Exterior Lighting - System Operation and Component Description: Led

Headlamps - LED 

System Diagram 

Courtesy of FORD MOTOR COMPANY

Network Message Chart 

BCM Network Input Messages 

GWM Network Input Messages 

HCM Network Input Messages 

Low Beams 

The BCM 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 to indicate the headlamp switch position.

The BCM turns the parking lamps and headlamps on when the ignition is in ON 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 ignition is in ON, the BCM supplies voltage to the LED control module attached to each headlamp assembly through the low beam headlamp circuit. This LED control module is used to control the low beam Light Emitting Diodes (LEDs).

When the BCM receives a request to turn the headlamps on, it sends a low beam message over the HS-CAN1 to the HCM. The HCM sends the low beam message over the LIN circuit to the LED control module attached to each headlamp assembly to illuminate the low beam Light Emitting Diodes (LEDs).

During low beam operation, the low beam Light Emitting Diodes (LEDs) illuminate through the headlamp assembly projector lens.

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 message requesting the high beams, it sends a high beam message over the HS-CAN1 to the HCM. The HCM sends the high beam message over the LIN circuit to the LED control module attached to each headlamp assembly to illuminate the high beam LED in addition to the low beam Light Emitting Diodes (LEDs). This changes the headlamp beam brightness to illuminate a greater distance.

When the ignition is in ON, the BCM supplies voltage to the LED control module attached to each headlamp assembly through the high beam headlamp circuit. This LED control module is used to control the high beam LED.

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 an interior rear view mirror mounted camera to monitor surrounding traffic conditions and high beam usage. The camera is hardwired to the IPMA and serviced as an assembly. 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 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 multifunction switch is placed in the flash-to-pass position again.
• the ignition switches to RUN.

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

Signature Lighting 

When the ignition is in ON, the BCM supplies voltage to the LED control module attached to each headlamp assembly. This module is used to control the signature/park lamps.

The signature/park lamps illuminate when the following is true:

• the headlamp switch is in the AUTOLAMPS position
• the ambient light sensor receives enough light that the headlamps are not commanded on
• the DRL are configured on

When the BCM receives a message requesting the parking lamps on, it sends a message over the LIN circuit to the LED control module attached to each headlamp assembly to reduce the intensity of the signature/park lamp Light Emitting Diodes (LEDs).

When the parking lamps are off, the signature/park lamp Light Emitting Diodes (LEDs) illuminate at full intensity.

When the BCM sends a RH or LH turn message through the LIN circuit to the LED control modules, the corresponding signature/park lamp is turned off while the turn signal is active. When the turn signal is no longer active, the daytime signature/park lamp once again illuminates.

Automatic Headlamp Leveling - Except North America 

The headlamp beam height will be automatically adjusted according to vehicle load, speed, acceleration and braking data received from the ABS module, PCM and the vehicle height sensors.

The front lighting uses the HCM to command the up/down aiming of the headlamps through the LIN to the headlamp assemblies. The headlamp assemblies contain a module that receive the messages through the LIN from the HCM.

Depending on the inputs received (steering wheel angle and vehicle speed for example), the HCM can command the height at which the headlamps are aimed (up or down) to improve nighttime visibility. Automatic headlamp leveling is activated when the headlamp switch is in the HEADLAMPS or AUTOLAMPS position.