Massey Ferguson 04.01.91 – TRANS1 (Transmission Control Module / ECU): Issue With Speed Sensor Values (TRANS1)

The controller is receiving erratic, implausible, or missing signals from the transmission speed sensor, which prevents the system from accurately determining the transmission's rotational speed.

• 7724S
• 5712SL
• 7722
• 7722S
• 5713SL
• 7720S
• 7716
• 7718
• T4
• 7715
• 5710SL
• 7726
• 7726S
• 5711SL
• 7718S
• 7719
• 7714
• 7716S
• 7720
• Tier 4 (2015-2021)
• 7715S
• 7724
• T4 Emissions Generation

1. 1

   Inspect the wiring harness leading to the transmission speed sensor for chafing, breaks, or corrosion.

2. 2

   Test the sensor's internal resistance with a multimeter (standard Massey Ferguson transmission speed sensors spec out at 540 Ohms +/-).

3. 3

   Remove the sensor and check the magnetic pickup tip for excessive metal shavings or debris, which can distort the speed signal.

1. 1

   Preparation

   Park the tractor on flat, level ground, engage the parking brake, and turn off the engine.

2. 2

   Access the Sensor

   Locate the transmission speed sensor on the transmission housing. Note: Depending on the specific model and wheel track width, accessing the sensor may require removing a rear tire to gain clearance.

3. 3

   Removal

   Disconnect the electrical connector from the sensor. Carefully remove the retaining bolt (use penetrating oil if the bolt is seized, which is common) and pull the sensor out of the transmission housing.

4. 4

   Installation

   Clean the mounting port. Insert the new transmission speed sensor and tighten the retaining bolt.

5. 5

   Harness Adaptation

   If you are replacing an older superseded sensor (like 3583286M1) with a newer revision (like 4364876M1), you may need to install an adapter harness (Part # ACW032960A). Reconnect the electrical plug.

6. 6

   Clear Codes & Calibrate

   Use a diagnostic tool to clear the 04.01.91 fault code. If the transmission requires recalibration after the repair, ensure the transmission oil temperature is warmed up to between 35°C (95°F) and 45°C (113°F) before initiating the calibration sequence.