U1440 on 2019-2022 Ram 1500: Transfer Case Fault Causes and Fixes

What's Unique About the 2019-2022 Ram 1500

The 5th generation Ram 1500 (DT platform) is known for this specific issue, which prompted Ram's parent company, FCA (now Stellantis), to issue several Technical Service Bulletins. Unlike many trouble codes that point directly to a failed part, U1440 on these trucks is very frequently a software glitch that the DTCM needs an update to correct. This is a well-documented quirk of this particular vehicle generation, with TSB 08-067-21 being a key document that supersedes earlier bulletins and expands the fix to more model years.

Diagnostic Flowchart

Tap your situation to follow the diagnostic path that matches what you're seeing on this vehicle.

Symptoms You May Notice

• "Service 4WD" message on the instrument cluster.
• Traction Control System (ESC) light is illuminated.
• Inability to shift into or out of 4WD modes (4-Auto, 4-High, 4-Low).
• Blinking lights on the 4WD selector switch.
🎬 See a demonstration of these 4WD shifting symptoms in action.
• Driveline bump or clunk felt during steady driving or when letting off the throttle, sometimes described as a harsh shift.
• Clicking sounds from the transfer case area, especially during low-speed maneuvers or when on/off the throttle.
• The 'Service 4WD' light appears intermittently, sometimes after hitting a bump, suggesting a loose connection.

Most Likely Causes

1. Drivetrain Control Module (DTCM) Software Glitch 🔴 High Probability Multiple TSBs (#08-083-20, #08-067-21) were issued by the manufacturer to address this exact software problem on this platform for vehicles built on or before January 12, 2021.
   How to confirm: A dealership can check the current software version of the DTCM against the latest available version referenced in the TSBs using a wiTECH scan tool.
   Typical fix: Reprogramming the DTCM with the latest software. This is a service performed by a dealer and typically takes about an hour of labor.
   Est. part cost: $0
2. Faulty Front Axle Disconnect (FAD) Actuator 🟡 Medium Probability This part, also called a Central Axle Disconnect (CAD), is a very common point of failure. It is located directly under the oil filter, where it can be soaked in oil during changes, potentially leading to failure. Owners on forums frequently report replacing this part to solve U1440 and related symptoms.
   How to confirm: Listen for the actuator attempting to engage when shifting into 4WD. A scan tool may show specific codes for the actuator like C147B-92. 🎬 Watch: Diagnosing the C147B code and front axle actuator failure. A common DIY check is to inspect the electrical connector for oil contamination or damage.
   Typical fix: Replacing the front axle disconnect actuator. This is a common DIY repair that can be done in under an hour.
   Est. part cost: $80-$250
3. Poor Connection at DTCM Connector 🟡 Medium Probability TSB #08-144-22 was issued for a potential connector issue for a very narrow build date range (August 17-18, 2022). However, loose or corroded connectors can happen on any vehicle, especially on frame-mounted modules like the DTCM.
   How to confirm: The DTCM is located on the driver's side frame rail, below the driver's seat area. Visually inspect its electrical connectors for corrosion or damage. Disconnect, inspect pins, add dielectric grease, and reconnect them to ensure they are fully seated.
   Typical fix: Cleaning the connector terminals and ensuring a secure connection. If the connector itself is damaged, it may need to be repaired or replaced.
   Est. part cost: $0-$50
4. Faulty Transfer Case Position Sensor or Shift Motor ⚪ Low Probability While less common than a software glitch, these sensors and motors can fail over time, providing the implausible data that triggers the code. The TSBs mention related codes like C1403-92 for the position sensor, but often state to perform the software update even if this code is present.
   How to confirm: A professional scan tool can read live data from the sensor to see if it's reporting the correct position. The motor's operation can also be tested.
   Typical fix: Replacing the faulty sensor or motor on the transfer case. This can be a misdiagnosis if the root cause is software.
   Est. part cost: $100-$400

Rare But Worth Checking

• Wiring Harness Damage: Rodents are known to chew on the soy-based wire insulation used in modern vehicles. Additionally, corrosion in an inline connector along the passenger side frame rail has been identified by owners as a cause for U1440 and other communication errors. In trucks with the e-locker, the wiring harness to the rear differential has also been found to be a failure point.

