Case IH U93 – Transmission Control Unit (TCU): F1 did not engage properly.

The transmission controller attempted to engage the F1 (Forward 1) synchronizer gear, but the feedback from the sensors indicated that the physical engagement did not occur or did not complete within the expected parameters.

• Case IH Puma Series: 115, 125, 130, 140, 145, 150, 155, 165, 180, 195, 210, 225 (including CVX models)
• Case IH Maxxum Series: 100, 110, 115, 120, 125, 130, 135, 140, 145, 150
• Case IH MXM Series: 120, 130, 140, 155, 175, 190
• Case IH Magnum Series: 180, 190, 200, 210, MX210, MX230, MX255, MX285
• Case IH Farmall Series: 75N, 85N, 105U, 115U, 120U

1. 1

   Potentiometer Calibration Check: Enter the tractor's transmission calibration mode and observe the displayed synchronizer potentiometer reading. If the voltage/reading is erratic, out of the set limits, or does not change when a shift is commanded, the potentiometer is likely damaged.

2. 2

   Wiring Harness Inspection: Probe the wiring harness from the TCU to the synchronizer potentiometer and the F1 synchronizer solenoids. Check for continuity, chafing, or corrosion at the connectors.

3. 3

   Solenoid & Dump Valve Testing: Use a multimeter to check the resistance of the Clutch A solenoid and the Dump Valve solenoid. Ensure they are receiving proper voltage when commanded.

4. 4

   Hydraulic Pressure Test: Check the transmission charge pressure and inspect the dump valve/proportional valves on the transmission valve block to ensure a valve is not mechanically stuck open or closed.

1. 1

   Prepare machine

   Park the tractor on a flat, level surface, engage the parking brake, and turn off the engine. Ensure all hydraulic pressure is relieved from the circuits before beginning work.

2. 2

   Locate potentiometer

   Locate the F1 synchronizer potentiometer on the exterior of the transmission housing.

3. 3

   Clean area

   Clean the area around the sensor to prevent dirt from entering the transmission housing.

4. 4

   Disconnect wiring

   Disconnect the electrical wiring harness connector from the potentiometer.

5. 5

   Remove sensor

   Remove the retaining bolts/hardware holding the potentiometer in place and carefully extract the sensor.

6. 6

   Install new potentiometer

   Install the new OEM potentiometer, ensuring any O-rings or seals are properly seated. Secure with the retaining hardware.

7. 7

   Reconnect wiring

   Reconnect the electrical harness to the new potentiometer.

8. 8

   Calibrate transmission

   Perform a full transmission calibration using the tractor's onboard display or a dealer service tool. The TCU must learn the voltage limits of the new potentiometer and recalibrate the clutch fill times. Failure to calibrate will result in continued fault codes.