Theory Of Operation

When Horn operation is requested, the Body Control Module (BCM) either receives a hard-wire signal from the Horn Switch, through the Steering Column Control Module (SCCM), or a CAN Bus message from the RF-Hub (Radio Frequency Hub) Module. When the normally open Horn Switch is depressed, the Horn Switch closes and a ground signal is sent through the Horn Switch Sense circuit, to the BCM.

When the BCM receives the request for Horn operation, the BCM provides a voltage output to the coil side of the Horn Relay, integral to the Power Distribution Center (PDC) Assembly, through the Horn Relay Control circuit. A ground path for the Horn Relay is provided through the PDC Assembly. When the Horn Relay is active, a voltage output is provided through the Fused Horn Control Output circuit, to the Horn. A ground path for the Horn is provided through the wiring harness, to the body sheet metal.