U0403 on RAM: How to Diagnose & Fix
Invalid Data Received From Transfer Case Control Module
1 RAM model · 1 documented issue
U0403 on RAM by model: symptoms, diagnosis and fix
Bulletin 08-144-22 lists transfer-case DTCs, traction-control indication and some blinking 4WD indications. Several clicking, bump and Service 4WD conditions are restricted to 2019–2020 trucks; the bulletin does not diagnose a failed shift motor from these symptoms alone. North American 2019–2022 Ram 1500 DT built on or before April 26, 2022 with DH8, DH9 or DHZ transfer case. Two-wheel-drive trucks are excluded. C1403-92 and the listed clicking/bump/Service 4WD branches have 2019–2020 limits.
How to Fix
Verify the transfer-case sales code, build date, symptoms and DTCs against 08-144-22. Diagnose other faults first. If only C1403 is present, use normal diagnosis before a flash; the same caution applies to the isolated Service 4WD or dual-blinking-indicator conditions described for 2019–2020. When qualified, reprogram the DTCM with current software using the specified battery support, then clear reprogramming DTCs. This procedure does not prescribe replacement of the shift motor, transfer case or generic module shown. Normal warranty provisions apply.
Sources for this issue (1)
U0403 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 U0403 mean on a RAM?
U0403 stands for "Invalid Data Received From Transfer Case Control Module." Sets when a module receives invalid data from the Transfer Case Control Module over the bus. Usually a bus integrity, calibration, or transfer-case module fault. On RAM it is documented across 1 model: 1500.
What are the most common causes of U0403?
The most common causes of U0403 are: CAN bus wiring fault or poor ground, Weak battery / low voltage, Calibration mismatch, Failing transfer case control module. The specific cause varies by vehicle.
How much does it cost to fix U0403 on a RAM?
Repair costs vary widely with the root cause and RAM model; each issue on this page carries its own estimate where one is published.
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Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.