Case IH 3107 (F-5447-03) - ECU – Engine Control Unit (ECU): Fuel metering unit is shorted to battery voltage at the low side

The engine control module has detected a short circuit to a battery voltage source on the ground/low-side circuit of the fuel metering unit (MPROP/fuel pressure control valve). Because of this short, the controller cannot properly pulse-width modulate (PWM) the valve, leading to a loss of fuel pressure control.

• VESTRUM CVX
• Magnum MX210
• Magnum MX230
• Magnum MX255
• Magnum MX285
• Magnum 235-340 Series 4
• Steiger 350-600
• Puma 165
• Puma 180
• Puma 195
• Puma 210
• Puma 225 CVX
• Farmall CVT 40
• Farmall CVT 45
• Farmall CVT 50
• 240 Series Axial-Flow Combines
• A8000 Sugar Cane Harvester
• A8800 Sugar Cane Harvester

1. 1

   Check for External Power Sources: Check if the tractor's battery power supply is currently connected to an external power supply (such as a battery charger or jump box). If connected, disconnect it and test the system for normal operation.

2. 2

   Verify Active Faults: Use the Electronic Service Tool (EST) to confirm if the fault is currently active.

3. 3

   Harness Inspection: Inspect the engine wiring harness between the ECU and the fuel metering unit. Look for chafed wires, melted insulation, or pinched harnesses that could cause the low-side wire to short against a 12V/24V power source.

4. 4

   Isolate the Component: Disconnect the electrical connector at the fuel metering unit. Use a multimeter to test the harness side for voltage on the ground circuit. If voltage is present, the harness is shorted; if the harness tests fine, the internal solenoid of the fuel metering unit has failed and is shorting out.

1. 1

   Preparation

   Turn off the machine, remove the key, and disconnect the negative battery cable to prevent electrical damage. Clean the area around the high-pressure fuel pump (typically a Bosch CP3 pump) thoroughly to prevent dirt from entering the fuel system.

2. 2

   Disconnect

   Unplug the electrical connector from the fuel metering unit located on the high-pressure pump.

3. 3

   Removal

   Remove the mounting fasteners (usually Torx or Allen bolts) securing the metering unit to the pump housing. Carefully pull the unit straight out.

4. 4

   Lubrication

   Coat the O-rings on the new fuel metering unit with clean diesel fuel or a manufacturer-approved assembly lubricant to prevent tearing during installation.

5. 5

   Installation

   Insert the new fuel metering unit into the pump housing. Install and torque the mounting bolts to the OEM specification.

6. 6

   Reassembly

   Reconnect the electrical connector and the battery.

7. 7

   Clear and Test

   Connect the EST to clear the inactive 3107 / 6655 fault code. Start the engine, check for fuel leaks around the pump, and verify that the engine operates smoothly without derating or throwing the code again.