High Beam Headlamps
WARNING: This page is about a different car, the 2022 Cadillac CT4. However, it is still accessible from the selected car via links, so may be relevant.
When the low beam headlamps are ON and the turn signal/multifunction switch is placed in the high beam position, ground is applied to the BCM through the high beam signal circuit. The BCM responds to the input by sending a serial data message to the Lighting Control Module. The Lighting Control Module then sends a pulse width modulated voltage signal to the headlamp assembly. The headlamp assembly responds by illuminating the respective high beam LEDs.
High Beam Indicator
The status of the high beam lamps is shown by a blue indicator located on the instrument cluster. When high beams are commanded, the indicator will be illuminated continuously. If the driver turns off the high beams, the indicator will turn off.