Principles of Operation

Parking, Rear and License Plate Lamps

Principles of Operation

The Steering Column Control Module (SCCM) monitors the headlamp switch position by sending voltage signals on multiple circuits to the headlamp switch. There is one circuit for each headlamp switch position. At any given time, one of the signal circuits is switched to ground. The SCCM (Steering Column Control Module) sends a message to the Body Control Module (BCM) over the High Speed Controller Area Network (HS-CAN), indicating the headlamp switch position.

When the BCM (Body Control Module) receives a network message from the SCCM (Steering Column Control Module) that the headlamp switch is in the PARKING LAMPS ON position, the BCM (Body Control Module) provides voltage to the parking lamps.

If the SCCM (Steering Column Control Module) does not detect any active inputs from the headlamp switch for 5 seconds, or if the SCCM (Steering Column Control Module) detects multiple headlamp switch input circuits are active, the SCCM (Steering Column Control Module) sends a message to the BCM (Body Control Module) to indicate the fault. The BCM (Body Control Module) then turns the parking lamps and headlamps on and keeps them on until the battery saver feature times out.

Refer to Exterior Lighting Exterior Lighting in the Description and Operation for information regarding the battery saver feature.

If either situation occurs, the SCCM (Steering Column Control Module) and the BCM (Body Control Module) cannot be ruled immediately as being at fault. This is normal behavior of the SCCM (Steering Column Control Module) and the BCM (Body Control Module) when a fault has been detected with the inputs from the headlamp switch.