GM Service Manual Online
For 1990-2009 cars only

The IP dimmer switch controls the following components:

    • The brightness of the incandescent lamps
    • The Vacuum Fluorescent (VF) displays

The incandescent lamps are located in various components. The VF displays are located in the radio.

Incandescent Dimming

The IP dimmer switch produces a variable voltage signal which determines the brightness of the incandescent lamps.

Vacuum Fluorescent (VF) Dimming

The VF dimming signal controls the brightness of the VF displays. The VF display of the radio will dim for low light viewing with the park lamps ON. The VF displays are at high brightness for daytime viewing with the park lamps OFF. When the park lamps are ON, the IP lamp dimmer switch provides a signal (VF Dimming Signal circuit 230) which controls the brightness of the VF displays when the IP dimmer switch is adjusted.

Park Lamp Dimming

When the park lamps are ON, the park lamps on signal (circuit 308) applies to the following components resulting in the dimming of the components for night time viewing:

    • The radio
    • The heater and A/C control (CJ2)
    • The trip calculator
    • The instrument cluster