Daytime Running Lamps (DRL) with HID RPO T4F/T95

WARNING: This page is about a different car, the 2019 Buick Cascada, 2018 Buick Cascada, and 2017 Buick Cascada. However, it is still accessible from the selected car via links, so may be relevant.

The daytime running lights are LEDs which are continuously illuminated when:

Ignition is switched ON.
Engine is running.
High and low beam headlamps are ON or OFF.
Headlamp switch is in PARKING LIGHT, AUTOMATIC LIGHT or LOW BEAM position.

By turning the headlamp switch in the OFF position the automatic light function and the daytime running lamps will be deactivated.

The rain/ambient light sensor module is used to monitor outside lighting conditions. The rain/ambient light sensor module provides a serial data message to the body control module (BCM) based on outside lighting conditions to determine if outside lighting conditions are correct for either daytime running lights or automatic lamp control when the headlamp switch is in the AUTO position. In daylight conditions the BCM will command the designated daytime running lights ON. During low light conditions the BCM will command the low beam headlamps ON. Any function or condition that turns on the headlamps will cancel daytime running lights operation.