A car horn switch or car horn button can usually be found mounted on the steering wheel or just to the side of the steering wheel. You will find most car horn switches in the centre of your steering wheel. The horn switch is responsible for grounding the relay and allowing power to flow through the relay to the horn when depressed. If a horn switch is not working then it may not sound the horn which could be very dangerous as this is the way you communicate to other drivers and pedestrians.