Massey Ferguson D128 – Dash / Instrument Panel: Issue With Signal Voltage From Fuel Level Sensor Low Voltage

The voltage signal returning from the fuel tank's sending unit to the instrument cluster has dropped below the minimum expected threshold. This usually points to a short circuit to ground in the sensor wiring, an open circuit, or a completely failed potentiometer inside the fuel level sensor.

• MF 8650
• MF 8680
• Interim Tier 4 (2012-2015)
• 7615
• 5613
• MF 8480
• MF 8450
• 7616
• 7618
• 5608
• 7619
• 7626
• MF 8660
• 7624
• MF 8690
• 7614
• MF 8470
• 5610
• 7620
• MF 8600
• MF 8460
• MF 8670
• 5612
• 7622
• 5611
• 5609
• MF 8600 Series
• MF 7600 Series
• MF 6400 Series
• MF 6600 Series
• MF 6700 Series
• MF 7400 Series
• MF 7700 Series
• MF 300 Series
• MF 4200 Series
• MF 4300 Series
• MF 5400 Series
• MF 6465
• MF 6475
• MF 6480
• MF 7465
• MF 7480
• Tractors equipped with Dyna-4, Dyna-6, and Dyna-VT transmissions

1. 1

   Check the Wiring Harness: Inspect the wiring from the instrument panel (specifically the signal wire) to the fuel level sensor. Look for chafing, pinched wires, or areas where the wire might be shorting directly to the tractor's chassis (ground).

2. 2

   Inspect the Connector: Check the electrical plug at the fuel sending unit on top of the fuel tank. Look for corrosion, moisture, or loose pins that could cause a drop in signal voltage.

3. 3

   Test the Sending Unit: Disconnect the sensor and use a multimeter to measure the resistance (ohms) across the sensor's terminals while manually moving the float arm (if accessible) or checking static resistance. If it reads infinite resistance (open) or zero resistance (dead short), the sensor is faulty.

4. 4

   Check Fuses: Verify that the fuses related to the instrument cluster and fuel gauge circuit are intact.

1. 1

   Preparation

   Turn off the tractor, remove the key, and disconnect the negative battery terminal to prevent electrical shorts.

2. 2

   Access the Sensor

   Locate the fuel sending unit, which is typically mounted on the top of the fuel tank. Clean the area around the sensor thoroughly to prevent dirt or debris from falling into the diesel tank.

3. 3

   Disconnect

   Unplug the electrical connector from the sensor.

4. 4

   Removal

   Remove the mounting bolts or the retaining ring securing the sensor to the tank. Carefully pull the old sensor and float arm assembly straight up and out of the tank.

5. 5

   Installation

   Insert the new fuel level sensor into the tank, ensuring you use a new rubber gasket/O-ring to prevent fuel leaks. Secure it with the mounting bolts or retaining ring.

6. 6

   Reassembly

   Reconnect the electrical plug to the new sensor and reconnect the battery.

7. 7

   Verification

   Turn the ignition on. The fuel gauge should now register the correct fuel level. Use an OBD scanner or the tractor's onboard diagnostic menu to clear the D128 fault code.