Case IH 2401 – Transmission Control Unit (TCU) / Central Control Unit (CCU): Medium / reverse range synchronizer not calibrated or bad calibration

The voltage signal coming from the potentiometer of the medium/reverse range synchronizer is out of the expected calibrated band. This fault is specific to machines equipped with Semi-Powershift (SPS) transmissions.

• Optum
• Case IH Puma 125
• Case IH Puma 140
• Case IH Puma 165
• Case IH Puma 180
• Case IH Puma 195
• Case IH Puma 210
• Case IH Puma 225
• Case IH Maxxum Series
• Case IH Steiger Series

1. 1

   Turn the ignition switch OFF. Disconnect the medium range clutch solenoid connector (often labeled X-642).

2. 2

   Measure the resistance between solenoid terminal 1 and terminal 2. The resistance should be between 8 - 11 Ohms.

3. 3

   Inspect the wiring harness between the CCU, the synchronizer potentiometer, and the solenoid for open circuits, shorts to ground, or shorts to positive voltage.

4. 4

   Ensure there are no external power supplies improperly connected and that the tractor's charging system is functioning correctly, as voltage irregularities can trigger this code.

1. 1

   Attempt Calibration

   Start by attempting to recalibrate the forward/reverse synchronizer using the tractor's calibration menu. The engine must be running with the transmission in neutral and the clutch released.

2. 2

   Inspect/Replace the Solenoid

   If calibration fails and the diagnostic resistance check on the medium range clutch solenoid yielded a result outside the 8 - 11 Ohms range, remove and replace the medium range clutch solenoid.

3. 3

   Inspect/Replace the Potentiometer

   If the solenoid tests fine but the code persists (or if related codes like U97/U98 are present), the synchronizer potentiometer is likely damaged or sending a signal out of range. Replace the synchronizer potentiometer.

4. 4

   Clear Codes and Recalibrate

   After replacing the faulty component (solenoid or potentiometer) and verifying the wiring harness, clear the fault codes from the CCU and perform the Semi-Powershift transmission calibration procedure again to marry the new sensor/solenoid to the control unit.