New Holland NH 3085 – Engine Control Module (ECM): Injector Booster Voltage C1 - SOURCE LOW

This fault code indicates that the voltage supplied by the engine control module's internal capacitor (Bank 1 / C1) to fire the fuel injectors is below the minimum required threshold. This typically points to a short circuit to ground in the injector wiring harness for Bank 1, a shorted fuel injector solenoid on that bank, or an internal hardware failure within the Engine Control Unit's injector driver circuit.

• T6 series tractors
• T7 series tractors
• T7000 series tractors
• CR series combines
• CR9090
• CX series combines
• CX8080
• CX8090
• W-Series wheel loaders
• W170C

1. 1

   Visual Inspection: Inspect the engine wiring harness routing from the EDC7 ECU to the engine block/valve cover. Look for chafing, melted insulation, or pinch points that could cause a short to ground.

2. 2

   Connector Check: Disconnect the injector harness connector (Connector 'A') at the EDC7 ECU. Inspect the pins for corrosion, moisture, or bent terminals.

3. 3

   Harness Insulation Test: Using a multimeter, test the Bank 1 injector circuits for continuity to ground. Any continuity to ground indicates a shorted harness.

4. 4

   Injector Resistance Test: Disconnect the electrical leads at each Bank 1 injector. Measure the resistance across the injector solenoid pins. If an injector reads out of specification (or shows continuity to the injector body), the solenoid is internally shorted.

5. 5

   ECU Verification: If the wiring harness and injectors test perfectly, the fault is likely an internal failure of the C1 capacitor inside the Bosch EDC7 ECU.

1. 1

   Turn off the ignition and disconnect the machine's negative battery terminal.

2. 2

   If the diagnostic tests revealed a shorted wiring harness, carefully remove the damaged section of the harness. Splice in a repair pigtail or replace the entire engine injector harness assembly.

3. 3

   If an injector failed the resistance test, remove the valve cover (if applicable to the specific engine model) and remove the high-pressure fuel lines. Extract the faulty injector and install a new one with new copper sealing washers and O-rings.

4. 4

   If the harness and injectors are good, remove the EDC7 Engine Control Unit from its mounting bracket on the side of the engine.

5. 5

   Send the ECU to a specialized commercial vehicle electronics remanufacturer to have the internal injector driver/capacitor repaired, or install a new, dealer-programmed OEM ECU.

6. 6

   Reconnect all electrical connectors (ensuring Connector A is fully seated and locked on the ECU).

7. 7

   Reconnect the battery. If injectors were replaced, bleed the high-pressure fuel system according to the engine service manual.

8. 8

   Connect the New Holland Electronic Service Tool (EST), clear the inactive NH 3085 fault code, and run the engine to verify the repair.