Panel Lamps Dimmer Circuit

The panel lamps dimmer circuit actually includes several circuits. These circuits control the back lighting illumination and dimming level of the headlamp switch, the dimmer module, the automatic transmission gear selector bezel lamp as well as the center floor console cup holder lamps. All lamps in the panel lamps dimmer circuits are provided a path to ground at all times through a hard wired ground circuit. These lamps are illuminated by a 12-volt Pulse Width Modulated (PWM) output of the BCM or the door control modules (also known as the Driver Door Module/DDM or Passenger Door Module/PDM) through several panel lamps dimmer circuits.

This shared PWM output synchronizes the selected illumination intensity level of all the lamps in the panel lamps dimmer circuits. The BCM uses hard wired resistor multiplexed inputs from the rotary exterior lighting control knob of the headlamp switch to determine when the exterior lighting is turned ON and from the thumbwheel of the dimmer module to determine the dimming level selection. Then the BCM provides the appropriate PWM outputs through the panel lamps dimmer circuits as well as electronic dimming level  messages over the CAN data bus to other electronic modules in the vehicle.

The Instrument Cluster (IC) (also known as the Common Instrument Cluster/CIC) and the Integrated Center Stack (ICS) use the electronic dimming level  messages to control the illumination intensity of their own back lighting, controls and display units. In addition, when the interior lighting thumbwheel of the dimmer module is moved to the PARADE (or funeral) mode detent position, all of the electronic display units are illuminated at their full intensity levels for increased visibility when the vehicle is driven during daylight hours with the exterior lighting turned ON. The PARADE mode has no effect on the illumination intensity of incandescent panel lamps.