Hi-Beam Indicator Lamp: Description and Operation

A high beam indicator is standard equipment on all instrument clusters. The high beam indicator is located near the upper edge of the instrument cluster, between the tachometer and the speedometer. The high beam indicator consists of a stencil-like cutout of the International Control and Display Symbol icon for "High Beam" in the opaque layer of the instrument cluster overlay The dark outer layer of the overlay prevents the indicator from being clearly visible when it is not illuminated. A blue lens behind the cutout in the opaque layer of the overlay causes the icon to appear in blue through the translucent outer layer of the overlay when it is illuminated from behind by a replaceable incandescent bulb and bulb holder unit located on the instrument cluster electronic circuit board. The high beam indicator is serviced as a unit with the instrument cluster.

The high beam indicator gives an indication to the vehicle operator whenever the headlamp high beams are illuminated. This indicator is controlled on the instrument cluster circuit board based upon a hard wired high beam indicator driver circuit input received by the cluster from the Central Timer Module (CTM). The CTM monitors an input from the headlamp beam select switch circuitry integral to the multi-function switch on the left side of the steering column. The high beam indicator bulb receives battery current on the instrument cluster electronic circuit board through a fused B(+) circuit at all times; therefore, the indicator remains operational regardless of the ignition switch position. The indicator only illuminates when it is provided with a path to ground by the CTM. The high beam indicator may be diagnosed using conventional diagnostic tools and methods. For proper diagnosis of the CTM and the inputs to the CTM that control the high beam indicator driver circuit, a DRBIII scan tool is required. Refer to the appropriate diagnostic information.