Massey Ferguson 4.03.85 – TRANS / TRANS1: Issue With Signal From Transmission Mounted Engine Speed Sensor (TRANS) / Issue With Speed Sensor Values (TRANS1)

The transmission controller is receiving an erratic, out-of-range, or missing signal from the engine speed sensor that is mounted on the transmission housing. Without accurate speed data, the transmission cannot properly synchronize shifts, which can lead to rough shifting, poor fuel economy, or the tractor refusing to move.

• 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
• 7716
• 7718
• 7719
• 7720
• 7722
• 7724
• 7726

1. 1

   Visually inspect the sensor cable for broken wires, wear due to interference with moving components, or heavy contamination (oil mist, dirt, moisture)

2. 2

   Disconnect the sensor harness and inspect the terminal pins for corrosion, pushed-out pins, or loose connections

3. 3

   Perform a resistance test on the sensor using a Volt-Ohm meter across the terminal pins (healthy sensors typically read around 540 ohms or 900-2000 ohms depending on variant; an open or 0 ohm reading indicates internal failure)

4. 4

   Perform a ground short test by measuring resistance from each terminal pin on the sensor to the chassis ground (must be infinite/open circuit; continuity indicates a shorted sensor)

1. 1

   Turn the ignition OFF, apply the parking brake, and ensure the tractor is secured.

   Ensure the tractor is safe to work on before beginning repairs.

2. 2

   Locate the transmission-mounted engine speed sensor on the transmission housing.

   Clean the area around the sensor to prevent dirt from falling into the transmission.

3. 3

   Disconnect the electrical harness connector from the sensor.

   Carefully unplug the harness.

4. 4

   Unbolt/unscrew the faulty speed sensor from the transmission housing and remove it.

   Remove the old sensor from the housing.

5. 5

   Install the new OEM transmission speed sensor.

   Ensure any O-rings or seals are properly seated during installation.

6. 6

   Reconnect the electrical harness.

   Ensure the locking tab clicks into place.

7. 7

   Use a diagnostic tool to clear the stored 04.03.85 fault code from the TRANS module.

   Clear the code after the new sensor is installed.

8. 8

   Test drive the tractor.

   Ensure the transmission shifts smoothly and the code does not return.