GM Service Manual Online
For 1990-2009 cars only

Interior Lamps

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

Dome Lamp

The DOME PANEL circuit breaker in the instrument panel (IP) fuse block supplies battery positive voltage to the dome lamp. A path to ground is provided for the dome lamp through the IP lamps dimmer switch or the door jamb switch. When the driver places the IP dimmer switch in the dome lamp ON position or opens the driver's door, the dome lamp will illuminate.

Keyless Entry Interior Illumination

When the driver uses the door key in order to unlock the doors, the illuminated entry module, or with RKE, the remote control door lock receiver receives a door unlock signal. The module or receivers signal comes from the door jamb switches which ground at G200 and G201. The module or receiver must have inputs that indicate that the ignition switch is OFF, the courtesy lamp switch is OFF and all the doors are closed. The module or receiver will then activate the dome lamp. The dome lamp will remain on, approximately 15 seconds after the door is closed. 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, or presses the panic button, the module or receiver will keep the dome lamp on approximately 40 seconds. When the driver uses the remote function actuator transmitter to lock the doors, the module or receiver will keep the dome lamp on approximately 2 seconds. When the ignition switch is turned to either the RUN or CRANK position the dome lamp will turn off immediately.

Interior Lamps Dimming

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

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

When the ignition switch is turned to the ON position, the radio's vacuum fluorescent (VF) displays turn on at maximum brightness. When the park lamps are on, all incandescent back lighting turn 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 through the PARK LPS 20 A fuse 9 in the IP fuse block to the switch. The panel dimmer switch potentiometer receives its voltage from the headlamp switch. When the driver selects a dimming setting by moving the IP dimming switch potentiometer, the ILLUMN 10 A fuse 14 in the IP fuse block receives a specific voltage. All incandescent back lighting lamps are then provided with the same specific voltage from the ILLUMN 10 A fuse 14 in the IP fuse block. The interior dimming lamps are then grounded at G201, G101, and G400. 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.

The driver may select parade mode by manually turning the IP dimmer switch in the parade mode. The LED dimming signal circuit supplies voltage to the instrument panel cluster and radio for a park lamp on input, and the displays will become full bright.