A horn on a car will fail when there is a problem with its wiring or speaker unit. Generally there are two speakers used on a car and both can be found in the front of the vehicle, behind the bumper.
If there is an issue with the horn itself, the speakers will still create a faint or weak sound. If this occurs, follow these instructions to troubleshoot the horn:
- Locate the horn assembly
- Use the wiring to find the speakers
- Clean the wire terminals
- Check the ground for the horn assembly
Open the engine compartment and locate the horn assembly.
The speakers are mounted behind the front bumper.
Inspect the wire terminals and clean off any corrosion. Reconnect them and try the horn again. If it still does not work proceed to step 4.
Inspect the ground and clean off any corrosion, then reconnect it. Check the horn again. If the unit still does not work, replace the assembly.
If the voltage on the assembly is good, check the connection between it and the button. Modern vehicles will have the horn button on the inside of the steering wheel next to the air bag. If the button turns out to be the root of the issue the vehicle should be inspected by a certified technician, as accidental deployment of the airbag can result in lethal harm.