The backlighting is controlled by the cluster photocell, which senses the light inside of the car and brightens or dims the cluster's four halogen bulbs. These number 882 halogen bulbs are replaceable on the 1984-1988 clusters. The 1989 cluster uses a Xenon bulb, which is also replaceable. The 1984-1988 cluster's bulbs are rated at 3.8 candlelight power and the average life is estimated between 1,500-3,000 hours of continuous use.
     When the parking lights are turned on the cluster goes into a photo cell over-ride and a limited dimming control is obtained by turning the head light switch knob. The 1984-1989 clusters have one 32-pin connector (Fig. 1) and one 24-pin connector (Fig. 2).
     The 32-pin connector is used for power, grounds, sensor signals and output signals. The 24-pin connector is used for driver information switch input signals. The large connector contains the ignition-on signal's 12 volts, constant power for microprocessor memory and grounds going to the chassis and engine. Cavity D1 is a black ground wire going to the IP harness wire to the IP ground at the left dash at the door