Dimmer Switch - Operation

OPERATION

The dimmer module uses a single resistor multiplexed output for each switch thumbwheel to control the many functions and features it provides. The switch receives a clean ground from the Body Control Module (BCM) (also known as the Common Body Controller/CBC) on a multifunction switch MUX return circuit. It then provides outputs to the BCM on a panel lamps dimmer signal circuit to control panel dimmer and interior lighting functions, or on a dimmer environmental lighting circuit to control ambient (halo) lighting functions.

On vehicles equipped with a remote manual headlamp leveling system, the dimming module also receives a battery voltage input on a park/tail/running lamps feed circuit whenever the exterior lighting is turned ON. It then provides outputs to the BCM on a headlamp leveling switch to module signal circuit to control the headlamp leveling function.

The dimmer module illumination circuit receives a path to ground at all times through an instrument panel ground circuit. The illumination level is controlled by a Pulse-Width Modulated (PWM) output received from the BCM on a panel lamps driver circuit. The BCM controls this output based upon the panel lamps dimmer signal circuit input from the dimmer module.

The dimmer module operates as follows:

- Ambient (Halo) Lighting Control - On vehicles so equipped, the right thumbwheel on the dimmer module is rotated to the ambient DEFEAT or one of the six ambient dimmer detent positions to control the ambient (halo) lighting level. The dimmer module provides the appropriate resistor multiplexed output to the BCM over the dimmer environmental lighting circuit. The BCM reads and responds to this input by providing the appropriate control outputs through internal HSDs over the liftgate courtesy feeds driver circuit.
- Headlamp Leveling Control - On vehicles so equipped, the right thumbwheel on the dimmer module is rotated to the 0, 1 or 2 detent positions to provide the appropriate resistor multiplexed output to the BCM over the headlamp leveling switch to module signal circuit. The BCM reads and responds to this input by providing the appropriate control outputs to the headlamp leveling motors.
- Interior Lighting Control - The left thumbwheel on the dimmer module is rotated to the dome DEFEAT, dome ON, PARADE mode, or one of the six panel dimmer detent positions to control the interior courtesy/dome and panel lamps. The dimmer module provides the appropriate resistor multiplexed output to the BCM over the panel lamps dimmer signal circuit. The BCM reads and responds to this input by providing the appropriate control outputs through internal HSDs over the courtesy lamps, panel lamps and reading lamps driver circuits, and by sending appropriate electronic dimming level messages to other electronic modules over the CAN data bus.

The dimmer module as well as the hard wired inputs and outputs of the module may be diagnosed using conventional diagnostic tools and procedures. Refer to the appropriate wiring information.