Automotive Maintenance And Detailing


Automotive Maintenance And Detailing

How does car horn work ?.

How does  car horn work? There is a simple answer to this question.

Almost all vehicles are equipped with horns to signal or warn people to be aware of their arrival, such as cars, trucks, motorcycles, trains, boats, except planes.

Usually, cars have equipped with horns because of the law. If your car horn broke, you must repair it. If the police ask for an inspection, you will be guilty of failing to maintain your car’s equipment ready for use.

Horns in cars and vehicles have a similar working principle. Most horns are operated electrically via a diaphragm and built-in induction coil. The complete system operation will make the horn sound in use.

 If there is no sound in the horn, you may have it repaired or replaced. We’ll cover how to do this in the next section.

What are the components of a car horn ?.

Today’s car horns function just as they were in cars a hundred years ago. What may change is the horn. Cars have different sounds, for example, a small car or a budget car have a beep sound. Expensive or large vehicles may have softer and louder bass.

The train horns also sound different and quite loud due to the loud noise of the diesel engine.

No matter how noisy they are, they work similarly.

Horn is mostly round shape, black.  It installs on the front of the car, such as behind the bumper, in front of a radiator, or in the wheel arch.   It depends on the vehicle’s make and design.

The circular housing of the horn is equipped with an induction coil behind it, and it has a diaphragm on the front.     When you press the horn at the steering wheel, the electric current will flow through the fuse and relay to the induction coil. The induction coil behind the horn will pull the diaphragm back and release it rapidly bounce back, and pull it again as long as the hand is pressing the steering wheel horn switch.

The rapid movement of the diaphragm creates a high-frequency movement of air and causes a sound to pass through the front cavity of the horn, creating a continuous sound that you can hear.

A) When the electric current is switched on, it crosses the contact breaker and enters the electromagnet, creating an electromagnetic field that moves the mobile part (whose two metal parts attract). B) The movement of the mobile part opens the circuit at the contact breaker, which closes itself due to electric attraction, taking the mobile part along and thus starting a new cycle.

From this picture, you will understand the principle of operation of the horn.

Horn shapes vary by make and model.


As in the below picture, it is a typical horn.

Typical car horn

The second picture is a dual tone horns with soft bass sound.  These horns have the shape like a square speaker’s mouth. Usually, two units mounted in pairs, and they will have a slightly different sound.

The horn has a sound level that exceeds 100 decibels. It is loud enough to use as a warning sound to other pedestrians or drivers.

Dual tone car horn

How to check and repair the car horn ?.

In general, the use of horns.  The car is one of the etiquettes of driving. Drivers in some countries press the horn frequently to warn other pedestrians or drivers. Meanwhile, some other countries may not use the horn unnecessarily if this is not the case.


If you use the horn frequently, it is easy to find the fault.


The horn does not work, or there is no sound when pressed, it can check with ease even if you are not a mechanic.


The components that you should check when the horn broke are

  1. Fuse
  2. Relay
  3. Horn wires
  4. Horn

Inspection process

  1. The fuse has blown or not. For the preliminary check, you need to have the owner’s manual. In the manual, descriptions and illustrations are showing the location and specification of the horn fuses. You should check if the fuse is blown or not.
  1. Is the relay broken? The relay is an essential part of the horn system. It mounted in the fuse and relay box, mostly in the engine compartment. Some vehicles may install a relay in the fuse box in the passenger compartment.

Most cars often have more than one relay of the same type installed on the same circuit board. You can check by swapping horn relays with other relays. If the horn switched on, you easily remove the broken relay and buy a new one from a parts shop.

  1. Horn wire If you check and there is no fault with the fuse and relay any further, check the wires going to the horn.

Inspections will be more difficult because you will have to find where to install the horn. If the grille or headlights or even bumpers need to remove, we recommend that you remove them first for ease of work.

Check the horn wires, which usually have two lines, positive and negative. At present, horn wires may not have polarity because they can wire at any terminal.

Check and clean the terminals if they are dirty. See if the cable fixing nut is loose or not.

Many models of the horn have a grounded connector to the car’s body frame. Check to see if the ground contacts are dirty or loose.

This cable check will be functional if you have a multimeter. A multimeter will help you check if the wires are broke or the horn electromagnet is still in good condition.

  1. Horn If you find that the horn is damaged, you should replace it with a new one immediately. As we said, it is illegal if your vehicle does not have a horn, or it does not work.


Do you need to install the original specification of the horn? The answer is not necessary. You may be able to replace an old horn with a beep type for a bass, soft horn, or whatever sound you want if it is not against the applicable law in your area.


Installing the horn is as easy as removing the mounting bolts and wires and installing the new horn in its original position. You don’t need to change the fuse or relay specifications. These two things are like electric bridges that only make the horns work.


Car horns are a piece of necessary equipment for driving. Pressing the horn can help prevent accidents or reduce the severity of the accident.

You should always check the horn condition. If found that it does not work, you should check and repair it immediately. If your vehicle is under warranty, you can have it repaired or replaced for free.

In case of an old car or buying a used car, we recommend that you check the condition of its use before driving. For the safety of the driver and passengers.

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