Theory Of Operation
WARNING: This page is about a different car, the 2013 RAM 3500 HD and 2013 RAM 2500 HD. However, it is still accessible from the selected car via links, so may be relevant.
The Body Control Module (BCM) receives the network communication message from the Steering Control Module indicating horn operation is requested. The BCM provides a voltage output through the horn relay control circuit, which connects to the coil side of the Horn Relay.