U0103 on RAM: How to Diagnose & Fix
Lost Communication With Gear Shift Control Module "A"
1 RAM model · 1 documented issue · $300-$900 repair
U0103 on RAM by model: symptoms, diagnosis and fix
4WD-equipped Ram 1500 trucks use an electric shift motor (encoder/gear motor) bolted to the BorgWarner transfer case to move between 2WD, 4WD-Auto, 4-High and 4-Low. The motor's internal plastic gears wear or strip, and water/road-salt intrusion corrodes the connector and motor windings, so the system fails to complete a shift. The dash shows 'Service 4WD,' the mode indicator blinks without engaging, and grinding or clicking can be heard from under the truck. A large share of Ram 4WD-engagement complaints trace to the shift motor rather than internal transfer-case damage, so it is usually a relatively affordable fix if caught early. FCA TSB 08-094-20 provides a Drivetrain Control Module (DTCM) software update for 2016-2020 trucks with this symptom.
Common Symptoms
- 'Service 4WD' warning message
- 4WD will not engage or disengage
- Mode indicator blinks but never locks in
- Grinding or clicking under the truck when shifting modes
- Stuck in 2WD or stuck in 4WD
How to Fix
Scan for transfer-case/DTCM codes and check the connector for corrosion first. Apply the DTCM software update (TSB 08-094-20) if applicable. If the motor's gears are stripped or windings are open, replace the transfer case shift/gear motor (verified Mopar PN 68450803AA for 2019-2025 DT; actuator 68369691AD) and reprogram if required. Keep the connector clean and protected from salt; for trucks used in snow/off-road, periodic inspection prevents being stranded in the wrong mode.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Genuine Mopar 68089746AC transfer-case actuator
Confirm VIN, case tag and connector because the catalog also covers HD trucks and not every 1500 configuration.
- Replacement 914-006 7-pin BW44-44/BW44-45 transfer-case motor
The listing excludes 2016, so do not extrapolate.
- Genuine Mopar 68679351AA active transfer-case shift motor
Confirm VIN and transfer-case sales code.
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Sources for this issue (3)
U0103 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does U0103 mean on a RAM?
U0103 stands for "Lost Communication With Gear Shift Control Module "A"." Sets when a module loses data-bus communication with the Gear Shift Control Module 'A' (electronic/shift-by-wire gear selector) and no longer receives its expected messages. Common on vehicles with electronic shifters. On RAM it is documented across 1 model: 1500.
What are the most common causes of U0103?
The most common causes of U0103 are: Open, shorted, or chafed bus wiring to the shift control module, Corroded or loose shift module connector, Blown fuse / lost power or ground to the module, Low battery voltage, Failed gear shift control module. The specific cause varies by vehicle.
How much does it cost to fix U0103 on a RAM?
Published repair estimates on RAM range from $300 to $900 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
Looking for U0103 on a different make?
View U0103 across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.