Circuit/System Description
WARNING: This page is about a different car, the 2022 Cadillac CT5. However, it is still accessible from the selected car via links, so may be relevant.
The following conditions must be met for the rear fog lamps to illuminate:
- Ignition ON, vehicle running
- The turn signal/multifunction switch is in the AUTO or Headlamps ON position
- The rear fog lamps, low beams or high beams must be ON.
The rear fog lamp switch signal circuit is grounded momentarily by pressing the rear fog lamp switch on the turn signal/multifunction switch. The BCM responds by sending a serial data message to the Lighting Control Module. The Lighting Control Module responds by applying voltage to the rear fog lamp control circuit which illuminates the rear fog lamp LED. The park lamps are automatically commanded ON whenever the rear fog lamp switch is commanded ON.