Principles of Operation
WARNING: This page is about a different car, the 2007 Ford Ranger. However, it is still accessible from the selected car via links, so may be relevant.
The horn switch is incorporated within the steering wheel. When the switch is closed, ground is supplied through the clockspring from the vehicle harness. The horn relay is then energized, supplying voltage to the horn enabling the horn to sound. The horn relay is integral to the smart junction box (SJB).