Daytime Running Lamp: Description and Operation

DAYTIME RUNNING LAMPS (DRL)

The ambient light sensor is a light sensitive transistor that varies its signal to the body control module (BCM) in response to changes in the outside ambient light level. Any function or condition that turns ON the headlamps will cancel daytime running lamp (DRL) operation. With the headlamp switch in the OFF position, activating automatic lamp control (ALC), the front turn signal lamps will be turned ON after a 30-second delay under daylight conditions, which is determined by the ambient light sensor signal to the BCM. The DRL operates when the ignition switch is in the RUN position, the front wipers are not activated, and the transmission is not in PARK. When these conditions have been met and the ambient light sensor indicates daylight conditions, the BCM will illuminate the front turn signal lamps ON steady.