Dimming

The instrument cluster controls all of the interior dimming functions. The instrument cluster receives an ambient light level input from the ambient light sensor and determines whether it is light or dark. If the ambient light sensor is inoperative, the instrument cluster will assume a condition of darkness. Dimming of the VF displays is only allowed when the ignition switch is in the RUN position, the park lamps are on, and the ambient light sensor indicates darkness. If all conditions for the VF dimming are met, the instrument cluster uses the input from the potentiometer in the headlamp switch to determine the level of dimming. The dimming level is sent to the radio (IRC), the cellular telephone (PHN), and the HVAC control module by a Class 2 message. The IRC and the PHN then adjust the dimming level of their VF display. The instrument cluster provides a 54 volt supply to the HVAC control module for its VF display. The instrument cluster provides dimming control of the incandescent lighting through the INC DIM 1 and INC DIM 2 outputs. The instrument cluster provides dimming control of the electronic PRNDL LED through the LED dimming signal circuit. The dimming level will vary based on the potentiometer in the headlamp switch when the park lamps are on and the ambient light sensor indicates darkness, regardless of the position of the ignition switch.