Horn The horn of a passenger car is a very important safety device. It allows the operator to alert other drivers of road hazards or dangerous operation that could cause a crash. The horn is also similar to a lighting circuit. Instead of having a switch per se, it uses a button usually located on the steering wheel. This button is also a momentary switch which means that the circuit is broken as soon as it is released. The actual horn is located somewhere in the forward portion of the body of the car, often near the grille and radiator. It is grounded to the frame of the vehicle so only a positive lead wire is required.