Principles of Operation
WARNING: This page is about a different car, the 2013 Ford F-150. However, it is still accessible from the selected car via links, so may be relevant.
The Body Control Module (BCM) controls the Daytime Running Lamps (DRL) by using various inputs to determine whether or not the DRL should be illuminated. These inputs include:
- Ignition status
- Headlamp switch position
- Headlamps on or off
- Transmission gear selection
If equipped with halogen headlamps, when the DRL is active, the BCM provides a pulse-width modulated voltage to the low beam headlamps. This illuminates the headlamps at a reduced intensity.
If equipped with HID headlamps, when the DRL is active, the BCM provides voltage to the front turn lamps.
The DRL is a programmable parameter for this vehicle.