Daytime Running Lamp: Description and Operation

DAYTIME RUNNING LAMPS (DRL)

The Daytime Running Lamps (DRL) illuminate the low beam headlights at a reduced intensity. With the headlamp switch placed in the OFF position, the DRLs will operate when the ignition switch is in the RUN position, the gear selector is not in the PARK position and the parking brake is released. Any function that turns on the headlights will cancel DRL operation. DRL operation in Manual Transmission equipped vehicles will occur when the ignition switch is in the RUN position, and the parking brake is released.

In DRL operation, battery voltage is provided to the low beam filaments through the normally open contacts of the DRL relay and the voltage dropping diode circuit. When the ignition is in the RUN position, voltage is applied to the DRL relay and the DRL module. If the parking brake is applied, the DRL module will de-energize and open the relay contacts thus turning off the DRLs. Also momentarily when the engine is started, the DRL relay will de-energize and turn off the DRLs until the engine is started and running. The low beam filaments will operate at 90 percent intensity because of the additional voltage drop across the DRL dropping diode.