This TSB applies to 2011-2012 Ram 1500, 2012 3500 and Can Chassis, 2012 2500, 2012 4500/5500 Cab Chassis and 2011-2012 regular Cab Chassis (Mexico).
Some customers may see a “Service 4WD” light in the Cabin Compartment Node (CCN). Upon further investigation, 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.
This condition is not monitored when operating in 2WD mode. Updating the DTCM software will correct the condition.
Using a scan tool (wiTECH) with the appropriate diagnostic procedures available in TechCONNECTm verify that no DTCs are set. If DTCs are present other than the one listed here, record them and repair as necessary before proceeding further.
NOTE: Install a battery charger to ensure that battery voltage does not drop below 13.2 volts. Do not allow charging voltage to climb above 13.5 volts during the flash process.