RAM 1500 2019–2021 — technical service bulletin
Bulletin 0806721 · NHTSA communication 10221219 · issued Apr 28, 2021
Technical service bulletin
communication type
Electrical System
component
2019–2021
model years
3
vehicle entries
Official summary
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 T-case. C1403-92 - Transfer Case Range Position Sensor-Performance Or Incorrect Operation(2019-2020 Vehicles Only). If only DTC C1403 is present, follow normal diagnostic procedures before updatingthe DTCM.In addition the customer may describe one or more of the following:Traction Contro
Vehicles covered
What a TSB means. Technical service bulletins are repair guidance manufacturers send to dealers — they are not recalls, and repairs are not automatically free (warranty extensions are an exception worth checking). The full document is available via NHTSA’s vehicle lookup.