Massey Ferguson 4.00.9C – TRANS2: Transmission Input Shaft Speed Sensor Open Circuit

The controller is not detecting a complete electrical path to the input shaft speed sensor. Because the circuit is 'open' (broken wire, unplugged connector, or internally failed sensor), the tractor's computer cannot accurately read the rotational speed of the transmission input shaft, which is critical for managing smooth shifts and precision hydraulic controls.

• 5710SL
• 5711SL
• 5712SL
• 5713SL
• T4
• 4707
• 4708
• 4709
• 4710
• 5608
• 5609
• 5610
• 5611
• 5612
• 5613
• 7614
• 7615
• 7616
• 7618
• 7619
• 7620
• 7622
• 7624
• 7626
• 7714
• 7715
• 7715S
• 7716
• 7716S
• 7718
• 7718S
• 7719
• 7720
• 7722
• 7724
• 7726

1. 1

   Visually inspect the wiring harness running from the TRANS2 controller to the transmission input shaft speed sensor for severed wires, chafing, or disconnected plugs.

2. 2

   Disconnect the sensor plug and inspect the pins for corrosion, moisture, or damage that could interrupt the signal.

3. 3

   Use a multimeter to test the sensor's internal resistance. If the sensor reads as an open circuit (infinite resistance), the sensor itself has failed internally. If the sensor tests fine, the open circuit is located within the tractor's wiring harness.

1. 1

   Locate the Sensor

   Find the transmission input shaft speed sensor on the transmission housing.

2. 2

   Disconnect

   Unplug the electrical harness connector from the sensor.

3. 3

   Harness Repair (If Applicable)

   If the diagnostic checks revealed a broken wire, splice and repair the wiring harness using weather-resistant connectors.

4. 4

   Sensor Replacement (If Applicable)

   If the sensor tested open, unbolt the mounting hardware and pull the old sensor out of the transmission housing.

5. 5

   Install New Sensor

   Insert the new input shaft speed sensor (ensure it is a direct-fit replacement to avoid clearance issues) and secure the mounting bolt.

6. 6

   Reconnect

   Plug the electrical connector back into the sensor, ensuring the weather seal is intact.

7. 7

   Clear Codes

   Use a Massey Ferguson diagnostic tool to clear the 4.00.9C / 04.02.9C fault code from the TRANS2 module.

8. 8

   Test Drive

   Operate the tractor to verify that the transmission shifts smoothly and the fault code does not return.