New Holland ENG 3139 – Engine Control Unit (ECU): Fuel Metering Unit: Metering Unit Signal Range Check - Signal Too High

The control module is reading a voltage from the metering unit circuit that exceeds the maximum expected threshold, indicating an open circuit, a short to battery voltage in the wiring harness, or an internal failure within the metering unit.

• New Holland T5 Series Tractors (T5.95, T5.105, T5.115)
• New Holland T8 Series Tractors
• New Holland Skid Steer Loaders (SSL) and Compact Track Loaders (CTL) equipped with the F5C engine

1. 1

   Inspect the wiring harness and connectors between the Engine ECU and the Fuel Metering Unit for chafing, breaks, or severe corrosion

2. 2

   Disconnect the electrical connector at the Fuel Metering Unit and measure resistance across the solenoid pins (an 'OL' or infinite reading confirms internal coil failure)

3. 3

   Check the wiring harness for continuity from the ECU connector pins to the metering unit connector pins to rule out a broken wire

4. 4

   With the key ON (engine off), test the signal wire at the metering unit connector for a short to battery voltage

1. 1

   Turn off machine and disconnect battery

   Turn off the machine, remove the key, and disconnect the battery to prevent electrical shorts.

2. 2

   Locate Fuel Metering Unit

   Locate the Fuel Metering Unit on the back or side of the Bosch high-pressure fuel injection pump.

3. 3

   Disconnect electrical connector

   Disconnect the electrical connector from the unit.

4. 4

   Clean area around metering unit

   Thoroughly clean the area around the metering unit with brake cleaner and compressed air. Any dirt entering the high-pressure pump during this process can cause catastrophic fuel system failure.

5. 5

   Remove mounting fasteners

   Remove the mounting fasteners (typically Torx screws) securing the metering unit to the pump housing.

6. 6

   Remove old metering unit

   Carefully pull the old metering unit straight out of the pump.

7. 7

   Lubricate O-rings on new unit

   Lubricate the O-rings on the new Fuel Metering Unit with clean diesel fuel or assembly lube. Do not install it dry, as this can tear the O-rings.

8. 8

   Install new metering unit

   Insert the new unit into the pump and tighten the mounting screws to the manufacturer's specified torque.

9. 9

   Reconnect electrical connector

   Reconnect the electrical connector.

10. 10

    Reconnect battery

    Reconnect the battery.

11. 11

    Clear fault codes

    Connect a diagnostic service tool (such as CNH EST) to clear the inactive fault codes. Some EDC systems may require a reset of learned parameters after replacing the metering unit.

12. 12

    Test engine operation

    Start the engine, check for fuel leaks, and verify that the fault code does not return.