Case IH 3079 (DTC 6426) - ECU – Engine Control Unit (ECU): Short circuit error of injector in cylinder 3

The engine controller has detected abnormally high current or a short to ground/power in the electrical circuit responsible for firing the fuel injector on the third cylinder.

• MAXXUM T4E
• Axial-Flow Combines (240 Series, 7230, 8230, 9230)
• Puma Series Tractors
• A8000 Sugar Cane Harvesters
• A8800 Sugar Cane Harvesters

1. 1

   Check for related fault code 3210 (DTC 7116) - 'Injection bank 1 short circuit failure'. A short in one injector can affect all injectors on the same bank.

2. 2

   Visually inspect the engine wiring harness leading to the cylinder 3 injector for chafing, melted insulation, or pinched wires.

3. 3

   Disconnect the harness from the ECU and the injector. Use a multimeter to test for a short circuit to ground or a short between the two injector wires.

4. 4

   Measure the resistance across the terminals of the cylinder 3 injector solenoid. If the resistance is out of the specified OEM range, the injector has an internal short.

1. 1

   Disconnect power

   Turn off the machine and disconnect the battery to prevent electrical damage during the repair.

2. 2

   Resolve wiring issues

   If the diagnostic tests indicated a short circuit in the wiring, use the service manual wiring diagram to locate the shorted conductor. Repair the damaged section of the wire harness or replace the harness entirely if the damage is extensive.

3. 3

   Replace the injector

   If the wiring is intact but the injector solenoid failed the resistance test, remove the valve cover (if the injectors are under the cover, depending on the engine model) and extract the cylinder 3 fuel injector.

4. 4

   Install new injector

   Install the replacement injector using new O-rings and seals. Torque the hold-down clamp to the OEM specification.

5. 5

   Reassemble and clear codes

   Reconnect the wiring harness, reassemble any removed components, and reconnect the battery. Use a diagnostic tool to clear the 3079 (DTC 6426) fault code and run the engine to verify the repair.