Massey Ferguson D157 – Instrument Panel / Dashboard: Engine speed sensor - No electrical signal

The tractor's control system is failing to receive the RPM signal from the engine speed sensor (X25).

• MF 8600
• MF 8650
• MF 8660
• MF 8670
• MF 8680
• MF 8690
• MF 8450
• MF 8460
• MF 8470
• MF 8480
• 5400 Series
• 5445
• 5455
• 5460
• 5465
• 6400 Series
• 6445
• 6455
• 6480
• 6499
• 7400 Series
• 7600 Series
• 8400 Series
• 8600 Series
• 8670
• 8690

1. 1

   Do not immediately replace the sensor. Replacing sensors without first performing diagnostic tests will result in denied warranty claims.

2. 2

   Connect the tractor to Massey Ferguson's Wintest software to monitor the live data feed from the X25 engine speed sensor and verify if the signal is genuinely dropping out.

3. 3

   Check the wiring harness and connector at the X25 sensor for breaks, corrosion, or loose pins that could cause a 'No electrical signal' condition.

4. 4

   Verify if Autotronic 4 code T4144 is also active, which confirms the transmission ECU is also missing the engine RPM data.

1. 1

   Locate the Sensor

   The engine speed sensor reads off the engine/flywheel. Depending on your specific model (e.g., MF 6499), access can be highly restricted. In some cases, you may need to remove a rear tire/wheel to gain adequate access to the sensor housing.

2. 2

   Remove the Sensor

   Disconnect the electrical connector. Remove the retaining bolt. Caution: Be prepared for seized bolts due to the sensor's location and exposure to field debris.

3. 3

   Install the New Part

   Clean the mounting port, insert the new OEM speed sensor, and secure the retaining bolt. Reconnect the wiring harness.

4. 4

   Clear Codes

   Turn on the battery power. The system is designed to clear the 'No electrical signal' error automatically after one or two successful ignition cycles once the signal is restored. Use Wintest to clear any residual historical codes.