Hi-Beam Indicator Lamp: Description and Operation

HIGH BEAM INDICATOR

DESCRIPTION
A high beam indicator is standard equipment on all instrument clusters. The high beam indicator is located near the lower edge of the instrument cluster, to the left of the multi-function indicator display. The high beam indicator consists of the International Control and Display Symbol icon for "High Beam" imprinted within a rectangular cutout 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 Light Emitting Diode (LED) behind the cutout in the opaque layer of the overlay causes the icon to appear silhouetted against a blue field through the translucent outer layer of the overlay when the indicator is illuminated from behind by the LED, which is soldered onto the instrument cluster electronic circuit board. The high beam indicator is serviced as a unit with the instrument cluster.

OPERATION
The high beam indicator gives an indication to the vehicle operator whenever the headlamp high beams are illuminated. This indicator is controlled by a transistor on the instrument cluster circuit board based upon cluster programming and a hard wired input from the multi-function switch. The high beam indicator Light Emitting Diode (LED) is completely controlled by the instrument cluster logic circuit, and that logic will allow this indicator to operate whenever the instrument cluster receives battery current on the fused B(+) circuit. Therefore, the LED can be illuminated regardless of the ignition switch position. The LED only illuminates when it is provided a path to ground by the instrument cluster transistor. The instrument cluster will turn on the high beam indicator for the following reasons:

- Bulb Test - Each time the ignition switch is turned to the On position the high beam indicator is illuminated by the cluster for about two seconds as a bulb test.
- High Beams On Input - Each time the cluster receives a high beam headlamps-on input from the multi-function switch, the high beam indicator will be illuminated. The indicator remains illuminated until the cluster receives a high beam headlamps-off input from the multi-function switch.

The instrument cluster continually monitors the multi-function switch input to determine whether the high beam indicator should be illuminated or extinguished. The multi-function switch and the multifunction switch input circuit to the instrument cluster can be diagnosed using conventional diagnostic tools and methods. For proper diagnosis of the instrument cluster circuitry that controls the high beam indicator, a diagnostic scan tool is required. Refer to the appropriate diagnostic information.