Principles of Operation

WARNING: This page is about a different car, the 2013 Ford F-550 Super Duty, 2013 Ford F-450 Super Duty, 2013 Ford F-350 Super Duty, and 2013 Ford F-250 Super Duty. However, it is still accessible from the selected car via links, so may be relevant.

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 sends a message over the High Speed Controller Area Network (HS-CAN) to the Body Control Module (BCM) to indicate the headlamp switch position.

If the SCCM does not detect any active inputs from the headlamp switch for 5 seconds, or if the SCCM detects multiple headlamp switch input circuits short to ground, the SCCM sends a message to the BCM to indicate the fault. The BCM then 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 for information regarding the Battery Saver feature.

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

When the BCM receives a network message from the SCCM that the headlamp switch is in the PARKING LAMPS ON position, the BCM provides voltage to the parking lamps.