Case IH U51 – Transmission Control Module (TCM): Unable to achieve the required engine speed (Engine Speed Error) / PTO Twist Sensor Not Calibrated

During the transmission or PTO calibration procedure, the engine speed was not within the required window (850-950 RPM). This is closely related to code U50, where the TCM has not successfully completed the calibration procedure for the PTO twist sensor.

• MXM
• MXM Series
• MXM 120
• MXM 130
• MXM 140
• MXM 155
• MXM 175
• MXM 190
• Puma Series
• Puma 165
• Puma 180
• Puma 195
• Puma 210
• Puma 225
• Magnum Series
• Steiger Series

1. 1

   For U51 (Engine Speed): Verify that the engine speed is manually set between 850 and 950 RPM

2. 2

   For U51 (Engine Speed): Use the transmission module's H-Menu (H9 or HE menu function) to verify if the engine speed is actually being detected by the controller

3. 3

   For U51 (Engine Speed): Check for a broken CAN link or an unpowered instrument cluster, which can prevent the TCM from reading engine RPM

4. 4

   For U50 (PTO Twist Sensor): Ensure the PTO is completely turned off (if engaged, it will throw a U55 code)

5. 5

   For U50 (PTO Twist Sensor): Inspect the wiring harness and the 3-pin connector at the PTO twist sensor for an open circuit or short to ground

6. 6

   For U50 (PTO Twist Sensor): Check if the PTO twist sensor is physically damaged or incorrectly installed

1. 1

   Preparation

   Ensure the air conditioning is switched off and all electrical/hydraulic applications are deselected. Ensure the handbrake is applied and all levers are in neutral.

2. 2

   Set Engine Speed

   Start the engine and set the throttle so the engine speed is strictly between 850 and 950 RPM (to prevent the U51 code).

3. 3

   Enter Calibration Mode

   Access the transmission calibration mode (H-Menu) via the tractor's instrument cluster or diagnostic switch.

4. 4

   Calibrate the Sensor

   Navigate through the menu until the display shows 'Pt' (indicating PTO twist calibration).

5. 5

   Calibrate

   Press and hold the downshift/calibration button to calibrate the PTO twist sensor.

6. 6

   Verify Calibration

   When the sensor has been calibrated successfully, the display will alternate between 'Pt' and the saved calibration value.

7. 7

   Save Configuration

   Release the button and cycle the key to save the configuration. If the calibration repeatedly fails or throws out-of-range codes, the PTO twist sensor must be replaced.