Dimmer Switch - Operation

OPERATION

The dimmer module uses a single resistor multiplexed output to control the many functions and features it provides. The switch receives a clean ground from the ElectroMechanical Instrument Cluster (EMIC) (also known as the Cab Compartment Node/CCN) on a multifunction switch MUX return circuit. It then provides outputs to the EMIC on a panel lamps dimmer signal circuit to control panel dimmer and interior lighting functions.

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 EMIC on a panel lamps driver circuit. The EMIC controls this output based upon the panel lamps dimmer signal circuit input from the dimmer module.

The dimmer module operates as follows:

- 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 EMIC over the panel lamps dimmer signal circuit. The EMIC 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.