GM Service Manual Online
For 1990-2009 cars only

The Headlamp and Panel Dimmer Switch is the controlling component for the interior dimming function. This switch uses an internal rheostat to allow the customer to set the dimming to a desired setting.

Power is available to the Headlamp and Panel Dimmer Switch at all times from the PK LMPS fuse #9 through CKT 240 (ORN). Once the switch is turned to either the Park Lamp or Headlamp function, parade dimming is capable through CKT 1382 (PPL/WHT) to the illumination lamps of the following components:

    • Transfer Case Switch Transfer Case Controls.
    • Radio
    • Instrument Cluster

Power is also available for controlled dimming through the rheostat to the ILLUM fuse #14 through CKT 44 (DK GRN) when in one of the lighting functions. From the ILLUM fuse power is sent through CKT 8 (GRY) to the following components:

    • Headlamp and Panel Dimmer Switch.
    • Liftgate Release Switch
    • Radio
    • Window Wiper/Washer Switch, Rear
    • Automatic Transfer Case Controls
    • Automatic Transfer Case Select Switch
    • Fog Lamp Switch
        Ground for the above components is G200, through CKT 150 (BLK).
    • Front and Rear, Auxiliary HVAC Control Switch Lamps
    • Rear AC Selector Switch
        Ground for the HVAC Controls is G400, through CKT 150 (BLK)
    •  Instrument Cluster
        Ground for the Instrument Cluster runs through CKT 451 (BLK/WHT) to both ground G103 and G104.