Active Headlights

Courtesy of VOLVO CARS CORPORATION

Active headlamps are an intelligent headlamps system that optimizes lighting of the road surface at night by expanding the light beam. The motorized headlamps are controlled by the headlamp control module (HCM), which retrieves signals from the CAN network and, in some cases, from directly connected sensors.

For the active headlamp function to be enabled, the headlamp control module (HCM) (4/118) requires information on the following: vehicle speed, current gear, light conditions and steering angle.

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) (4/56) for information from the twilight sensor (7/12)
• Steering wheel angle sensor (SAS) (3/130) for information on steering angle

The active headlamp function is only enabled if the following conditions are met:

• 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.

Also, the function active headlamp must be activated. The function en active headlamp is deactivated/activated via the menu system in Infotainment control module (ICM) (3/281).

When the function is active, the headlamp 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) (3/130). This information enables the headlamp control module (HCM) to calculate the current turn-out of the light beam.