Theory of Operation
WARNING: This page is about a different car, the 2011 Jeep Patriot and 2011 Jeep Compass. However, it is still accessible from the selected car via links, so may be relevant.
The Transmission Control Module receives vehicle information over the CAN Bus from the FCM/TIPM and stores this information in the EEPROM of the controller. This information is compared information received over the CAN Bus. If the information does not match, the DTC will set.