Diagnosis Steps

1. Check for TSBs: The first step for any professional is to check for TSBs. For U1440 on this truck, TSB #08-067-21 is the most critical, as it supersedes previous versions and addresses the DTCM software flash.
2. Scan for All Codes: Use a quality OBD-II scanner that can read codes from all modules (DTCM, BCM, PCM). Note any accompanying codes like U0403 or C1403.
3. Verify Software Version: A dealer or well-equipped independent shop must verify if the DTCM software is outdated. If the vehicle was built before January 12, 2021, and has not had the TSB performed, a software update is the most likely fix.
4. Inspect Connectors: If the software is up to date, inspect the electrical connectors at the DTCM (driver's side frame rail) and the front axle actuator (under the oil filter) for looseness, corrosion, or oil contamination.
5. Quick Reset (DIY): Some owners report temporarily clearing the code by disconnecting the battery for 30 minutes to reset all modules. If the code returns quickly, it confirms a hard fault that needs to be addressed.
6. Test Actuator and Sensors: If connections are good, test the front axle actuator and transfer case position sensor circuits and functionality to isolate a potential hardware failure.
7. Inspect Wiring: If all components test good, perform a visual inspection of the wiring harnesses leading to the transfer case, front axle, and rear differential (if e-locker equipped) for any signs of damage, chafing, or corrosion.

Parts You'll Likely Need

• DTCM Software Update — This is not a physical part, but a service. It is the most common fix documented in multiple manufacturer TSBs.
  Trusted brands: Mopar (Dealer Service)
  OEM price range: $150-$250
  Aftermarket price range: N/A
• Front Axle Disconnect (FAD) Actuator (OEM #68216944AA (may be superseded by 68216944AB, 68216944AC, or 52114387AF)) — This is the most commonly failed hardware component that causes U1440 and related 'Service 4WD' symptoms, according to owner forums.
  Trusted brands: Mopar, Dorman
  OEM price range: $150-$250
  Aftermarket price range: $80-$150

Related Codes That Often Appear With This One

• U0403-00 — Stands for 'Implausible Data Received From T-case'. This code is explicitly mentioned in the same TSBs as U1440 and points to the same software/communication issue.
• C1403-92 — Stands for 'Transfer Case Range Position Sensor-Performance Or Incorrect Operation'. This code often appears with U1440, indicating the DTCM is getting conflicting information from the position sensor, which can be part of the same software problem.
• C147B-92 — A code related to the Front Axle Disconnect Actuator. A forum user reported this code appeared with U1440 when their actuator failed, which is a common hardware cause for the 'Service 4WD' light.
• U0102-00 — Stands for 'Lost Communication With Transfer Case Control Module'. This code is cited in TSB 08-144-22 as a possible result of a poorly seated DTCM connector.

Technical Service Bulletins (TSBs) & Recalls

• 08-067-21: Flash: Drivetrain Control Module (DTCM) Diagnostic and System Improvements. Supersedes 08-083-20 and expands the model years to 2019-2021. Cites U1440, U0403-00, and C1403-92 as codes fixed by a software update.
• 08-083-20: The original TSB for the DTCM flash, now superseded by 08-067-21.
• 08-144-22: Drivetrain Control Module (DTCM) Connector Issue. Involves checking the DTCM connection for vehicles built on August 17-18, 2022. Lists U1440 as a potential resulting code.
• 08-043-22 Rev. A: While this TSB is for an HVAC issue, it shows the standard format for bulletins and was investigated as a potential match for the incorrectly cited TSB in pass 1.

Platform-Specific Known Issues

• DTCM Software Glitch: A widespread software issue requires a DTCM flash, as documented in TSB 08-067-21 (which supersedes 08-083-20) for vehicles built on or before January 12, 2021.
• Improperly Seated DTCM Connector: A specific batch of 2022 models built between August 17-18, 2022, were subject to TSB 08-144-22 for improperly seated DTCM connectors that could cause U1440 and other codes.

Mechanic-Grade Diagnostic Values

• Transfer Case Position Sensor 5V Supply (K504 Circuit) — expected: 4.5 - 5.5 Volts. Failure: Voltage below 4.5V indicates an open or high resistance; voltage above 5.5V indicates a short to voltage.
• Transfer Case Position Sensor Signal (T313 Circuit) — expected: > 0.4 Volts. Failure: Voltage below 0.4V triggers a fault code (C1404) and indicates a circuit low condition.
• Resistance of T-Case Sensor Supply or Signal Circuits — expected: < 5.0 Ohms. Failure: Resistance above 5.0 Ohms indicates an open or high-resistance fault in the wiring between the DTCM and the sensor.
• Transfer Case Shift Motor Resistance — expected: 2.0 - 3.0 Ohms. Failure: A reading outside this range suggests a faulty motor.

