Cluster Illumination

The instrument cluster has several Light Emitting Diode (LED) units that provide cluster back lighting whenever the exterior lighting is turned ON. The illumination intensity of these LED units is adjusted when the panel lamps dimmer function of the thumbwheel on the headlamp switch is rotated to one of six available minor detent positions. The CCN monitors a hard-wired multiplexed input received from the headlamp switch on the instrument panel to determine the selected lighting level. In response to that input, the CCN electronic circuitry converts a fused 12-volt input it receives on a hard-wired panel lamps dimmer switch signal circuit into a 12-volt Pulse Width Modulated (PWM) output.

The CCN uses this PWM output to control the illumination intensity of the cluster general illumination lighting and the VFD units on the CCN circuit board, then provides a synchronized PWM output on various hard-wired fused panel lamps dimmer switch signal circuits to control and synchronize the illumination intensity of other incandescent illumination lamps in the vehicle. The CCN also transmits electronic dimming level  messages over the CAN and LIN data bus to other electronic modules in the vehicle to control and synchronize the illumination intensity of their display units to that of the CCN displays.

The hard-wired panel lamps dimmer outputs from the CCN may be diagnosed using conventional diagnostic tools and procedures. However, proper testing of the PWM processing of the CCN and the electronic dimming level  messages received by the CCN over the LIN data bus requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information.