Case IH PC7 – PCU (Power Control Unit) / Transmission Controller: No Signal From The PTO Twist Speed Sensor

The system is failing to detect an electrical signal from the sensor responsible for measuring the rotational speed and twist (torque) of the Power Take-Off (PTO) shaft. This feedback is critical for the controller to make precise control adjustments to the PTO engagement and operation.

• MXM
• Case IH MXM Series (MXM 120, 130, 140, 155, 175, 190)
• Case IH Puma Series (Puma 140, 180, 210, 260 CVX)
• Case IH Magnum Series
• Case IH Maxxum Series

1. 1

   Check for Related Fault Codes: Verify if other codes are present that might indicate a wiring issue rather than a dead sensor. Look for TC3 (PTO Twist Sensor Short To Ground), TC8 (No Signal From Engine Torque/RPM Sensor), or TC9 (PTO Twist Speed Sensor Over Voltage).

2. 2

   Inspect Wiring and Connectors: Check the wiring harness between the PTO twist speed sensor and the PCU for open circuits, chafing, or shorts to ground.

3. 3

   Check Calibration Status: Look for code U50 (PTO twist sensor not calibrated) or TC6 (PTO Twist Sensor Not Calibrated), which can occur if the non-volatile memory was reset or the controller lost its calibration values.

1. 1

   Access the Sensor

   Locate the PTO Twist Speed Sensor on the rear PTO housing/flywheel area.

2. 2

   Test the Circuit

   Disconnect the sensor and use a multimeter to verify that the PCU is sending the correct reference voltage to the connector, and that there is continuity on the signal and ground wires back to the PCU.

3. 3

   Replace the Sensor

   If the wiring is intact but the sensor is failing to output a signal, remove the retaining screw (typically an M6 x 14mm) and extract the faulty sensor. Install the new sensor and secure it.

4. 4

   Perform System Calibration

   After replacing a sensor or performing a mechanical repair, a Transmission/EDC Calibration must be performed.

5. 5

   Reset Non-Volatile Memory

   Enter the H-Menu and perform the H8 reset procedure. Note that the default calibration value set during the H8 procedure is 3999 for the PTO torque/twist sensor.

6. 6

   Clear Codes

   Clear the TC7 fault code from the PCU and test the PTO engagement to ensure the controller is receiving the speed/twist signal.