Headlamps - Halogen Headlamps

System Diagram 

Courtesy of FORD MOTOR CO.

Network Message Chart 

BCM Network Input Messages 

Low Beams 

The headlamp switch sends a status message over the LIN circuit to the BCM to indicate the headlamp switch status (position or a fault with the headlamp switch). The BCM turns the parking lamps and headlamps on when the ignition is in RUN and the BCM detects a fault from the headlamp switch or wiring. This is normal behavior of the BCM when a fault has been detected with the inputs from the headlamp switch.

When the BCM reads a request for the headlamps on, it supplies voltage to the headlamp low beam bulb within each headlamp assembly.

The BCM also provides Field Effect Transistor (FET) protection of the low beam output circuits. When an excessive current draw is detected, the BCM disables the affected circuit driver.

High Beams 

The SCCM monitors the LH steering column multifunction switch for a high beam request. When the LH steering column multifunction switch is in the HIGH BEAMS position, the SCCM sends a message over the HS-CAN2 to the GWM, then the GWM sends the message to the BCM over the HS-CAN1.

When the BCM receives a request for high beams, it supplies voltage to the headlamp high beam bulb within each headlamp assembly.

The BCM also provides Field Effect Transistor (FET) protection of the exterior lamps switched voltage and high beam output circuits. When an excessive current draw is detected, the BCM disables the affected circuit driver.

Automatic High Beams 

The automatic high beam system uses a camera to monitor surrounding traffic conditions and high beam usage. The camera is part of the IPMA. The IPMA communicates light information over the HS-CAN2 to the GWM then the GWM sends the information to the BCM over the HS-CAN1.

The automatic high beam feature is active only when the headlamp switch is in the AUTOLAMPS position.

During nighttime driving, the automatic high beam system automatically turns the high beams on if it is dark enough and no other traffic is present. When the system detects an approaching vehicle's headlamps or a preceding vehicle's rear lamps, the system turns off the high beams. When the approaching vehicle's headlamps or the preceding vehicle's rear lamps are no longer detected, the high beams automatically turn back on.

The IPMA turns the high beam headlamps on when the following conditions are met: 

• The feature has been enabled using the message center
• The headlamp switch is in the AUTOLAMPS position and the autolamps feature has turned the exterior lamps on
• The vehicle speed is greater than 51 km/h (32 mph)
• The IPMA determines the ambient lighting conditions are dark enough
• The IPMA does not detect any light source that can be interpreted as an illuminated vehicle lamp

The IPMA turns the high beams off if any of the following occur: 

• The IPMA detects any light source that can be interpreted as an illuminated vehicle lamp
• The IPMA determines the ambient lighting conditions are not dark enough
• The vehicle speed falls below 44 km/h (27 mph)
• The autolamps are turned off
• The IPMA determines the view is blocked

Flash-To-Pass 

The SCCM monitors the LH steering column multifunction switch for a flash-to-pass request. When the LH steering column multifunction switch is in the FLASH-TO-PASS position, the SCCM sends a message over the HS-CAN2 to the GWM then the GWM sends the message to the BCM over the HS-CAN1.

When the ignition is in RUN and the flash-to-pass is requested, the high beams are activated as long as the LH steering column multifunction switch is held in the flash-to-pass position.

Headlamp Exit Delay 

When the ignition is OFF and the LH steering column multifunction switch is placed in the FLASH-TO-PASS position and released, the parking lamps and low beams are illuminated. They remain illuminated until:

• 3 minutes have elapsed with a door open.
• 30 seconds have elapsed after all doors are closed.
• the LH steering column multifunction switch is placed in the flash-to-pass position again.
• the ignition switches to RUN.

Within the 30 second delay and all the doors closed, opening any door results in the 3 minute timer restarting.