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 overlay, 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 when the headlamp high beams are illuminated, or when the exterior lamps are inadvertently left ON. This indicator is controlled by a hard wired input from the headlamp beam select switch circuitry of the left multi-function switch to the cluster, and by the instrument cluster electronic circuit board based upon cluster programming and hard wired inputs from the head/park/fog lamp switch circuitry of the left multi-function switch, the driver door ajar switch, and the ignition switch. The high beam indicator bulb is grounded on the instrument cluster electronic circuit board at all times; therefore, the bulb will be illuminated anytime the headlamp high beams are turned on, regardless of the ignition switch position. The bulb only illuminates when it is provided battery current by the beam select switch circuitry of the left multi-function switch, or by the instrument cluster electronic circuit board. The instrument cluster will turn on the high beam indicator for the following reasons:

- Beam Select Switch Input - Each time the cluster detects battery current on the beam select switch sense circuit (beam select switch closed = high beams selected or optical horn feature activated) the high beam indicator will be illuminated solid. This input can occur when the headlamp high beams are selected or when the optical horn feature is activated. The indicator remains illuminated until the beam select switch sense input to the cluster is an open circuit (beam select switch open = high beams not selected and optical horn feature not activated), or until the exterior lighting is turned off; whichever occurs first.

- Exterior Lamps-ON Optical Warning - Each time the cluster detects battery current on the headlamp switch output circuit (park or head lamp switch closed = exterior lighting is ON), ground on the driver door ajar switch sense circuit (driver door ajar switch closed = driver door is open), and the fused ignition switch output (run-start) input is an open circuit (ignition switch is in a position other than ON or Start), the high beam indicator will be flashed ON and OFF repeatedly. The indicator will continue to flash until the exterior lighting is turned OFF, the driver door is closed, or the ignition switch is turned to the ON or Start positions, whichever occurs first.

- Actuator Test - Each time the cluster is put through the actuator test, the high beam indicator will be turned ON, then OFF again during the bulb check portion of the test to confirm the functionality of the bulb and the cluster control circuitry.

The headlamp beam select switch and circuitry is integral to the left multi-function switch on the steering column, and is connected in series between fused B(+) and the high beam indicator driver circuit input to the instrument cluster. The left multi-function switch inputs to the instrument cluster circuitry can be diagnosed using conventional diagnostic tools and methods.(Refer to ELECTRICAL/LAMPS/LIGHTING - EXTERIOR/LEFT MULTI-FUNCTION SWITCH - OPERATION). For further diagnosis of the high beam indicator or the instrument cluster circuitry that controls the indicator bulb, (Refer to ELECTRICAL/INSTRUMENT CLUSTER - DIAGNOSIS AND TESTING).