switch. When the headlamp switch is in the PARK or HEAD position current flow is from IP lamps dimming control circuit in the headlamp switch. When the driver selects a dimming setting by moving, the I/P dimming switch potentiometer, all incandescent back lighting lamps are provided with a specific voltage. The incandescent back lighting lamps are then grounded at G200, G301 and G302. When the I/P dimmer switch is moved from MIN to MAX, all VF displays, as well as all incandescent back lighting respond from minimum intensity to maximum brightness in response to the IP dimmer switch.

The driver may select parade mode by manually turning ON the park lamps during daylight conditions. The front park lamp circuit supplies voltage to the IPC, radio and HVAC assembly for a park lamp on input, and the displays will become full bright.

Interior Lighting Modes

Perform the following procedure in order to change the interior lighting mode:

  1. Turn off the instrument panel (I/P) dimmer switch.
  2. Turn the ignition switch to the OFF position.
  3. Remove the MALL PGM fuse.
  4. Turn the ignition switch to the ACC position.

The body control module (BCM) sounds the chime a number of times equivalent to the BCM type installed on the vehicle. At this time the BCM has entered the feature customizing mode. In order to change the interior lighting, cycle the BCM sounds a chime a number of times equal to the lighting mode. The lighting modes are as follows:

    • Mode 1- Exit illumination and delayed illumination are disabled.
    • Mode 2- Delay illumination is enabled.
    • Mode 3- Exit illumination is enabled.
    • Mode 4- Exit illumination and delayed illumination are enabled.

Driver Controls and Modules

The driver controls include the following components:

    • The Emergency Flasher Switch
    • The Fog Lamp Switch
    • The Headlamp Dimmer Switch
    • The Headlamp Switch
    • The Interior Lamp Switch
    • The IP Dimmer Switch
    • The Stoplamp Switch
    • The Turn Signal Switch

The BCM module and the headlamp switch process the inputs and the controls. The ambient light sensor supplies the BCM with a signal for daytime conditions or for low light conditions:

    • The Ambient Light Sensor
    • The Body Control Module (BCM)
    • The Driver Information Center (DIC)
    • The Instrument Panel Cluster (IPC)

Battery Rundown Protection / Inadvertent Power

The body control module (BCM) used in this vehicle controls the lighting system through circuits that enable both the exterior lamp functions of park, head and fog lamps as well as the interior lamps. The BCM opens these enabling circuits 20 minutes after the ignition switch is turned OFF with no lamp switch activity. If the ignition switch is turned to any position other than OFF, or if a lamp switch is activated, during this 20 minute period the timer will reset for another 20 minutes.

The inadvertent load (battery rundown) protection feature is mileage-sensitive. Vehicles with less than 15 total driven miles (24 kilometers) have a time-out of 162 to 198 seconds instead of 20 minutes.