Dimmer Switch: Description and Operation

CIRCUIT OPERATION

The Body Computer Module (BCM) generates two types of dimming signals: one for the incandescent bulbs (keyboard backlighting) and another for the LCD displays.

These two pulse width modulated (PWM) dimming signals are based upon the ambient light conditions sensed by the Twilight Photocell, the Instrument Panel Dimming Control setting, and the Park Lights and Headlight inputs. The ECM detects these inputs and generates the corresponding outputs for the LCD displays and keyboard backlighting.