Case IH 3120 (517959.03) - DEC – DEC: PTO twist sensor - not plausible

The PTO twist sensor (also referred to as the PTO torque or torsion sensor) monitors the torque load and rotational twist on the PTO driveline. A "not plausible" condition means the control module is receiving a signal from this sensor that does not make logical sense when compared to other operating parameters (such as engine speed versus PTO output speed). This is typically caused by a damaged sensor, incorrect physical installation, a wiring harness issue, or a sensor that has lost its calibration.

• VESTRUM CVX
• Case IH Magnum Series (210, 220, 235-340 Series 4, 310)
• Case IH Puma Series (180-260 CVX)

1. 1

   Check the PTO twist sensor for physical damage or incorrect installation on the PTO housing

2. 2

   Inspect the 3-pin electrical connector (X-300 or X-1199) and the harness for corrosion, backed-out pins, open circuits, or shorts to ground

3. 3

   Inspect the PTO driveline for mechanical binding or internal damage that could cause erratic torque readings

4. 4

   Attempt to recalibrate the PTO twist sensor before replacing parts, as a lost or corrupted calibration value frequently triggers this code

1. 1

   Park the tractor on a level surface, turn off the engine, and ensure all electrical and hydraulic applications (including the air conditioning) are switched off or deselected.

   Ensure the machine is safe to work on.

2. 2

   Locate the PTO twist/torque sensor on the rear PTO driveline assembly.

   Identify the sensor location for inspection or replacement.

3. 3

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

   Inspect and repair the electrical connection if necessary.

4. 4

   If the sensor itself is faulty, remove the mounting hardware (typically M8 x 25mm hex socket screws) and extract the sensor from the housing.

   Remove the old sensor.

5. 5

   Install the new PTO twist sensor and secure the mounting hardware. Reconnect the electrical harness.

   Install the replacement sensor and restore the electrical connection.

6. 6

   Perform the PTO Twist Sensor Calibration.

   Enter the tractor's calibration mode via the cab display/controls. Navigate to the PTO/Transmission calibration menu. Press and hold the downshift button to initiate the PTO twist sensor calibration. Continue holding until the display alternates between "Pt" and the new calibration value, indicating the calibration was successful. Release the downshift button.

7. 7

   Exit calibration mode, clear the inactive fault codes from the DEC, and test the PTO operation under load to verify the repair.

   Verify the repair was successful and clear the system of old codes.