Theory Of Operation
WARNING: This page is about a different car, the 2017 Jeep Patriot and 2017 Jeep Compass. However, it is still accessible from the selected car via links, so may be relevant.
The Transmission Control Module (TCM) monitors the brake switch 3 signal over the CAN Bus from the Totally Integrated Power Module (TIPM). If the Transmission is shifted into Drive position without confirming that the brake was depressed before the shift, a DTC will set.