Massey Ferguson 4: Engine Speed Pickup Fault

The fault code indicates an issue with the engine speed pickup, which is responsible for monitoring the engine's rotational speed. This component may be malfunctioning or not providing accurate signals to the controller. A malfunction can lead to incorrect dashboard readings, unexpected PTO disengagement, or the system defaulting to a set value of 2250 rpm.

• 5400 Series
• 6400 Series
• 6480
• 6499
• 7600 Series
• 5710SL
• 5711SL
• 5712SL
• 5713SL
• 5470
• 5480
• 6460
• 6470
• 6718
• 7485
• 7490
• 7495
• 7714
• 7715
• 7726
• 8450
• 32
• 34
• 38

1. 1

   Visually inspect the sensor for any visible damage and inspect the wiring and connectors for corrosion, looseness, or damage. A bad connection can mimic a faulty sensor.

2. 2

   Perform a resistance test by disconnecting the sensor and measuring the resistance across its terminals using a multimeter. Expected resistance is approximately 450 ohms +/- 20 ohms at room temperature, or around 1,000 ohms for certain two-wire sensors. An open circuit or a reading far outside the specified range indicates a faulty sensor.

3. 3

   Check the continuity of the signal and ground wires in the harness between the sensor connector and the control module to rule out a break in the wiring.

4. 4

   For active/3-wire sensors, perform a voltage test with the ignition on to check for power at the sensor's connector (typically a 5V or 12V reference voltage).

5. 5

   Perform a signal output test: for magnetic (2-wire) sensors, check for a small AC voltage signal while the engine is cranking or running; for Hall-effect (3-wire) sensors, look for a pulsing DC voltage.

6. 6

   Check the sensor gap to ensure the clearance between the sensor and the gear it reads is within tolerance, which is often between 0.015 and 0.025 inches.

1. 1

   Disconnect the Battery

   For safety, always disconnect the battery before starting work on the electrical system.

2. 2

   Locate and Remove the Sensor

   The engine speed sensor's location can vary. On some models, like the MF 6499, it is located on top of the rear axle housing, reading a gear that drives the hydraulic pump.

3. 3

   Install the New Sensor

   Screw the new sensor in until it makes contact with the gear.

4. 4

   Set the Air Gap

   After the sensor touches the gear, back it off by 3/4 of a turn to set the correct air gap.

5. 5

   Tighten the Lock Nut

   Secure the sensor by tightening the counter-nut to the specified torque, which may be around 6 Nm.

6. 6

   Apply Sealant

   It is recommended to apply a sealant like Loctite 5922 to the sensor threads.

7. 7

   Reconnect and Test

   Reconnect the electrical connector and the battery, then start the tractor to ensure the fault is cleared and the RPM reading is stable.