Theory Of Operation
WARNING: This page is about a different car, the 2006 Dodge Magnum, 2006 Dodge Charger, and 2006 Chrysler 300. 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 MIL.