John Deere 000652.06 – ECU: Injector #2 Circuit Low/Shorted

The Engine Control Unit (ECU) has detected a short circuit or an abnormally low resistance in the electrical circuit for the electronic fuel injector on cylinder number two. The ECU interprets this as the current to the injector increasing too rapidly, which points to an electrical failure rather than a mechanical one. This is common on PowerTech 4.5L and 6.8L diesel engines featuring a Denso High-Pressure Common Rail (HPCR) fuel system.

• 6020
• 6120
• 6220
• 6320
• 6420
• 6520
• 6620
• 6120L
• 6220L
• 6320L
• 6420L
• 6520L
• 6620L
• 6120SE
• 6220SE
• 6320SE
• 6420SE
• 6520SE
• 6620SE
• 7010
• 7610
• 7710
• 7810

1. 1

   Carefully inspect the wiring harness and connectors between the ECU and the number two fuel injector for chafed or melted insulation, corrosion, or loose terminals.

2. 2

   Verify if the fault code is currently active or stored using the tractor's diagnostic display.

3. 3

   Disconnect and reseat the electrical connector at the number two injector and at the ECU to ensure a clean and secure connection.

4. 4

   Disconnect the wiring harness at key points to isolate the segment causing the fault.

5. 5

   Using a digital multimeter, check the continuity of the wires running to injector #2 and test for a short to ground by measuring the resistance between each wire in the injector connector and the chassis ground (a low resistance reading confirms a short).

6. 6

   If the harness is intact, measure the resistance across the two electrical pins of the number two injector and compare it to the manufacturer's specification or other injectors (a significantly lower reading indicates an internal short in the injector).

1. 1

   Prepare machine for repair

   Relieve the fuel system pressure and disconnect the battery ground strap to prevent electrical shorts or injury.

2. 2

   Repair wiring harness

   If diagnostic tests isolated the fault to the wiring harness (e.g., a short to ground), repair the damaged section or replace the harness if the damage is severe.

3. 3

   Replace fuel injector

   If the injector failed the resistance test, thoroughly clean the area around it. Remove the high-pressure fuel line, leak-off line, electrical connector, and hold-down clamp. Extract the injector, clean the bore, and install the new injector with required seals/washers. Reinstall all components and torque to manufacturer specifications.

4. 4

   Program injector calibration code

   If applicable to your system, program the new injector's calibration code into the ECU using a diagnostic tool like John Deere Service ADVISOR to ensure precise control.

5. 5

   Perform final system check

   Reconnect the battery, start the engine, and check for fuel leaks. Clear the fault codes and run the engine to ensure the 000652.06 code does not reappear.