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/START position, the Radio Frequency (RF Hub) Module sends an ignition switch status message over the Controller Area Network (CAN) Bus. The RF Hub Module also sends a redundant hardwired voltage signal to the Body Control Module (BCM), through the Ignition Run/Start Control Output circuit. When the BCM detects the CAN Bus ignition switch status message and the hardwired voltage signal are correct, the BCM provides a voltage output, through the Run/Start Relay Control circuit, to the coil side of the RUN/START Relay, which activates the RUN/START Relay.