Why does the Mercedes-Benz daytime headlight turn on automatically?
3 Answers
Mercedes-Benz headlights are set to automatic by default. When the automatic headlights turn on, it indicates that the ambient light is dim and requires illumination. Automatic headlights function by sensing changes in external light intensity to control the automatic activation or deactivation of the headlights. Below are relevant details: 1. Sensor: Automatic headlights rely solely on a sunlight sensor to determine the surrounding brightness and cannot analyze real-time changes in the environment to select between high and low beams. If you want the automatic headlights to control the high beams, you need to push the combination light switch forward to the high beam position. 2. Automatic Headlights: Also known as auto headlights, these are systems installed by some manufacturers for driver convenience, featuring a photosensitive control system in the headlights. When this system detects that the external light intensity is above or below a certain threshold, the car's headlights will automatically turn on or off.
Mercedes-Benz's automatic daytime lights are actually for safety considerations. EU regulations require all new cars to be equipped with daytime running lights, and Mercedes has globalized this standard. Once when I drove a friend's GLC into a tunnel, the lights instantly brightening really woke me up. These constantly-on lights are actually specialized LED daytime running lights, consuming only a fraction of the electricity of regular bulbs—even more power-efficient than charging a phone. Nowadays, many cars also add tear-shaped light strips to the grille, making a Mercedes recognizable from 300 meters away during the day and improving visibility for oncoming traffic. However, if you really don't want them on, you can disable the automatic mode in the central control's lighting settings, though it's not recommended.
The green headlight indicator on the dashboard is the reason. Mercedes' light sensor is quite sensitive, even tree shadows can trigger the headlights. I've observed the new C-Class - on cloudy days the sensor automatically switches between low beams and daytime running lights. For rainy days, I recommend just keeping it in auto mode - the rear fog lights will activate automatically based on rainfall intensity, which is much safer than manual operation. This feature is particularly useful in North America, allowing full concentration when driving through underpasses. Newer models even integrate with navigation - the lights illuminate 0.5 seconds before entering tunnels.
