Case IH 3108 (F-5447-04) - ECU – Engine Controller / Engine Control Unit (ECU / EDC): Fuel metering unit is shorted to ground at the low side

The ECU detects that the low-side control circuit for the fuel metering unit solenoid has a short circuit to ground, which prevents the ECU from properly regulating fuel pressure.

• VESTRUM CVX
• 240 Series Axial-Flow Combines
• Magnum Series (235–340 Series 4)
• Puma Series (165, 180, 195, 210, 225 CVX)
• Farmall
• Case 580 Super N backhoes
• Skid Steer Loaders (SSL)
• Compact Track Loaders (CTL)

1. 1

   Test the wiring harness between the ECU and the fuel metering unit for continuity to chassis ground on the low-side circuit wire (most common cause).

2. 2

   Inspect ECU to metering unit connections for loose contacts, moisture, or corrosion at the electrical connector and ECU pins.

3. 3

   Measure the internal resistance of the fuel metering unit's solenoid coil to determine if the short to ground is internal to the valve itself.

4. 4

   Inspect Main Relay 1 (High Pressure Pump relay) to ensure it is functioning and its wiring is not compromised.

1. 1

   Safety preparation

   Turn off the machine, remove the key, and disconnect the negative battery terminal.

2. 2

   Inspect the harness

   Trace the wiring harness from the fuel metering unit (located on the high-pressure fuel pump) back to the Engine ECU. Look for areas where the wire loom may have rubbed against the engine block or frame, causing the insulation to chafe and short to ground.

3. 3

   Repair wiring

   If a short is found in the wiring harness, repair the damaged section using proper soldering and heat-shrink techniques, or replace the affected harness section.

4. 4

   Replace fuel metering unit

   If an internal short is found during resistance testing: Clean the area around the high-pressure fuel pump thoroughly. Disconnect the electrical connector, remove the mounting screws, and carefully pull the metering unit out. Lubricate the O-rings on the new unit with clean diesel fuel, insert it into the pump, and torque the mounting screws to the manufacturer's specification.

5. 5

   Reassemble and clear codes

   Reconnect the electrical connector and the battery. Use a diagnostic service tool to clear the 3108 (F-5447-04) fault code from the ECU. Run the engine and verify that the code does not return and that fuel rail pressure is within normal parameters.