Active headlights

Active headlights are an intelligent headlight system that optimizes illumination of the road surface at night by turning out the light beam. The motorized headlights are controlled by the headlight control module (HCM), which retrieves signals from the CAN network.

In order to activate the active headlight function, the headlight control module (HCM) (4/118) needs information on the following: vehicle speed, current gear, light conditions.

The headlight control module (HCM) receives information from the following control modules: 

• Brake control module (BCM) (4/16) for information on vehicle speed
• Transmission control module (TCM) (4/28) for information on current gear (automatic transmission)
• Central electronic module (CEM) (4/56) for information from the reversing light switch (3/10) (manual transmission)
• Central electronic module (CEM) for information from the twilight sensor (7/12)

The headlight control module (HCM) is activated automatically when the ignition switch is turned to position II. In order to turn out the light beam, the following conditions must be fulfilled:

• The vehicle must be in motion, that is to say travelling at a speed greater than 3.6 km/h (2.2 mph).
• Reverse gear must not be engaged.
• No daylight light conditions.

The switch for active headlights on the climate control module (CCM) (3/112) can be used to disable/enable the function.

When the function is active, the headlight control module (HCM) receives continual information on vehicle speed and steering angle. Vehicle speed is obtained from the brake control module (BCM) while steering angle information comes from the steering wheel angle sensor module (SAS) (3/254). This information enables the headlight control module (HCM) to calculate the current turn-out of the light beam.