Case IH 3912 – Engine Control Module (ECM) / EDC: Fuel metering unit is shorted to ground at the high side.

The system has detected that the electrical circuit supplying power (the "high side") to the Fuel Metering Unit (also known as the MPROP or fuel pressure control valve) has a short circuit to ground. This prevents the valve from properly regulating the fuel volume entering the high-pressure fuel pump, which can lead to engine power loss, failure to start, or limp mode.

• Steiger T4B
• 240 Series Axial-Flow (7230, 8230, 9230)
• Magnum 235 - 340 (Series 4)
• Puma Series
• Steiger / Quadtrac
• A8000 / A8800 Sugar Cane Harvesters

1. 1

   Check if the tractor's battery power supply has been connected to an external power supply (like a jump box or charger). If an external power supply is connected, disconnect it and test the system for normal operation before tearing into the wiring.

2. 2

   Verify if other fuel metering codes are present, such as 3137 (DTC 5255 - open load), 3910 (DTC 4155 - intermittent connection), or 3735 (DTC 8355 - over-temperature).

3. 3

   Visually inspect the wiring harness between the Engine Control Module (ECM) and the Fuel Metering Unit on the high-pressure pump for chafing, melting, or pinched wires.

1. 1

   Disconnect Power

   Turn off the machine and disconnect any external power supplies or battery chargers.

2. 2

   Locate the Component

   Locate the Fuel Metering Unit, which is bolted directly to the high-pressure fuel injection pump.

3. 3

   Isolate the Circuit

   Disconnect the electrical connector at the Fuel Metering Unit and the corresponding connector at the ECM.

4. 4

   Test the Wiring

   Using a digital multimeter, measure the continuity between the high-side supply wire (Pin 1/Power) and a known good chassis ground.

5. 5

   Repair the Harness

   If continuity to ground is present while both ends are unplugged, the wiring harness is shorted. Locate the damaged section of the harness and repair or replace the affected wires.

6. 6

   Test the Metering Unit

   If the wiring harness tests good (no short to ground), the internal solenoid coil of the Fuel Metering Unit itself has likely shorted to its own metal housing.

7. 7

   Replace and Clear

   If the unit is internally shorted, replace the Fuel Metering Unit. Reconnect all harnesses, clear the fault codes via the diagnostic menu or service tool, and run the engine to verify the repair.