This TSB applies to 2011-2012 Ram 1500 pickup and RAM regular Cab Chassis (Mexico) and 2012 RAM 3500 pickup, 3500 Cab Chassis, 2500 pickup and 4500/5500 Cab Chassis vehicles.
Some owners may get 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 TechCONNECT, verify no DTCs are set. If DTCs are present other than C2201, record them and repair as necessary before proceeding further.
NOTE: Install a battery charger to insure that battery voltage does not drop below 13.2 volts. Do not allow the charging voltage to climb above 13.5 volts during the flash process.