Case IH 3108 (DTC 7755) - ECU – Engine Control Unit (ECU) / A-095: Fuel metering unit is shorted to ground at the low side

The Engine Control Unit has detected a short circuit to ground on the low-side control circuit of the fuel metering unit (Y-011).

• MAXXUM T4E
• Case IH Puma Series (165, 180, 195, 210, 225 CVX)
• Case IH 240 Series Axial-Flow Combines
• Case IH Farmall Tractors (40, 45, 50 with Cab and CVT)
• Case IH Magnum Series (310, 335)

1. 1

   Verify Active Status: Use the Electronic Service Tool (EST) to check if the fault is currently active. If it is inactive, the short may be intermittent (e.g., a wire rubbing only when the machine vibrates).

2. 2

   Harness Inspection: Inspect the wiring harness between the ECU (A-095) and the Fuel Metering Unit (Y-011). Look for chafing, melted insulation, or exposed wires that could be grounding out against the engine block or chassis.

3. 3

   Circuit Testing: Disconnect the harness at both the ECU and the metering unit. Use a multimeter to check for continuity to ground on the low-side wire. If continuity to ground exists while disconnected, the harness is shorted.

4. 4

   Component Testing: Check the resistance of the fuel metering unit solenoid terminals. If the solenoid is internally shorted to its own housing, it will trigger this code.

5. 5

   Power Supply Check: Verify battery voltage and check for a faulty charging system or external power supply issues, which can sometimes cause erratic ECU circuit monitoring.

1. 1

   Power Down

   Turn off the machine, remove the key, and disconnect the negative battery cable to prevent electrical damage.

2. 2

   Locate the Component

   Locate the fuel metering unit (Y-011), which is mounted directly onto the Bosch high-pressure fuel injection pump.

3. 3

   Inspect Connectors

   Disconnect the electrical connector from the metering unit. Check the pins for corrosion, moisture, or damage. Clean with contact cleaner if necessary.

4. 4

   Repair Wiring

   If the diagnostic circuit test revealed a short to ground in the harness, trace the wire back to the ECU (A-095). Repair the damaged section of the wire using heat-shrink connectors, or replace the harness section.

5. 5

   Replace the Metering Unit

   If the wiring tests good but the metering unit solenoid is internally shorted, remove the mounting bolts securing the metering unit to the high-pressure pump. Lubricate the O-rings on the new unit with clean diesel fuel and install it. Torque the bolts to OEM specifications.

6. 6

   ECU Verification

   If both the wiring and the metering unit are perfectly functional, the fault may lie within the ECU (A-095) itself (internal hardware failure). In this rare case, the ECU software may need to be re-flashed, or the ECU replaced.

7. 7

   Clear Codes

   Reconnect the battery, connect the EST, clear the fault codes, and run the engine to verify the repair.