The instrument panel dimming system operates to provide a variable level of illumination at the speedometer and control switches. By adjusting the position of the dimmer control on the IP Cluster, a variable voltage is supplied to the system lamps and components.

Voltage is available at all times at circuit breaker 19. This voltage is supplied to the taillamp relay coil through CKT 93 (GRN). When the headlamp switch is positioned in either the PARK or ON positions, this switch supplies a ground to the taillamp relay coil. The taillamp relay then closes the normally open (87) contact, supplying power to the panel lamps and the IP dimmer switch. Ground is supplied through a variable resistance in the dimmer control. The resistance depends upon the position of the dimmer control.

The variable resistance ground is fed to the lamps from CKT 3 (BLK/RED) through joint connector #3. The joint connector is like a large splice pack. The joint connector distributes the variable resistance ground to the system lamps by CKT 40, CKT 173, CKT 134, CKT 124, CKT 86, CKT 116, CKT 146, CKT 104, CKT 39, CKT 100, CKT 353, CKT 46 or CKT  165 (BLK/RED).