Owners of a 2012 Dodge Ram 3500 equipped with an electronic transfer case and built before Jan. 6, 2012, may see a “Service 4WD” light in the cabin compartment node. The technician may find that C2201 (FDCM/DTCM internal diagnostic trouble code) is set in the DTCM. When the system detects this, it shuts down the 4WD capability for the remainder of the drive cycle.
Using a scan tool (wiTECH), verify that no other DTCs are set. If other DTCs are present, record and repair as needed first.
Connect wiTECH to the vehicle. Place the ignition in the run position and select DTCM. Select Data tab. Scroll down to “DTCM internal DTC Reason.” If this now reads “Task Failure,” reprogram the DTCM with software release 12.02 or higher.