A fully functioning car horn is an important element of a roadworthy vehicle. It alerts other motorists and pedestrians to the vehicle’s presence, avoiding potential collisions and accidents. Unfortunately, there will always be instances when the horn fails altogether. Fixing a broken or non-functioning car horn is easy. You only need to check the individual components of their working condition and replace them if necessary. Here’s how.
Start With the Fuse
Check your owner’s manual to determine the location of the fuse box. Most vehicle manufacturers put theirs on the dashboard near the driver. There is another fuse box in the engine bay of the car. Start with the most accessible first – the one in the dashboard.
Open the fuse box. The back panel will often have a diagram following the arrangement of the fuses in the box. If not, check your manual again. These have numbers. Check the number corresponding to the fuse for the car horn. Pull the fuse from its slot using a pair of fuse pliers.
Inspect the fuse. It looks like a very small electric plug with two prongs. It comes with a translucent casing, allowing you to see a U-shaped wire connecting the two prongs. If there is a break in this wire, then you have a blown fuse. In such case, you will need to purchase a fuse of the same specs as the busted one.
If the wire is not broken, do not rejoice yet. You have to confirm it with a multimeter. Switch the multimeter on. Form a circuit by touching the probes of the multimeter on each of the terminals of the fuse. If you get a reading that says “out of limits”, then you have a blown fuse. Replace the fuse with a new one.
If, however, you get a numerical reading in the multimeter, then the fuse is not your problem.
Check the Relay
If the problem is not the fuse, then you can turn your attention to the horn relay. You will need to access the relay box under the hood of your car. The easiest way for you to determine whether it is still functioning or not is to replace it with an identical relay from the same box. Manufacturers often design their relays so that they are swappable. As such, swap an identical relay to the car horn relay. If the horn works, then you know that the horn relay needs replacement.
Test the Relay Switch
It may also be wise to check the relay switch. Get your multimeter and set it to measure Ohms. Remove the relay and touch a multimeter probe to the relay socket. Touch the other multimeter probe to the negative terminal of the car’s battery. Ask an assistant to press the horn button in the steering wheel. You should see numbers on the digital screen of the multimeter. If you see “out of limits”, then you have a malfunctioning relay switch. You will also need to replace this.
Check the Horn Switch
If the relay switch works fine, then your next focus should be on the horn switch. Unfortunately, this will require a bit of work. Car manufacturers put the horn switch in the steering wheel pad. You will have to remove the steering wheel pad to gain access to the horn switch.
Here’s the problem. If your vehicle comes with a standard driver’s airbag, this system is also found in the steering wheel pad. You have to be very careful in removing the outermost panel to prevent the accidental deployment of the airbag. That is why, in most cases, it is best to take the car to a professional so they know how to remove the steering wheel pad without triggering the airbag.
In normal operation, depressing the horn button allows for the flow of electricity to the horn assembly via the relay. If it remains open, then you will not be able to sound your horn.
Test the Car Horn
If everything checks out fine from the fuse to the relay and the horn and relay switches, the next thing to check is the car horn itself. Most cars have the horn mounted behind the grille of the car. Some may have it on the car’s radiator core.
Remove the connector for the car horn. Connect one end of a jumper wire to the positive terminal of the horn. Connect the jumper wire’s other end to the car battery’s positive terminal. Next, get another wire and connect the negative terminals of the horn and the battery. The moment you touch the wire to the battery’s negative post, the horn should work. If there is still no sound, then you have to purchase a new horn and replace the old one.
Test the Horn Circuit
Before you replace the horn, it is wise to check the circuit first. You may have a functioning horn, but the wirings are not delivering the power to the horn. First, test the circuit’s ground side. You may have to check your owner’s manual to determine the ground side of the car’s horn circuitry.
Set the multimeter to measure Ohms. Touch one of its probe to the horn’s negative connector pin. Touch the other meter probe to the horn ground. If you see numbers in the display, then this means the ground circuit is working. But if you read “out of limits”, then have an automotive technician to identify the cause.
If the ground circuit is working, then check the circuit’s power side. Set the multimeter to measure Volts. Touch a meter probe to the positive horn connector pin. Touch the other meter probe to the horn ground. If it is working, then you should see numbers in the multimeter’s display. If not, then you know that this is a job for professionals to trace the cause of the problem.
Fixing a car horn is quite easy. You only need to isolate the cause of the problem and replace the broken part. However, there will always be instances when you need professional assistance.
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