7 hours ago
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Some drivers can go years without even touching their car horn, while others employ its 'beep-beep' daily.
If you’re the latter, have you ever had the thought that it could honk its last honk from overuse?
The weird thing about a car horn is that it’s not serviced like you would an engine or transmission, nor is it replaced as frequently as a battery or a globe – so is it indestructible, or can it actually run out?
How does a car horn work?
To answer this question, you must first know how a car horn works.
Working on an electrical current, car horns use a vibration that is amplified based on their shape and size.
When you press down the centre of your steering wheel, it activates a relay that allows electrical current to flow to the horn. This current runs to a diaphragm made from an electromagnet and a metal disc.
Attached to the rear of the thin metal disc is something called an armature, think small electric DC motor, which is attracted to the electromagnet when there is an electrical current flowing to it.
Pulling the armature closer to the magnet flexes the disc inward. As it flexes, there is an additional contact point that is broken, causing the electromagnet to lose current and the metal disc to flex back.
This happens all repetitively in a split second, causing a vibration. The size of the metal disc, and some brands often use a plastic trumpet shroud, changes the sound of the horn, which is what makes horns sound different depending on the car.
Similarly, some modern cars utilise twin horns that operate at different frequencies in tandem to produce a certain sound.
Can a car horn run out of honk?
Unlike, say, windshield washer fluid or petrol, a horn doesn’t just run out of a set volume of honk, but it can stop working with overuse. Contrary to popular belief, it's not compressed air pushed through a trumpet-shaped horn, although some truck and car owners may opt for this setup as an aftermarket modification.
As mentioned above, horns rely on vibration to work, which means that, over time, the metal can deform, causing the pitch to change. This can even cause it to vibrate in a way that will not produce a sound.
It’s similar for the internal connections; the aforementioned electromagnet could suffer a loose connection, or the contact point can snap off with sustained usage. Similarly, dirt and grime can be caught in it and stop the horn from working.
Relays and the internal switch in your steering wheel fail more frequently than the horn itself. Your first point of fixing a faulty horn should be replacing the relay.
Realistically, though, you could hold your horn down forever, and there's a chance that it will outlast you – and certainly the tolerance of those around you.
Zane Dobie comes from a background of motorcycle journalism, working for notable titles such as Australian Motorcycle News Magazine, Just Bikes and BikeReview. Despite his fresh age, Zane brings a lifetime of racing and hands-on experience. His passion now resides on four wheels as an avid car collector, restorer, drift car pilot and weekend go-kart racer.
