A horn, as the name implies, is a device on a vehicle that is used to signal danger, arouse attention, or communicate with the driver in another vehicle. It is an important safety feature in an automobile and is required in many states.
Most horns found in passenger vehicles rely on electricity to vibrate a metal diaphragm inside. When you press on the horn button (located ahead of the airbag module in the center of the steering wheel), a relay sends an electrical signal to the horn. Actually, there are usually two horns, each sounding a different frequency, a high note and a low note.
The horns are mounted in the front of the vehicle, typically behind the grille near the front bumper.
When your horn is working properly, you should hear a strong blast composed of two notes. If a horn fails, you will hear either a weak sound coming from the horn, or you will hear the sound of only one horn, one note. If you hear nothing at all, the problem is less likely to be a bad horn and more likely to be a bad fuse or relay that switches the horns on and off when you press the center of the steering wheel. It is possible for both horns to fail simultaneously if they are quite old, but it is not common.
To replace a horn in your vehicle, a technician will need to gain access to its mounting location. That might involve removing the grill or the front bumper cover, although that is not always the case. Prior to disconnecting the horn, the technician will disconnect the battery, taking care to preserve the vehicle computer memory.
Once access to the horn is made, the technician will unplug the electrical wire, unbolt the horn bracket from its mount, and remove the horn. The mounting surface will be cleaned to ensure a good electrical ground for the new horn before it is bolted in place. The wire is plugged in, the battery connected, and the horn tested for proper operation.