The device and principle of operation of the light sensor in the car

Additional functions in modern vehicles make driving more comfortable and safer. One of these options is a car light sensor. In the article we will tell you about its structure and how it works.

What is a light sensor in a car

Another name for this option is light sensor. Its structure is quite simple. It is a photocell, control unit and a small relay. The element itself is installed in the most illuminated place of the car, which is not subject to contamination. Usually above or below the windshield. Indirectly, the light sensor can be attributed to security systems. The driver may simply forget or ignore the need to turn on the headlights when entering a tunnel or other darkened area. The system will do it itself.

A photocell detects changes in illumination in space. If there is not enough light, a signal is transmitted to the control unit, and then the relay turns on the dipped beam and side lights. If the system detects sufficient illumination, then the lighting is turned off.

Light sensor device

The design of the component and the entire system is fairly simple. If such an option is present in the basic configuration of the car, then it is located in a special recess in front of the windshield. The sensor housing contains an LED and light-sensitive elements. The sensor is connected to the control unit, relay and contacts for switching on the dimensions and dipped beam.

The light control switch must be set to AUTO for the system to work in automatic mode.

Special photodiode filters detect daylight and electric light. It is very convenient, for example, when entering a tunnel or covered parking. You can also adjust the time for the headlights to dim after the ignition is turned off or under normal lighting conditions.

Types of light sensors

Conventional light sensor

If the car is not equipped with such a device, then it can be easily installed by yourself. The system is inexpensive. It is enough to fix the sensor, connect the relay and correctly connect the wires to the car wiring. The system will work properly.

Built-in light sensor

Built-in light control components come in more expensive trim levels. As a rule, the set of their functions is wider. You can configure the system to turn on the interior light, turn on and off the dashboard lights.

Combined light sensor

Often a light sensor can be combined with a rain sensor in one device. In this case, it is attached to the top of the windshield. If everything is clear with the light sensor, then the operation of the rain sensor is also based on photodiodes and photocells. If raindrops fall on the windshield, the transmitted light is refracted differently and scattered on the way back. Photocells catch this and turn on the windshield wipers. In heavy rain, the headlights also turn on automatically. Drivers note that the system is working correctly and correctly. The driver does not need to turn on the wipers every time the glass gets wet. A photocell detects the water level on the glass and the intensity of rain and adjusts the frequency of the wipers on its own. On some models, the glass is heated when it rains to prevent it from misting up.

How to check if the device is working

This option is very convenient and drivers get used to it quickly. No need to worry about turning the headlights on or off - the system does it by itself. But if the system fails, then the motorist may not notice the breakdown in time.

It is very easy to check the light sensor. It is enough to cover it with dark material or rags. If everything is in order, then the system will perceive it as night and turn on the lights and side lights.