Low Beams

WARNING: This page is about a different car, the 2013 Ford Explorer. However, it is still accessible from the selected car via links, so may be relevant.

The headlamp switch is integrated into the FLM . The FLM monitors the headlamp switch position and sends a headlamp switch status message over the communication network to the 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 HEADLAMPS , Battery Saver). 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 headlamps on, it supplies voltage to the headlamp bulbs (halogen headlamps) or the ballasts (HID headlamps) within each headlamp assembly.

Vehicles with halogen headlamps use single filament bulbs.

Vehicles with HID headlamps utilize ballasts to provide the necessary voltage to illuminate the HID bulbs.

The BCM also provides an overload protection of the low beam output circuits. When an excessive current draw is detected, the BCM disables the affected low beam circuit driver. REFER to FIELD EFFECT TRANSISTOR (FET) PROTECTION .