Case IH U20 – Transmission Control Module (TCU) / Vehicle Electronic Control Unit: Incorrect starting procedure / Incorrect sequence, cycle shuttle lever and clutch pedal

Triggers when the tractor's safety interlock system detects that the operator is attempting to start the engine, engage the transmission, or perform a transmission/clutch calibration without following the correct sequence of controls. The system requires the clutch pedal to be cycled and the shuttle lever to be in neutral to ensure the tractor does not move unexpectedly.

• JXC
• Maxxum MXM 120
• Maxxum MXM 130
• Maxxum MXM 140
• Maxxum MXM 155
• Maxxum MXM 175
• Maxxum MXM 190
• Maxxum 110 EP
• Maxxum 120 EP
• Maxxum 130 EP
• Maxxum 140 EP
• Puma 165
• Puma 180
• Puma 195
• Puma 210
• Puma 225 CVX
• Farmall 95U
• Farmall 105U
• Farmall 115U Pro EP
• Magnum Series
• MX Series
• TG Series

1. 1

   Verify that the operator is following the exact starting or calibration procedure outlined in the operator's manual

2. 2

   Ensure the power shuttle lever is firmly in the Neutral position

3. 3

   Fully depress and release the clutch pedal to see if the code clears

4. 4

   Use the tractor's H-Menu (diagnostic mode) or a service tool to monitor the live state of the clutch pedal potentiometer/switch and the shuttle lever neutral switch for stuck, shorted, or out-of-calibration conditions

1. 1

   Clear the Procedural Lockout

   Turn the key to the ON position. Move the shuttle lever to the Neutral position. Fully press the clutch pedal to the floor, then completely release it. In most cases, this will satisfy the TCU and clear the U20 code.

2. 2

   Calibration Mode

   If you are receiving this code while trying to calibrate the transmission clutches, exit the calibration mode. Restart the tractor, ensure transmission oil temperature is above 10°C (50°F), and restart the calibration sequence exactly as written in the service manual, ensuring you cycle the clutch when prompted.

3. 3

   Inspect Wiring

   If cycling the pedal does not clear the code, remove the cab floor panel or lower dash trim to access the clutch pedal assembly.

4. 4

   Test the Sensor

   Disconnect the electrical connector to the clutch pedal switch/potentiometer. Use a multimeter to check for continuity when the pedal is pressed and released. Check the wiring harness for a short to ground or an open circuit.

5. 5

   Replace and Recalibrate

   If the clutch pedal switch or potentiometer is dead, replace the sensor. After replacement, you must run the transmission/clutch calibration routine so the TCU can learn the new minimum and maximum pedal voltage values.