When the ignition switch is turned to the ON position, the dash integration module (DIM) sends a class 2 message to the instrument panel integration module (IPM), the instrument cluster, and the radio. In response to this message, each module will turn on its vacuum fluorescent (VF) displays at maximum brightness. The IPM turns on the VF display for the heater and A/C control head.

When the park lamps are turned on, battery positive voltage (B+) is supplied to the dash integration module (DIM) dimming circuit from the rear fuse block DIMR Fuse. The DIM also sends a class 2 message to the IPM, indicating that the park lamps are on. The IP dimmer switch in the headlamp switch is supplied a reference voltage (5 V) and ground from the IPM. The switch is a potentiometer that varies resistance as the switch is moved. The IPM receives an input voltage proportional to the resistance of the potentiometer.

When the park lamps are on and it is dark outside, the IPM sends a class 2 message to the DIM, the instrument cluster, the door modules, and the radio indicating that the VF displays and incandescent lamps should be dimmed and the dimming level. The IPM, the instrument cluster, and the radio all dim their VF displays to match the current dimming level. The DIM sends a pulse width modulated (PWM) signal to the IP and console incandescent switch backlighting at the dimming level indicated by the IP dimmer switch. Each door module also sends a PWM signal to the incandescent switch backlighting in the respective door at the dimming level indicated by the class 2 message which was sent by the IPM.

When the IP dimmer switch is moved from MIN to MAX, all VF displays and incandescent switch backlighting dimming level changes from minimum intensity to maximum brightness in response to the IP dimmer switch.

The instrument cluster provides a 54 volt supply to the instrument panel integration module (IPM). The supply circuit is used to power the HVAC vacuum fluorescent (VF) display.