Horn Operation
WARNING: This page is about a different car, the 2020 Ford F-150. However, it is still accessible from the selected car via links, so may be relevant.
The horn switch uses sets of contacts separated by springs. The lower set is connected to ground and the upper set is connected to the horn signal circuit. When the driver airbag is pressed, it pushes down on the upper set of contacts, collapsing the springs and allowing the contacts to touch. When the contacts touch, it completes the circuit and provides a ground signal through the clockspring to the BCM horn input. The BCM then grounds the horn relay coil to energize the relay. When energized, the horn relay provides voltage to the horn, enabling the horn to sound.