Principles of Operation

The headlamp switch is integrated into the Front Lighting Control Module (FLM). The FLM  monitors the headlamp switch position and sends a message over the High Speed Controller Area Network (HS-CAN) to the Body Control Module (BCM) to indicate the headlamp switch status (position or a fault with the headlamp switch).

If the BCM  detects a fault from the headlamp switch or loses communication with the FLM  , the BCM  turns the parking lamps and headlamps on and keeps them on until the battery saver feature times out.

Refer to EXTERIOR LIGHTING  in the Description and Operation portion of this section for information regarding the battery saver feature.

If either situation occurs, the BCM cannot  be ruled immediately as being at fault. This is normal behavior of the BCM  design as a fault has been detected with the inputs from the headlamp switch.

When the BCM  receives input requesting the parking lamps on, it energizes an internal relay to provide voltage to the parking lamps.