U0102: How to Diagnose & Fix — Lost Communication With Transfer Case Control Module
3 vehicles · 2 makes · $300-$4,500 repair
How to diagnose and fix U0102: most-reported vehicles
Ranked by owner reports. Each card gives the symptoms, how to confirm the cause, the fix, parts and sources for that vehicle.
Land Rover Discovery · 2005–2016
The Terrain Response system on the LR3/LR4 develops faults where mode selection fails or the system defaults to General mode only. The rotary selector switch wears out internally, and the shift motor on the transfer case can fail. Corroded connectors at the transfer case are a common root cause. The vehicle remains drivable in General mode but loses off-road capability.
Common Symptoms
- Terrain Response fault on dashboard
- Unable to change terrain modes
- Stuck in General/Normal mode
- HDC (Hill Descent Control) fault
- Low range not engaging
How to Fix
Clean and inspect the Terrain Response selector switch and connectors. Replace the shift motor on the transfer case if faulty. Check the transfer case wiring harness for corrosion — a common failure point is the connector near the exhaust. Update the transfer case ECU software at a dealer.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- IGH500040 transfer-case shift motor assemblyOEMIGH500040
Replace a command- and circuit-test-confirmed failed transfer-case shift actuator Fitment/availability: Discovery 3 and Discovery 4 with the applicable transfer case. Confirm VIN, two-speed transfer-case equipment, motor failure and curr…
As an Amazon Associate, we earn from qualifying purchases; other part links may also earn au7o a commission. Confirm fitment by VIN before buying.
Owner tips & cautions
- TipBefore replacing expensive parts, clean all the connectors at the transfer case with electrical contact cleaner. Corrosion here causes 70% of Terrain Response faults.
Land Rover Range Rover Sport · 2005–2013
The BorgWarner transfer case on the L320 Range Rover Sport suffers from actuator motor failures that prevent the vehicle from shifting between high and low range. The transfer case chain also stretches over time, causing a whining or grinding noise. In severe cases, the chain can skip, damaging the internal gears and requiring a complete transfer case rebuild.
Common Symptoms
- HDC/terrain response fault messages
- Unable to shift into low range
- Whining noise from center tunnel area
- Grinding noise when accelerating
- Vibration at highway speed
How to Fix
Replace the transfer case actuator motor if range selection fails. For chain noise, the transfer case must be removed and the chain replaced. Use Genuine JLR fluid (IYK500010) and replace every 60,000 miles. A full rebuild with new chain, bearings, and seals costs less than a replacement unit.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- IGH500040 transfer-box actuator motorOEMIGH500040
Replace a command- and circuit-test-confirmed failed range/transfer-case actuator Fitment/availability: Range Rover Sport 2006-2013; 2005 requires VIN and installed-unit verification.
- IAB500280 DD295 transfer-box chainOEMIAB500280CHAIN.G
Replace a teardown-confirmed stretched, damaged or slipping transfer-case chain Fitment/availability: Range Rover Sport 2005-2013 with the applicable DD295 transfer box; verify unit identity before internal repair.
- DA7215 DD295 bearing and seal overhaul kitOEMDA7215.G
Renew diagnosed worn bearings and seals during an internal DD295 rebuild Fitment/availability: Range Rover Sport 2005-2013 with DD295 transfer box; does not include the chain and is not a complete universal rebuild kit. Fitment/availabil…
- IYK500010 TF-0870 transfer-case fluid, 1 litreOEMIYK500010 / TF-0870
Refill the verified applicable active transfer case after service or repair Fitment/availability: Range Rover Sport active transfer case where TF-0870/IYK500010 is specified; verify unit, required quantity, level and current fluid specif…
As an Amazon Associate, we earn from qualifying purchases; other part links may also earn au7o a commission. Confirm fitment by VIN before buying.
Owner tips & cautions
- WarningChange transfer case fluid every 60,000 miles WITHOUT exception. Most chain failures are caused by degraded fluid. Use only JLR-specified fluid.
Sources for this issue (4)
- RangeRovers.net: Trans Failsafe Transfer case motor? Noise on actuator signalforum
- RangeRovers.net: Has anyone had to replaced their Transfer Case Motor?forum
- KMotors: Common Problems & Fixes - Range Rover Sport L320manufacturer
- Rover Parts: Land Rover EPB Fault Discovery 4 and Range Rover Sport L320manufacturer
Kia Seltos · 2021–2023
On AWD Seltos (SP2) the 4WD Electronic Control Unit is mounted on the floor under the driver's seat. Snow and slush tracked in on boots melts in the driver's footwell and the meltwater migrates rearward into the ECU, corroding the circuit board. The unit then faults out, illuminating the 4WD warning light and dropping the vehicle into front-wheel drive only. Kia opened voluntary service campaign SC297 covering 2021-2023 AWD Seltos built 11/20/2019-03/02/2023 that were sold or registered in 36 snowbelt states plus DC, which is a strong indicator of how region-correlated the failure is. Owners typically see it first in the second or third winter.
Common Symptoms
- 4WD/AWD warning light illuminated on the cluster
- All-wheel drive stops engaging; vehicle behaves as front-wheel drive
- Traction loss in snow despite AWD badge
- Fault appears after winter driving or in wet-footwell conditions
- Damp carpet or corrosion under the driver's seat
How to Fix
Under campaign SC297 the dealer inspects the 4WD ECU and its wire harness, replaces either or both if water damage is found, and installs a protective cover over the ECU to shield it from future water intrusion. Repair is free on affected VINs. Outside the campaign, replacing the 4WD ECU and harness is the fix; adding the protective cover and using deep all-weather driver's floor mats prevents recurrence. The vehicle remains driveable in FWD with the light on, but AWD is inoperative.
Sources for this issue (2)
Find U0102 by make
Browse every documented model and issue for your make.
U0102 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 U0102 mean?
U0102 stands for "Lost Communication With Transfer Case Control Module." This network (U) code means a module on the vehicle's communication bus has lost contact with the transfer case control module. The transfer case control module manages four-wheel-drive and all-wheel-drive engagement, so loss of communication typically disables 4WD/AWD functions and lights a warning. The fault is most often in the wiring, connectors, power, or ground feeding the module rather than the bus itself. Regular braking and driving generally continue, but the affected drivetrain features may be unavailable.
What are the most common causes of U0102?
The most common causes of U0102 are: Corroded or damaged connector at the transfer case module, Wiring fault (open/short) in the CAN bus or power/ground, Loss of power or poor ground to the module, Faulty transfer case control module, Water/road-salt intrusion into the harness, Blown fuse feeding the module. The specific cause varies by vehicle.
How much does it cost to fix U0102?
Repair costs for U0102 range from $300 to $4,500, depending on the vehicle and root cause.
Which vehicles are affected by U0102?
Au7o has documented U0102 across 3 vehicle models from 2 manufacturers: Kia, Land Rover.
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.