Diagnostic Procedure
WARNING: This page is about a different car, the 2009 Dodge Avenger and 2009 Chrysler Sebring. However, it is still accessible from the selected car via links, so may be relevant.
Refer to DTC-Based Diagnostics/MODULE, Totally Integrated Power (TIPM) - Diagnosis and Testing and perform the U0100-Lost Communication with ECM/PCM diagnostic procedure.