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HomeTips & GuidesCar Horn Wiring – Everything You Need to Know

Car Horn Wiring – Everything You Need to Know

About Car Horn Wiring: Apart from the signal lights, your horn is the other vital communication system in your car regarding safety. On pressing it button, this system emits a loud sound which warns other road users of your presence.

 But did you know that, like any other system, your car horn can not function without proper wiring? Here, I bring information about car horn wiring, including components, and how to wire and troubleshoot it.

What Is the Purpose of Car Horn Wiring?

As I hinted above, the main purpose of your car horn is to make a sound that alerts other road users. In so doing, you avert any danger and improve your safety and that of other road users, especially in busy areas. 

Your car horn typically features a horn relay, switches, and a wiring harness for power and communication. All these components work in tandem to ensure the proper functionality of the horn. 

A hand pressing a car horn

A hand pressing a car horn

What are the Types of Car Horns?

Generally, the two types of horns you get in most cars are air and electromagnetic. As you would expect, air horns are the basic and simple horn types that use compressed air. 

When you press your car horn button, this compressed air moves toward the horn funnel, which makes the sound. 

On the other hand, an electromagnetic horn is more advanced as it uses an electromagnet. 

An electromagnet is a wire coil around an iron core that becomes a magnet when you pass a current through it. 

Therefore, pressing the horn button creates this electromagnet, which moves a diagram, making the horn sound you hear.

Horn Wiring Components

As promised, let’s discuss your horn components and their function to help you understand how a horn works. 

Generally, your car horn comprises a relay, a horn switch, a wiring harness, and a fuse. First, the horn relay is the one that controls the current that enters your horn. 

Then you have the horn switch which you press to activate the horn relay for the horn to sound. 

Usually, you will find the switch on the steering wheel for convenience and fast reaction when pressing it. 

From there, you have the wiring harness, which links all the horn components together. 

The harness gets power from the car battery and communicates the driver’s input to the horn relay. 

Last, you have the fuse, which protects your horn harness from current surges. 

As you may know, fuses blow when you exceed their rated current, thus disconnecting the circuit and preventing further damage.

A car relay example

A car relay example

How to Wire Your Car Horn Properly

Whatever the case, let’s see some steps you can use to wire your car horn properly:

Gather the materials you need

Before you can even think of wiring your car horn, you will need the following materials to make work easier:

  • Car horn of correct size, voltage, and sound level
  • 12v relay
  • Fuse and fuse holder
  • Correct wire connectors
  • Appropriate gauge wire
  • Toggle switch
  • Wire striper
  • Electrical tape
  • Screwdriver set

Locate your car horn

Now that the materials and tools are ready, you must know where the horn is to wire it. 

Typical, your car horn is in the most accessible area ensuring it does not interfere with other components. You may find it behind the bumper or front grille in many car models. 

Another part you should locate is the horn relay,, mostly under the hood near the battery. However, I recommend checking your car model wiring diagram to know exactly where the horn system is. 

A car diagram will also be useful during the wiring, showing how to route your horn wires.

Prepare to install

As you may expect, there may be another dysfunction horn that you need to remove first. To do this, first, park your car on flat ground and then switch it off. 

Then disconnect the battery to protect you and your installation from electricity. Now, use appropriate tools, such as screwdrivers to loosen and remove your existing car horn. 

From there, prepare your connection wires by cutting the correct length, leaving some allowance for connection. 

Then, strip the insulation at their ends and install the right connectors on their ends.

Disconnecting a car battery

Disconnecting a car battery

Mount your horn

Trusting you got your preferred yet compatible horn, it’s time to install it on your car. You will need a screwdriver and then mount it using the provided mounting hardware, such as screws. 

Ensure it’s secure and tight enough to avoid detaching or loosening when driving.

 Additionally, ensure you install it where other road users can hear it properly. As I said earlier, most install it behind the bumper, where it can’t interfere with other car systems.

Do the Wiring

First, pass one of your wires through the dashboard and connect it to your battery-positive terminal. 

Connect this same wire to your toggle switch near the steering wheel. Next, link another wire from the toggle switch’s other terminal through the dashboard to the relay’s trigger terminal. 

Connect a third wire from the relay power terminal to the horn-positive terminal. 

Then, ground both the horn and the relay by connecting their negative terminal to the metallic body and chassis

Do not forget to install an inline fuse between the toggle switch and the car battery to protect your wiring.

A car horn wiring

A car horn wiring

Secure your connecting and test

Once everything is in place, double-check to ensure all connections are correct. Then, use heat shrink tubing or electrical tape to insulate the exposed wire strands on the joints you made. Reconnect your battery and test your horn to ensure it works.

How to Troubleshoot a Faulty Horn in Your Car

Sometimes, your horn may stop working, which can be dangerous for your car. When that happens, first inspect your horn button to ensure it’s not struck or malfunctioning. 

From there, check the fuse to see if none is blown. In case, you find a dead fuse, replace it first and then test your horn again. 

If the fuses are ok, check the wiring harness for any damage and wear and tear. When you complete this and still have no success, test the relay by swapping it with another.

 Finally, if the relay is on and the horn still does not work, then get another horn.


I hope you can now wire your car horn properly using my extensive research above. In the event that you find any difficulties, I recommend seeking the services of a qualified mechanic.

I am Lillian Yang, having been a sales manager for over 10 years.

I have received many positive reviews from customers. They have praised our excellent service, on-time delivery, and high-quality cable assemblies.

For your projects, please provide cable assembly files/images/smples, etc., so that I can send you a quotation within 24 hours.

Contact me now and let’s get started on building your wire harnesses!

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