What is the voltage of a car horn?

[DerekFitz]

The voltage of a car horn is 12V or 24V. Depending on the engine fuel type: The voltage of a car is divided into 12V or 24V based on the engine's fuel type. Gasoline-powered vehicles typically use a 12-volt parallel DC voltage, while diesel-powered vehicles usually employ a 24-volt DC parallel voltage. Introduction to car electric horns: Car electric horns produce sound through the vibration of a metal diaphragm. They consist of components such as an iron core, magnetic coil, contacts, armature, and diaphragm. When the horn button is pressed, current flows through the contacts to the coil, generating magnetic force that pulls down the armature and forces the diaphragm to move. The movement of the armature causes the contacts to open, interrupting the current and causing the coil's magnetic force to disappear. The diaphragm then returns to its original position along with the armature due to its own elasticity and the spring plate's action, closing the contacts again and allowing current to flow through the coil to generate magnetic force once more.

[EmersynDella]

I just tested the voltage of my car's horn last week with a multimeter, and it read around 12 volts. It seems simple, but in actual operation, the voltage fluctuates between 10 and 16 volts due to the interaction between the vehicle's battery and alternator. If you notice the horn becoming weak or sounding erratic, it's likely due to unstable voltage. For example, an aging battery that won't hold a charge or a loose alternator belt not supplying power properly can cause this. I've replaced the horn myself—for a 12-volt vehicle, you must use a horn rated for that voltage; a 24-volt truck horn simply won't work. Always pay attention to the sound of your horn while driving. If the tone suddenly changes, check the electrical circuit immediately—don't wait until it completely fails to fix it.

[StLillian]

After frequent visits to repair shops, you'll realize that 90% of passenger car horns operate on a 12-volt system. Although nominally 12 volts, the voltage fluctuates as soon as the engine starts. If you measure below 10 volts, there's a high chance of wiring leakage or oxidized relay contacts. I've encountered several cases where the horn wouldn't sound—usually due to blown fuses or loose horn connectors. A word of caution: diesel trucks might use a 24-volt system, with double the voltage, so don't connect randomly. If replacing horn components, always check the manufacturer's manual first to confirm voltage specifications.

[Gloria]

Veteran drivers' experience suggests that regular car horns are rated at 12 volts, but don't fixate on the number. The voltage can fluctuate when the alternator's output is unstable, and if it drops too low, the horn will sound as faint as a mosquito's hum. Once encountered a horn failure, and after inspection, it turned out to be corroded battery terminals causing insufficient power supply. Always test the operating voltage range when installing a new horn.