How to Install an Air Horn

Every time you press your car horn button, you’re embarrassed by your vehicle’s sad little horn. So, you’ve finally decided to do something about it, and you’re not messing around. You’re going straight to the big guns—an air horn.

The Different Types of Horns Available

An air horn is often referred to as a train horn because of its super loud sound. A true air horn is piped into a vehicle’s compressed air brake system and is controlled by a cord mounted onto the ceiling in the cab. More modern air horns use different horn relay wiring and are actuated by horn buttons, similar to your stock horn.

Before you run out and purchase a train horn kit, you should evaluate the pros and cons between the air horn vs. electric horn. There may be noise restrictions set by your state or city that limit your horn options, so you’ll want to check with your local DMV.

Air Horn Installation Steps

Once you decide to purchase an air horn, you’ll want to know how to install an air horn so that you can complete installation yourself. Although the installation will vary depending on the horn you select and your vehicle, these installation instructions will give you an idea of what the installation process entails.

Your air horn should include a compressor, a horn relay, tubing and two horns that each produce a different tone.

Step 1. Open the hood of your vehicle and choose a good place to mount the horns. You’ll want them mounted facing at a downward angle to prevent any water from collecting inside. You’ll also want them near the front of the vehicle.

Step 2. Using self-tapping screws and the provided mounting hardware, mount the horns to the vehicle.

Step 3. Mount the compressor to a fender or firewall with the appropriate hardware, and run the provided tubing from the compressor to the horns.

Step 4. Use a multimeter to locate and test the horn wire. The wire should read 0 volts at rest and 12 volts when the horn is pressed. Connect the horn wire to the relay along with power, ground and the 12-volt output to the compressor.

Step 5. Mount the compressor to the fender, firewall or somewhere free of water and excessive heat. Then, connect the negative terminal on the compressor to the ground. Finally, test the air horns by pressing the horn button. If installed correctly, the air horn and your factory horn will sound.