John Deere 656.05 – Engine Control Unit (ECU): Injector Number 6 Circuit Has High Resistance

The Engine Control Unit has detected that the electrical current flowing to the fuel injector on cylinder #6 is lower than expected. This condition is typically caused by an open circuit in the wiring harness, a loose connection, or a failure of the internal injector solenoid coil.

• 6110M
• 6120M
• 6130M
• 6145M
• 6155M
• 6175M
• 6195M
• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 7610
• 7710
• 7810
• 7720
• 7820
• 7920
• 9200
• 9300
• 9400
• 7R/8R series
• 444J
• 544J
• 624J
• 644K
• 724K
• 750J
• 850J
• 4930
• 350GLC
• 380GLC

1. 1

   Cycle the Power: Restart the engine to verify if the active Service Code reappears. Sometimes, resetting the communication messages clears intermittent faults.

2. 2

   Wiring Harness Inspection: Check the wiring harness between the Engine ECU and the cylinder #6 injector for open circuits, chafing, or disconnected plugs.

3. 3

   Connector Pin Test: Check the connector terminals at the injector and ECU. Do not force standard multimeter probes into the connector terminals, as this will cause damage and spread the pins. Use a proper connector adapter test kit (like John Deere tool JT07328) to take measurements.

4. 4

   Solenoid Resistance Test: Measure the resistance of the cylinder #6 injector solenoid directly to determine if the coil is open or out of specification.

1. 1

   Safety First

   Turn off the engine. If working on an HPCR engine, relieve any high-pressure fluid in the fuel lines before disconnecting them to prevent injection injuries.

2. 2

   Harness Repair

   If the diagnostic checks reveal a broken wire or damaged connector leading to cylinder #6, repair or replace the engine wiring harness.

3. 3

   Access the Injector

   If the wiring is intact, the fault is a failed injector solenoid. Remove the valve cover (if the engine uses under-cover EUIs) or clear the top-end components to access the common rail injector for cylinder #6.

4. 4

   Remove the Faulty Injector

   Disconnect the electrical connector from the #6 injector. Remove the hold-down clamp and extract the faulty injector.

5. 5

   Install the New Injector

   Install the replacement injector using new O-rings and sealing washers. Torque the hold-down clamp to OEM specifications.

6. 6

   Reassembly

   Reconnect the electrical connector and reassemble the fuel lines and valve cover.

7. 7

   ECU Calibration

   Depending on the engine model (e.g., 9.0L HPCR), you must enter the new injector's trim/calibration code into the Engine ECU using a diagnostic tool so the ECU can properly fuel the cylinder.

8. 8

   Clear Codes

   Clear the fault codes and run the engine to verify the repair.