Principles Of Operation

Horn

Principles of Operation

The Body Control Module (BCM) supplies the switched and control voltage to the horn relay (integrated into the BCM (Body Control Module)).

The horn switch consists of 2 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 air bag module 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 the ground signal which is routed through the clockspring, Steering Column Control Module (SCCM) and then to the BCM (Body Control Module). The BCM (Body Control Module) then energizes the horn relay sending voltage to the horn, enabling the horn to sound.

The BCM (Body Control Module) also provides a momentary ground to the horn relay when the anti-theft system is armed, and an alternating on/off ground when the panic button is pressed on the Remote Keyless Entry (RKE) transmitter.