The I/P lamp dimmer switch controls the brightness of the incandescent lamps and Vacuum Fluorescent (VF) displays. The incandescent lamps are located in various components (see schematics) and the VF displays are located in the radio, instrument cluster and heater-A/C control (with RPO CJ2).

The brightness of the incandescent lamps is determined by a variable voltage signal produced by the I/P lamp dimmer switch.

The brightness of the Vacuum Fluorescent (VF) displays is controlled by two signals: the park lamps on signal (circuit 230) and the VF dimming signal (circuit 308). With the park lamps on, the VF display of the radio, heater, A/C control (with RPO CJ2) and the instrument cluster will dim for nighttime viewing. When the park lamps on signal is not present (park lamps off), the VF displays are at high brightness for daytime viewing. When the park lamps are on, the I/P lamp dimmer switch provides a signal (VF Dimming Signal circuit 308) which controls the brightness of the VF displays when the I/P lamp dimmer switch is adjusted.