GM Service Manual Online
For 1990-2009 cars only

The vehicle lighting system consists of the exterior lighting and of the interior lighting. The exterior lighting include the following lamps:

    • Headlamps
    • Daytime running lamps
    • Fog lamps
    • Park lamps
    • Tail lamps, including the license lamp
    • Turn signal lamps and emergency flashers
    • Stoplamps, including the center high mounted stoplamp (CHMSL)
    • Backup lamps

Headlamps

The headlamps are operated when the driver places the headlamp switch in the ON position. If the headlight switch is left in the ON position, after the ignition switch has been turned OFF, the headlights will remain on until turned off or the battery runs dead. With the headlights in the low beam position, the high beams may be momentarily turned on or flashed with the dimmer switch handle. The flash-to-pass feature is accomplished by pulling the dimmer switch handle toward the driver. The headlights may be switched to high beam with the opposite movement of the dimmer switch lever.

The daytime running lamps (DRL) illuminate the [high] low beam headlights at a reduced intensity. With the headlamp switch placed in the OFF position, during day light conditions, the BCM will activate the DRL. The DRL will operate when the ignition switch is in the RUN position, the gear selector is not in the PARK position and the parking brake is released. When these conditions have been met and the ambient light sensor indicates daytime conditions, the DRL will illuminate. Any function that turns on the headlights will cancel DRL operation.

DRL operation in Manual Transmission equipped vehicles will occur when the ignition switch is in the RUN position, and the parking brake is released.

Fog Lamps

With the ignition switch in the ON position, and the park lamps or low beam headlights on, the fog lights will illuminate when the driver presses the fog lamp switch. The state of the fog lamps (on or off) will remain the same until the fog lamp switch is pressed again, or the ignition switch is cycled OFF and ON. Fog lamp operation will be cancelled whenever the park lamps, are turned OFF or the high beam headlights have been selected.

Turn Signal Lamps

The turn signal lamps may only be activated with the ignition switch in the ON position. When the turn signal switch lever is placed in either the left or right hand position, the respective turn signal lamps will flash. The instrument panel cluster (IPC) turn signal indicator, either left or right will also flash.

When the hazard switch is pressed, all turn signal lamps will flash including both IPC turn indicators.

Stop Lamps

When the driver presses the brake pedal, all stop lamps and the center high mounted stop lamp (CHMSL) illuminate.

Park/Tail Lamps

The park lamps, including the license lamps, are turned on when the headlamp switch is placed in the PARK or HEADLAMP position, or anytime the headlights are requested. If the park lights are turned on after the ignition switch has been turned OFF, they will remain on until turned off or the battery runs dead.

Remote Keyless Entry Exterior Lamp Illumination

When the remote function actuation (RFA) module receives a door unlock command from the remote function actuator transmitter, the RFA module will ground the door unlock signal circuit to the BCM, [send a class 2 message to the body control module (BCM),] indicating that an UNLOCK command has been received. The BCM will then flash the daytime running lamps (if selected ON in personalization). With all the doors closed, and the RKE transmitter is used to lock the doors, the daytime running lamps (if selected ON in personalization). The daytime running lamps will not flash if the rear compartment is opened using the RKE transmitter.

Backup Lamps

When the driver selects the REVERSE position, the backup lights illuminate.

Interior Lamps

The interior lighting group consists of the following lamps:

    • Courtesy lamps
    • Dome lamps
    • Foot well lamps
    • IP compartment lamp
    • Rear compartment lamps
    • Roof rail courtesy lamps and/or reading lamps
    • The underhood lamp
    • Vanity mirror lamps

Courtesy Lamps

The courtesy lamps, including the reading lamps, may be manually turned on by placing the IP dimmer switch in the DOME position. When the dome lamp switch is in the DOOR position, the dome lamp will illuminate when a door is opened. When a front door is opened, the dome and courtesy lamps turn on. After all the doors have been closed the courtesy lamps will remain illuminated approximately 10 seconds after the last door closes. The courtesy lamps will normally turn off using the theater dimming feature. The courtesy lamps will also turn off immediately 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. When the driver places the dome lamp switch in the OFF position, the dome lamp will be disabled.

Keyless Entry Interior Illumination

When the remote function actuation (RFA) module receives a door unlock command from the remote function actuator transmitter, the RFA module will ground the door unlock signal circuit to the BCM, [send a class 2 message to the body control module (BCM),] indicating that an UNLOCK command has been received. The BCM must have inputs that indicate that the ignition switch is OFF, all the doors are closed. The BCM will then activate the inadvertent power supply, providing battery positive voltage and also a pulse width modulated (PWM) ground to the interior lamps. The BCM will keep the courtesy lamps on approximately 20 seconds and then turn them off through the theater dimming feature. If the door locks are activated to the LOCK position, the courtesy lamps will deactivate immediately. When the ignition switch is turned to either the ON or RUN position the courtesy lamps will deactivate in approximately one second.

Reading Lamps

The rear view mirror contains two map lamps, each map lamp may be manually turned on or off using it's own switch.

Rear Compartment Lamp

When the rear compartment (trunk lid) is opened, the rear compartment lamp illuminates.

Interior Lamps Dimming

The interior lamps dimming group may use a combination of vacuum fluorescent (VF) illumination and of incandescent lamps. The interior lamps dimming group consists of the following lamps:

    • Door switches and window switches
    • HVAC control head assembly
    • Radio
    • The instrument panel cluster (IPC)
    • Transaxle Shift Indicator Lamp

When the headlight switch is turned to the PARK or HEAD position, all incandescent back lighting turn on at the dimming level indicated by the IP dimmer switch. When the IP dimmer switch is moved from MIN to MAX, all vacuum fluorescent (VF) [liquid crystal display LCD], [light emitting diode LED] displays, as well as all incandescent back lighting respond from Minimum intensity to maximum brightness in response to the IP dimmer switch. The ambient light sensor supplies the BCM with a signal for daytime conditions or for low light conditions.

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