Theory Of Operation
WARNING: This page is about a different car, the 2017 Jeep Cherokee. However, it is still accessible from the selected car via links, so may be relevant.
When the ignition is in the RUN position, the Radio Frequency (RF Hub) Module sends an ignition switch status message over the Controller Area Network (CAN) Bus. When the Body Control Module (BCM) receives this CAN Bus ignition switch status message, the BCM provides a ground output, through the Run Relay Control circuit, to the coil side of the RUN 1 Relay, which activates the RUN 1 Relay.