Headlamps

Battery positive voltage (B+) is supplied at all times through the LH underhood fuse block LCM/HDLP circuit breaker via CKT 242 (RED) to the following components:
^ Headlamp switch
^ Lamp control module (LCM)

When the headlamp switch is placed in the ON position, battery positive voltage (B+) is supplied via CKT 10 (YEL) to the headlamp dimmer switch. When the headlamp dimmer switch is placed in the LOW position, battery positive voltage (B+) is supplied via CKT 12 (TAN) to the following components:
^ Left low beam headlamp
^ Right low beam headlamp

When the headlamp dimmer switch is in the HIGH position, battery positive voltage (B+) is supplied via CKT 11 (LT GRN) to the following components:
^ Left high beam headlamp
^ Right high beam headlamp

The LCM provides battery positive voltage (B+) via CKT 12 (TAN) to the headlamps under the following conditions:
^ The ignition switch is in the RUN position.
^ The ambient light sensor indicates darkness.

When equipped with lamp monitoring, the headlamp battery positive voltage (B+) feeds pass through the adaptive lamp monitor control module to the headlamps. The low beam headlamps receive battery positive voltage (B+) through CKT 1312 (TAN or TAN/WHT). The high beam headlamps receive battery positive voltage (B+) through CKT 1311 (LT GRN, LT GRN/BLK or LT GRN/WHT).

The lamp control module (LCM) monitors the ambient light conditions through the ambient light sensor. The ambient light sensor is a variable resistor whose resistance changes as the surrounding ambient light level changes. As the ambient light decreases, the resistance of the ambient light sensor increases. The LCM measures the resistance across the ambient light sensor and determines whether it is day or night.