Function of Car Headlights, Circuit, and Its Components

To ensure safety in driving a car, every car manufacturer has equipped cars with lights as a lighting system. The light components serve to illuminate dark roads, improve visibility during heavy rain, or signal to other drivers. Within the car's lighting system, there are various lights, including headlights. 

So what is the function of headlights in the car's lighting system? How are they wired, and what components are included? For more details, see the review below.

Function of Car Headlights

Here are some functions of headlights in the car's lighting system:

1. As the front car lighting.
2. As high beam lights. This makes it easier for drivers to see road conditions from a distance (high beam), especially when the road is dark or during heavy rain.
3. As low beam lights.

Read Also: Types of Car Light Sockets and Their Functions, Let's Understand!

Headlight Wiring in Cars

Here are some electrical wiring examples for car headlights that you can refer to.

1. Standard or Manual Headlight

In this wiring, the headlights will turn on when you press the light switch. Here is the complete flow:

• When the low beam switch is pressed, the battery supplies electric current to the relay.
• The electric current in the relay will be split into two. For the first current, the electric flow will pass through the fuse to terminal 30 on the relay. Meanwhile, the second current serves as a control current in terminal 85 on the relay.
• The presence of the low beam switch located at terminal 86 also connects terminal 30 and 87, so the lights will automatically turn on.
• When you turn on the high beam switch, the electric flow will change from low beam to high beam.
• At the same time, the electric flow from the battery also enters relay 87 and 30 for high beam. This condition causes the high beam lights to turn on quickly because the headlights are supplied with electric current from terminal 87.

In the standard headlight wiring, it is not influenced by the ignition key position. Even in the OFF position, the lights can still turn on.

2. Semi Auto Headlight

In this wiring, it is almost similar to the manual headlight wiring. However, there is a slight difference in that the auto headlight switch comes from the output of the low beam relay, specifically terminal 86, which is connected in parallel. When the ignition key is in the ON position, the electric current automatically flows to the collector and emitter legs, causing the low beam lights to turn on.

Components of Headlight Wiring

Below are some components found in the car headlight wiring, including:

1. Battery or Accumulator

This component serves as the power supply for the car's electrical system, including the lighting system.

2. Headlight Wiring Harness

This component serves as the conductor for the electric flow from the battery. The wires will be arranged according to the required wiring diagram.

3. Fuse

The fuse component serves to protect against short circuits in the electrical system.

4. Main Switch

This component acts as the main switch that functions to break and connect the electric current from the battery to the combination switch or dimmer switch.

5. Combination Switch

This component serves to turn off, turn on the lights, and separate the circuits for low beam and high beam lights. 

6. Relay

A protective component for the combination switch.

Read Also: What is a Relay in a Car? Here are Its Functions & How It Works

7. High Beam Light

A light that uses 60 to 100 W of power, functioning as a high beam light.

8. Low Beam Light

A low beam light equipped with an electric power of 90W or 55 W.

If you need assistance in wiring your car's headlights, you can take your car to the nearest Daihatsu dealer for proper installation.