Headlamp: Description and Operation

Voltage is available at all times to the Headlamp Switch from the LIGHTING Maxi Fuse through the RED (42) wire. Within the Headlamp and Panel Dimmer Switch is a 17A circuit breaker which resets automatically. The circuit breaker opens upon heating due to an overcurrent condition. With the circuit breaker open, current stops and the circuit breaker's thermal element cools. When sufficiently cooled, the circuit breaker closes.

The three position Headlamp Switch has an OFF position, a PARKING LAMPS position, and a HEADLAMPS position. When the switch is in the HEADLAMPS position, voltage is available on the YEL (10) wire to the Headlamp Switch. The Headlamp Switch is part of the Multifunction Switch on the Steering Column. By pulling the MultiFunction Switch Lever up along the axis of the Steering Column, the switch changes selections. Repeated switch operations alternate between the high and the low beam selections.

With the low beams selected, voltage is available on the TAN (12) wire to the low beam connector pins or to the Low Beam Headlamps (composite). Because the Headlamps are grounded, current flows through the low beam filaments and light is emitted.
- The RH Headlamp is grounded at Ground G112 by BLK (250)
- The LH Low Beam Headlamp is grounded at Ground G113 BLK (150)
- The RH Low Beam Headlamp is grounded at Ground G112 by BLK (250)

With the light beams selected, voltage is available on the LT GRN (11) wires to the high beam connector pins or the the High Beam Headlamps (composite). Because the Headlamps are grounded, the lamps operate.
- The LH Headlamp is grounded at Ground G113 by BLK (150)
- The LH High Beam Headlamp is grounded at Ground G113 by BLK (150)
- The RH High Beam Headlamp is grounded at Ground G112 by BLK (250)

LT GRN (11) also makes high beam voltage available at the Instrument Cluster for lighting the blue Headlamp High Beam Indicator Lamp. Since the Instrument Cluster's lamp circuits are grounded at Grounds G103 or G104 by BLK (451), the lamp lights when voltage is available.