Massey Ferguson 4.X.91 – Transmission Controller (TRANS1): Issue With Speed Sensor Values (TRANS1)

No engine speed value detected while the current forward speed is greater than 0. The transmission controller detects that the tractor is moving forward, but the engine speed sensor (X481) is reporting 0 RPM. This discrepancy points to a failure in the engine speed sensor circuit, a faulty sensor, or a wiring issue.

• 5710SL
• 5711SL
• 5712SL
• 5713SL
• T4
• 5455
• 5460
• 5465
• 5470
• 5475
• 5480
• 5608
• 5609
• 5610
• 5611
• 5612
• 5613
• 5710 SL
• 5711 SL
• 5712 SL
• 5713 SL
• 6445
• 6455
• 6460
• 6465
• 6470
• 6475
• 6480
• 6485
• 6490
• 6495
• 6497
• 6499
• 6712 S
• 6713 S
• 6715 S
• 6716 S
• 6718 S
• 7465
• 7475
• 7480
• 7485
• 7490
• 7495
• 7614
• 7615
• 7616
• 7618
• 7714
• 7715
• 7716
• 7718
• 7719
• 7720
• 7722
• 7724
• 7726
• 8450
• 8460
• 8470
• 8480
• 8727
• 8730
• 8732
• 8735
• 8737

1. 1

   Visual Inspection: Locate the X481 engine speed sensor. Disconnect its 2-pin connector and check the pins for corrosion, moisture, or damage.

2. 2

   Resistance Test: With the tractor stopped and the sensor disconnected at ambient temperature, measure the resistance across the sensor's two pins. A healthy sensor should read approximately 450 Ohms (+/- 20 Ohms).

3. 3

   Voltage Test: Check for an alternating voltage (AC) output from the sensor when the gear/engine is turning.

4. 4

   Harness Continuity: Test the wiring harness between the sensor connector and the transmission controller. Check for continuity, proper insulation, and ensure there are no short-circuits to ground or power (+12V).

1. 1

   Preparation

   Park the tractor on a flat surface, turn off the engine, and remove the key.

2. 2

   Access the Sensor

   Locate the X481 engine speed sensor on the engine block/bell housing.

3. 3

   Removal

   Disconnect the 2-pin wiring harness from the sensor. Unbolt the retaining fastener and carefully pull the sensor out of its bore.

4. 4

   Installation

   Lubricate the O-ring on the new genuine Massey Ferguson speed sensor. Insert it into the bore and secure it with the retaining bolt.

5. 5

   Reconnection

   Reconnect the 2-pin wiring harness, ensuring the connector clicks into place and is free of debris.

6. 6

   Clear Codes

   Connect the tractor to the Wintest or EDT diagnostics software to clear the 4.X.91 fault code from the TRANS1 module.

7. 7

   Test Drive

   Operate the tractor to ensure the transmission shifts correctly and the fault code does not return.