Theory Of Operation
WARNING: This page is about a different car, the 2012 Chrysler 300. However, it is still accessible from the selected car via links, so may be relevant.
The GPEC controller communicates over the CAN C BUS. The transmission controller continuously monitors BUS activity. The CAN C BUS is also used to communicate transmission MIL status to the Engine Controller. If the Engine Controller is unable to communicate with the Transmission Controller, a DTC will set and the Engine Controller will illuminate the MIL.