Massey Ferguson 4.02.85 – Transmission Control Module (TRANS / TRANS1): Issue With Speed Sensor Values (TRANS1)

The control module is receiving erratic, missing, or out-of-range signals from the speed sensor mounted on the transmission, which monitors the rotational speed of the transmission input/engine speed.

• 5710SL
• 5711SL
• 5712SL
• 5713SL
• T4
• 5608
• 5609
• 5610
• 5611
• 5612
• 5613
• 7714
• 7715
• 7715S
• 7716
• 7716S
• 7718
• 7718S
• 7719
• 7720
• 7720S
• 7722
• 7722S
• 7724
• 7724S
• 7726
• 7726S

1. 1

   Inspect the wiring harness and connector at the transmission speed sensor for corrosion, moisture, or physical damage

2. 2

   Disconnect the sensor and measure the resistance across its pins (should read approximately 450 Ohms +/- 20 Ohms when the tractor is stopped)

3. 3

   Check for an alternating AC voltage signal from the sensor when the pinion/gear is rotating

4. 4

   Temporarily swap the transmission-mounted engine speed sensor with the axle speed sensor (if identical) to see if the fault follows the sensor

1. 1

   Locate the Sensor

   Find the transmission-mounted speed sensor, typically located close to the gearbox cover or flywheel housing.

2. 2

   Removal

   Disconnect the electrical connector. Unscrew and remove the faulty sensor from the transmission housing.

3. 3

   Preparation

   Clean the mounting area to prevent contamination.

4. 4

   Installation

   Apply a small amount of thread sealant (such as Loctite 5922) to the threads of the new sensor.

5. 5

   Set the Air-Gap

   Screw the new sensor in until it bottoms out (in abutment on the pinion) to establish the correct air-gap, then back it off slightly if specified by your specific model's service manual.

6. 6

   Reassembly

   Reconnect the electrical harness securely.

7. 7

   Clear Codes

   Use a diagnostic scan tool to clear the 04.02.85 DTC from the Transmission Control Module and test drive the tractor to ensure the code does not return.