Flash: Drivetrain Control Module (DTCM) Diagnostic and System Improvements
This bulletin involves reprogramming the DTCM with the latest available software.
The technician may find one or more of the following DTCs: U1440 - Implausible Transfer Case Ratio High Received. U0403-00 - Implausible Data Received From Tcase. C1403-92 - Transfer Case Range Position Sensor-Performance Or Incorrect Operation. If only DTC C1403 is present, follow normal diagnostic procedures before updating the DTCM.In addition the customer may describe one or more of the following: Traction Control System light is illuminated. A driveline bump can be heard/felt occasionally when the driver is steady on the throttle at about 20-30% on a flat road while in 4WDAUTO. An excessive electric motor clicking sound from the middle of the vehicle/transfer case area, when on and off the throttle. An excessive electric motor clicking sound with steering wheel movement, most notable in parking lot or low speed maneuvering. A ?Service 4WD? message/fault without commanding a transfer case shift.If only the ?Service 4WD? message/fault is displayed inthe Instrument Panel Cluster (IPC) and no other symptom/conditions are present, follow normal diagnostic procedures before updating theDTCM. The blinking of the ?4WD Low? and ?4WD High? indicator lights at the same time, on the transfer case selector switch.If both 4WD indicator lights on the transfer case selector switch are blinking and no other symptom/conditions are present,follow normal diagnostic procedures before updating the DTCM. During highway/freeway speeds, a bump in the driveline may be felt. This could also be described as a harsh transmission shift.
