If you have a car horn honking by itself, there are a few ways you can diagnose it and turn it off. Find out how to quiet a car horn that won’t turn off and diagnose the cause in this article and video.
What Causes a Horn to Not Stop Honking By Itself?
Bad Relay
The relay is the most likely cause of a car horn that won’t turn off on its own, so we recommended checking that area first, which is covered in the steps below.
Stuck Horn Button
The horn button on the steering wheel could be sticking and may need to be checked for a broken spring or damaged horn pad.
Shorted Body Control Module
There could be a comfort or body control module that’s shorted and causing the horn to honk by itself.
Electrical Wiring Issues
There may be a wiring issue that is causing the horn to keep honking, like a short circuit.
Aftermarket Accessories Like Remote Start
Some aftermarket accessories like remote start could trigger the horn to honk by itself.
How to Diagnose a Car Horn Honking By Itself
Steps to Diagnose a Car Horn That Won’t Turn Off and Keeps Honking
- Tap the Horn Button and Check It for Sticking
Sometimes the horn button can stick. Press around the horn button on the steering wheel. Give it a shake and feel if the horn is stuck down in any areas by pressing and tapping around it.
- To Shut the Horn Off, Disconnect the Negative Terminal on the Battery, or the Electrical Connectors on the Horn
To shut the horn off immediately, disconnect the negative battery terminal. You can also disconnect the electrical connector from the horn. Most vehicles have two horns at the front. The horns usually have two wires, but some have single wires. In some cases the horn may be the cause of the electrical short, but this is unlikely.
- Remove the Horn’s Fuse and See If It’s Still Honking by Itself
Open the hood and find the fuse box. Find the horn fuse. Remove the fuse.
Reconnect the battery and see if the horn is still going. It shouldn’t be honking, but there could be a wiring short causing it to keep going.
- Reinstall the Fuse and Remove the Relay
Bad relays are a common reason for a horn that won’t stop honking itself. The relay contact could be sticking together and keeping the horn on.
Find the relay and remove it. Reinstall the fuse and see if horn is going. It shouldn’t be.
Grab a relay that matches the number on the horn relay (sometimes the AC relay has the same number). If the horn is not honking with the fuse and a new relay inserted, there is probably a bad relay.
If you swap the relay, put the fuse in, reconnect the battery and the horn still honks by itself whenever a different relay is in, the most likely cause is between the relay and the horn button.
- Remove and Disconnect the Airbag, and Check the Horn Button
Remove and disconnect the airbag. With the airbag disconnected, replace the negative battery terminal. Don’t turn the key on. In most vehicles the horn will work with the vehicle off.
Check the switch by pressing it and feeling for sticking. There could be a broken spring, and you may have to replace the horn pad or spring.
Learn How to Fix More on Your Car Than a Horn Honking By Itself
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