Possible Cause

WARNING: This page is about a different car, the 2002 Dodge Intrepid, 2002 Chrysler Intrepid, 2002 Chrysler Concorde, and 2002 Chrysler 300M. However, it is still accessible from the selected car via links, so may be relevant.

TCM communication errors will result from the following conditions:

Open in fused B+ circuit to PCM.
Open in fused ignition switch output (RUN) circuit.
Open in fused ignition switch output (START) circuit.
PCI circuit open.
Open ground circuit.
Other BUS problems.
Faulty BCM.
Faulty PCM.