Scan Tool Commands That Help

• wiTECH (Dealer): Reprogram the DTCM — This is the primary repair procedure outlined in TSBs 08-083-20 and 08-067-21 to fix the common software glitch causing code U1440.
• wiTECH (Dealer): Clear All DTCs — This function is used after reprogramming a module to clear any faults that were set during the flash process.
• AlfaOBD: Read Faults from Drivetrain Control Module — To confirm U1440 and check for other related codes, such as those for the Front Axle Disconnect actuator, without going to a dealer.
• AlfaOBD: Static ECU Initialization — This function can be used to reset a module's learned parameters after a repair or during diagnostics.

Wiring & Ground Locations

• DTCM Connector — On the Drivetrain Control Module, which is mounted to the driver's side frame rail, generally below the driver's seat area.. TSB 08-144-22 was issued for improperly seated connectors on some 2022 models, causing U1440. Corrosion or looseness at this connector can cause intermittent communication loss.
• Front Axle Disconnect (FAD) Connector — On the FAD actuator, which is mounted to the front axle housing directly below the engine oil filter.. This connector is highly susceptible to oil contamination during oil changes, which can lead to a poor connection and actuator failure, triggering a 'Service 4WD' light and related codes.
• K504 Circuit — Wiring between the DTCM and the Transfer Case Shift Motor/Mode Sensor Assembly.. This is the specific circuit designator for the 5-volt power supply to the position sensor. A fault here will cause sensor-related codes like C1403/C1404 that often accompany U1440.
• T313 Circuit — Wiring between the DTCM and the Transfer Case Shift Motor/Mode Sensor Assembly.. This is the specific circuit designator for the position sensor's signal return to the DTCM. An open or short on this wire will provide the implausible data that sets the U1440 code.

Real Owner Repair Stories

• Reddit user TimberPimp (2020 Ram 1500) — Serv 4wd light came on, could hear the transfer case clicking but it would not engage 4WD.
  ❌ Tried (didn't work) Disconnecting the battery.
  ✅ What actually fixed it Pulled code U1440 and replaced the front 4WD actuator (FAD). The issue was resolved.
• 5thgenrams.com user rngzc (2020 Ram 1500) — Intermittent 'serv 4wd' and ESC lights. Codes U1440, U0403, C1403, C140E were present.
  ❌ Tried (didn't work) Restarting the truck would temporarily clear the lights.
  ✅ What actually fixed it The dealer performed a software update to the Drivetrain Control Module (DTCM), referencing TSB 08-144-22, which resolved the problem.
• 5thgenrams.com user Gemlin (2019+ Ram 1500) — 'Service 4WD', 'Service ESC', and 'Service Trailer Brakes' lights were on. Truck would not shift into 4WD.
  ❌ Tried (didn't work) Initial assumption was a failed actuator.
  ✅ What actually fixed it Crawled under the passenger side, located the wiring harness for the 4WD actuator on the front axle, disconnected the plug, and reconnected it securely. This fixed the issue, indicating a poor connection.

OEM Part Supersession History

• 68216944AA → 68216944AB, 68216944AC, 52114387AF (unconfirmed chain) — Standard part revisions for durability or manufacturing improvements.
  Heads up: While later part numbers are generally backward compatible, it is always critical to verify the correct part for your specific VIN. The part is often listed as 'Axle Locker Actuator'.

Model Year Variations Within This Range

• 2019-2021: Vehicles built on or before January 12, 2021, are subject to TSB 08-067-21, which calls for a DTCM software update to fix the U1440 code.
• 2022: A very specific batch of trucks built between August 17-18, 2022, are subject to TSB 08-144-22 for an improperly seated DTCM connector, which can cause U1440. The fix is to simply disconnect and reconnect the connectors.
• 2019-2020: The TSB addressing the software glitch notes that certain symptoms like a 'driveline bump' or 'excessive electric motor clicking' are specific to 2019-2020 models, even though the TSB covers 2021 models as well.