Case IH 5027 – Rear PTO Controller: Rear PTO speed sensor open circuit or short circuit to VBAT

The control module is not receiving a valid frequency or voltage signal from the Power Take-Off (PTO) speed sensor. The system has detected that the electrical circuit is either broken (open circuit) or the signal wire is shorted directly to the battery voltage (VBAT).

• Puma/Mid Range Magnum
• Farmall
• Magnum Series 180, 190, 210, 225, 235, 245, 260, 305, 315, 340, 370
• Puma Series 115, 165, 180, 195, 210, 225
• Maxxum Series 100, 110, 115, 120, 125, 130, 140
• Farmall Series 85C, 95C, 95U, 105C, 105U, 115U
• MX Series MX150, MX170, MX180, MX270, MX275, MX305
• Steiger Series

1. 1

   Inspect the wiring harness leading to the rear PTO speed sensor for broken wires, chafing against the chassis, or rodent damage.

2. 2

   Disconnect the sensor plug and check for moisture, dirt, or corroded/bent pins inside the connector.

3. 3

   Use a multimeter to check the wiring harness between the sensor connector and the PTO ECU for continuity (to ensure no open circuit) and for a short to 12V (VBAT) or ground.

4. 4

   Test the internal resistance of the PTO speed sensor itself. If it reads completely open (infinite resistance) or shorted, the sensor has failed internally.

5. 5

   Verify that the 12V supply fuses for the rear frame/PTO controllers are intact.

1. 1

   Safety First

   Park the tractor on a level surface, engage the parking brake, turn off the engine, and remove the key.

2. 2

   Locate the Sensor

   Locate the PTO speed sensor on the rear PTO housing assembly.

3. 3

   Disconnect

   Unplug the electrical harness connector from the sensor.

4. 4

   Remove the Sensor

   Unbolt or unscrew the faulty PTO speed sensor from the housing. Have a rag ready, as a small amount of hydraulic/transmission fluid may weep from the port depending on the fluid level and model.

5. 5

   Install the New Sensor

   Lubricate the O-ring on the new OEM sensor with clean transmission fluid. Insert the sensor into the housing and tighten it to the manufacturer's specified torque.

6. 6

   Reconnect

   Plug the electrical harness back into the new sensor, ensuring the locking tab clicks into place.

7. 7

   Clear Codes

   Turn the tractor key to the ON position. Use the in-cab monitor or a diagnostic tool to clear the 5027 fault code.

8. 8

   Test

   Start the tractor, engage the rear PTO, and verify that the PTO speed registers correctly on the dash and that the code does not return.