Case IH 3120 – Engine Control Module (ECM): PTO Twist Sensor - Not Plausible

The PTO Twist Sensor's signal is erratic, out of expected bounds, or does not logically match other operating parameters. This sensor measures the physical twist (torque) on the driveline under load to boost engine horsepower.

• Case IH Magnum Series
• Case IH Puma Series
• Case IH Steiger Series
• Case IH Maxxum Series

1. 1

   Inspect the wiring harness leading to the PTO Twist Sensor (connector X-262 or X-300) for open circuits, shorts to ground, or damaged pins.

2. 2

   Check if the sensor is physically damaged, loose, or incorrectly installed on the driveline.

3. 3

   Inspect the driveline for mechanical issues or excessive wear that could cause erratic twist readings.

4. 4

   Check if the sensor simply lost its calibration (often accompanied by code 3123 or U79).

1. 1

   Locate the Sensor

   Locate the PTO Twist Sensor on the rear driveline assembly, situated between the hydraulic pump drive and the PTO drive.

2. 2

   Inspect/Repair the Harness

   Disconnect the 3-pin electrical connector. If the connector is corroded, melted, or damaged, splice in a new replacement connector.

3. 3

   Replace the Sensor

   If the wiring is sound and the sensor is physically damaged or internally shorted, remove the retaining hardware, extract the old sensor, and install the new PTO Twist Sensor. Ensure it is seated correctly to avoid future 'Not Plausible' readings.

4. 4

   Perform Sensor Calibration

   After replacing the sensor or repairing the wiring, calibrate the sensor via the tractor's electronic calibration menu (H-Menu). Navigate to the PTO twist calibration screen ('Pt'). Ensure the PTO is turned OFF (starting the PTO during this process will cause a U55 calibration error). Press and hold the calibration/downshift button until the display alternates between 'Pt' and the new calibration value.