Theory Of Operation
WARNING: This page is about a different car, the 2016 Dodge Durango. However, it is still accessible from the selected car via links, so may be relevant.
The Transmission Control Module (TCM) performs various internal tests to verify proper controller operation. If the TCM detects that the variables that dictate the vehicle application are not present, the controller will enter Limp-in mode and illuminate the Malfunction Indicator Lamp (MIL).