Dashboard / Instrument Panel: Description and Operation

During normal operation, the Instrument Panel Dimming Rheostat controls a small number of lamps on the 99 (BK/W) circuit. Most dimable lamps are fed through the Pulse Width Dimming Module, which duplicates the illumination level of the rheostat at a higher power output.

Certain lamps must be illuminated fully during the daytime and dimmed at night (484 [O/BK] circuits). This is accomplished by a switch in the Main Light Switch (in vehicle without Automatic Headlamps) or by the LCD Dimming Relay (in vehicles with the Automatic Headlamps).