Case IH U31 – Transmission Control Module (TCU) or Electronic Draft Control / Transmission module: Wheel speed sensed - tractor moving

Triggered specifically during the transmission calibration procedure. The system requires the tractor to be completely stationary with the parking brake engaged. If the transmission controller detects wheel movement via the output speed sensor, or if it detects that the handbrake is not applied, it will abort the calibration and throw the U31 code.

• JXC
• Maxxum Series (MXM 120-190, MX170)
• Puma Series (165, 180, 195, 210, 225)
• Magnum Series (MX210-MX285, 380)
• Steiger Series
• CX Series
• TN Series

1. 1

   Verify the handbrake/parking brake is fully applied

2. 2

   Check for actual tractor movement or lurching due to worn brakes

3. 3

   Ensure the high range is selected, as required by some service manuals

4. 4

   Test the parking brake switch to ensure it sends an 'applied' signal to the TCU

5. 5

   Inspect the transmission output speed sensor and wiring harness for false speed signals

6. 6

   Check for internal mechanical faults causing gear movement without wheel movement

1. 1

   Reposition the Tractor

   Park the tractor on flat, level ground.

2. 2

   Re-attempt Calibration

   Fully apply the handbrake. If the brakes are mechanically sound but the code appeared, OEM manuals advise to move the vehicle forward slightly and repeat calibration.

3. 3

   Test/Replace the Parking Brake Switch

   Locate the parking brake switch at the base of the handbrake lever assembly. Use a multimeter to test for continuity when the brake is engaged. If it fails to close the circuit, replace the switch.

4. 4

   Test/Replace the Transmission Speed Sensor

   Locate the transmission output speed sensor on the transmission housing. Inspect the wiring harness and connector for corrosion or breaks. If the wiring is intact but the sensor is reading false movement, replace the speed sensor.

5. 5

   Final Calibration

   Once the faulty switch or sensor is replaced, re-run the transmission calibration procedure (e.g., the H2 menu for clutches A and B) ensuring the tractor remains completely still.