Theory Of Operation
WARNING: This page is about a different car, the 2024 Jeep Grand Cherokee L. However, it is still accessible from the selected car via links, so may be relevant.
The purpose of the diagnostic is to detect existing failures on the Private Controller Area Network (CAN) Bus. The Private CAN Bus is a dedicated Bus between the Transmission Control Module (TCM) and the Electronic Shift Module (ESM). This redundant Bus allows the ESM and TCM to communicate with each other when communication is not possible over the Can FD Bus.