GM Service Manual Online
For 1990-2009 cars only

Interior Lamps

The interior lighting consist of 2 groups. The first group includes lamps that may not be dimmed. The non dimming lamps are:

    • The dome lamps - Coupe
    • The rear courtesy lamps - Convertible
    • The inside rearview mirror lamps
    • The IP compartment lamp
    • The rear compartment lamp

Courtesy/Illuminated Entry Lamps

Within the non dimming lamps group are the courtesy/Illuminated entry lamps. These lamps may be manually turned on by placing the IP dimmer switch in the ON position. The following lamps are in the courtesy/Illuminated entry lamps group:

    • The dome lamps - Coupe
    • The rear courtesy lamps - Convertible
    • The inside rearview mirror lamps
    • The rear compartment lamp

The courtesy lamps will also illuminate when the illuminated entry feature is active, when the ignition is OFF and one of the following actions occur:

    • The LH door is opened.
    • The RH door is opened.
    • The rear compartment is opened.

After the doors and the rear compartment have been closed, the courtesy lamps will remain illuminated approximately 30 seconds. 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.

Exit Illumination

The courtesy lamps will also illuminate for approximately 40 seconds when the key is removed from the ignition prior to any door being opened. The courtesy lamps will remain illuminated for 5 seconds after the doors have been opened.

The COURTESY fuse in the IP fuse block, supplies battery positive voltage to the body control module (BCM). When the rear compartment or any door is opened, the door lock switch contacts close and a door ajar input is received by the BCM. The BCM will then supply battery positive voltage to all non dimming interior lamps. The BCM will also pull low the courtesy lamps control circuit, illuminating the courtesy lamps.

The courtesy lamps will normally turn off using the theater dimming feature. During theatre dimming, the BCM provides a pulse width modulated ground to all courtesy lamps that gradually dims the courtesy lamps. 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.

Inadvertent Power Feature

Inadvertent power feature provides a similar function for the interior lamps as a retained accessory power feature. The BCM will energize the courtesy lamps supply voltage circuit when the BCM is in the active state (awake). When the courtesy lamps supply voltage circuit is energized, it supplies voltage to all the interior lights. The BCM will continue to supply voltage to the interior lamps after the ignition is turned OFF so that the interior lamps may be operated.

The inadvertent power feature will also act as battery run down protection by deactivate the courtesy lamps supply voltage circuit after 10 minutes once the BCM becomes inactive, ignition OFF and no BCM input activity.

Keyless Entry Interior Illumination

When the driver uses the remote function actuator transmitter to unlock the doors or rear compartment, the BCM will illuminate the courtesy lamps for approximately 40 seconds. When the courtesy lamps are illuminated, and 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.

Inside Rearview Mirror Lamp

The inside rear view mirror lamp is turned ON by the IP dimmer switch, the inside rear view mirror switch, or during illuminated entry.

During illuminated entry or when the IP dimmer switch is ON the BCM wakes up and then energizes the courtesy lamps supply voltage circuit, suppling voltage to all interior lamps. The BCM also pulls the courtesy lamp control circuit low, providing ground to the inside rear view mirror lamp and all courtesy lamps, illuminating all courtesy lamps.

The inside rear view mirror lamp can be turned on manually from the inside rear view mirror switch. The BCM supplies voltage through the courtesy lamps supply voltage circuit when the BCM is awake. Manually turning on the inside rear view mirror switch provides a ground path, illuminating the rearview mirror lamp.

IP Compartment Lamp

The BCM provides battery positive voltage to the IP compartment lamp though the courtesy lamps supply voltage circuit. When the IP compartment is opened, the IP compartment switch closes providing a ground to the IP compartment lamp, illuminating the IP compartment lamp.

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 Door switches and the window switches
    • The HVAC control head assembly
    • The Radio
    • The instrument panel cluster (IPC)

When the ignition switch is turned to the ON position, the vacuum fluorescent (VF) displays, which include the radio and HVAC control assembly, turn on at maximum brightness. When the park lamps are on, all incandescent back lighting turns on at the dimming level indicated by the IP dimmer switch. At the same time all vacuum fluorescent (VF) displays dim to match the indicated dimming level.

Battery positive voltage is supplied to the IP dimmer switch from the headlamp switch or the DRL control Module when the park lamps are on. When the driver selects a dimming setting by moving, the IP dimming switch potentiometer, all incandescent back lighting lamps are provided with a specific voltage. When the IP dimmer switch is moved from MIN to MAX, all vacuum fluorescent (VF) displays, as well as all incandescent back lighting respond from minimum intensity to maximum brightness in response to the IP dimmer switch.