The Ultimate Guide to Fixing All Car Horn Problems
The Horn is an important yet one of the most underrated parts of a car. If your car horn is not working, you will have to use the brakes more often. If it starts honking on its own and won’t stop, the problem is even worse, because car horns typically have a minimum sound level of 93 dB and any sound above 85 dB can result in permanent hearing loss with prolonged exposure.
The good news is, unlike many other car problems, fixing a malfunctioning horn is an easy undertaking. Diagnosing a horn is easier than other car noises and fixing it takes less effort than getting rid of the whining noises that cars make.
How Does a Car Horn Work?
The working principle of a car horn is the same as that of a loudspeaker. When you press the horn button, it completes the electrical circuit, and the flow of current is converted to sound. The minimum sound level of car horns allowed in the US is 87dB.
If you need to replace the horn because it stopped working or you need a better-sounding one, always make sure that the one you are getting is within the legal limit of sound level.
Things that make the horn work include:
- A push-button that completes the circuit
- A horn relay that sends current to the horn
- A source of electricity, the battery
- The horn itself
Types of Car Horn Problems
Issues with a car horn can be of three different types:
- The horn stopped working
- It makes a weak sound
- It starts honking on its own and won’t stop
How to Fix a Car Horn That Makes a Weak Sound?
Most cars have more than one horn that collectively creates the horn sound. If one of them goes bad, the system cannot make the correct sound.
However, make sure that your car’s battery is not faulty before you replace the horn. You can use a voltmeter to check the battery. The voltage of the battery should be above 12 volts.
To diagnose which horn is faulty, follow these steps:
- Open the hood of the car.
- Locate the horn in the engine compartment; it is usually near the radiator.
- Ask someone to honk the horn.
- Place both hands on the horn.
- The one that does not vibrate when the horn is honked is the faulty one.
Before you replace the horn, make sure that both electric wires are connected to the horn, and that the wires are not damaged. If the wires are properly connected, it means the horn is faulty and you need to replace it.
To replace the car horn, follow these steps:
- Unscrew the horn from the car and disconnect the electrical connections.
- Get a replacement horn from your local auto parts store.
- Screw the new horn in place and connect the wires.
What to Do if the Car Horn is Not Working at all?
If the horn has stopped working altogether, the problem can be with one of the following:
- Horn fuse
- Horn relay
- The horn itself
If this is the case, the solution is mostly a car horn replacement.
How to Tell if the Fuse is Faulty?
Like any other electrical problem in a car, you need to start the diagnosis from the fuse. Follow these steps:
- Locate the fuse box in your car.
- Read the fuse map to reach the horn fuse.
- Take the fuse out and examine it.
- If the electrical connection inside the fuse is blown, the fuse is faulty, and you’ll need to replace it.
- If the fuse is okay, you need to check the other components.
How to Tell if a Relay is faulty in a Car?
The function of the horn relay is to switch on the horn when you press the horn button from inside the car. It allows the switching circuit to run on a low current and the horn on a high one. By doing so, the switching circuit uses low gauge wires and prevents them from heating up.
If the fuse is working and the horn does not make any sound at all, the relay is most likely the source of the problem.
To diagnose the relay, follow these steps:
- Locate the relay and fuse box in the engine compartment and find the relay that controls the horn using the circuit diagram on the fuse box cover.
- Place your fingers on the relay and ask someone to honk the horn from inside the car.
- If the relay makes a clicking sound when the horn is honked, it is working. If it does not make any sound, the relay is bad.
If both the relay and the fuse are working, the problem is with the horn itself. You can replace it in the same way as we did in the previous part.
How to Fix a Car Horn That Won’t Stop?
If you have a car horn honking by itself even without pressing the button, the problem can be due to one of the following reasons:
- The horn push button is faulty.
- Horn relay is faulty.
- There is a short circuit in the wiring of the horn.
To solve these problems you need to diagnose exactly where the problem is. Here’s how you can do that:
- Locate the fuse box inside the car, take the cover off and see the circuit diagram to find the horn fuse.
- If you remove the fuse and the horn stops, that means the horn push button inside the steering wheel is bad.
- Replace the horn push button with a new one and this will solve the problem.
If removing the fuse does not stop the horn, the problem is most likely with the horn relay. To solve it:
- Open the engine compartment and locate the fuse/relay box.
- Open the relay box and find the horn relay. Removing the relay will stop the horn.
- Swap the relay with another one from the box as there are many of them, usually identical.
- Ask someone to honk the horn from inside the car and if the horn works correctly, you just need a new relay.
If swapping the relay does not solve the problem, there is a short circuit in the wiring of the horn. You can check for that using an electric continuity tester. However, these problems are often complicated and it’s better that you seek professional help.
[Disclaimer] If you have limited knowledge of cars, consult a mechanic instead of trying to rectify the problem on your own.
Frequently Asked Questions
How to replace a car horn?
Locate the horn, unscrew it from the car, disconnect the electrical connectors and swap in the new horn. Make sure you use a horn with sound output within the legal limits allowed in your area.
Can a car horn be repaired?
A car horn can be repaired if the problem is with the electrical supply to the horn. If the horn itself has gone bad, there is no solution for that and you will need to get a new one to replace it. Car horns are made to be disposable and cannot be opened and fixed generally.
Why is my horn honking on its own?
If the horn is honking on its own it can be due to a bad relay, a short circuit in the electric supply of the horn, or a bad horn push button.
How do you check if a horn relay is bad?
Locate the horn relay and swap it with another similar relay in the relay/fuse box. If that solves the problem then the relay is bad. Another way to tell if your horn is bad, is to place your finger on the relay and ask someone to honk the horn. If the relay makes a click, it is good. If it remains silent, it is bad.
How to wire a car horn to a push-button?
To wire a car horn to a push-button, connect the negative terminal of the horn to the body of the car and the positive one to the push button. Give the push button a supply of positive terminal, and the horn will work with the push button.