John Deere 612.04 – Engine Control Unit (ECU): Injector Drive #2 Shorted to Ground

The electrical circuit controlling injection valves 4, 5, and 6 (on 6-cylinder engines) or valves 2 and 3 (on 4-cylinder engines) is shorted to ground. This condition impairs the electrical function of the injectors, causing the engine to misfire, run rough, drop cylinders, and experience significantly reduced performance.

• 5085E
• 5090E
• 5090EL
• 5100E
• 5085M
• 5100M
• 5100MH
• 5100ML
• 5115ML
• 5090M
• 5115M
• 6110M
• 6120M
• 6130M
• 6145M
• 6155M
• 6175M
• 6195M
• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 8310RT
• 8335RT
• 8360RT
• 9470RT
• 9520RT
• 9570RT
• 8245R to 8400R
• 6090 Diesel Engine

1. 1

   Visual Inspection: Examine the injector wiring harness for frayed wires, rubbed-through insulation, or damage that could cause a short to the vehicle's frame or other grounded engine components.

2. 2

   Circuit Testing: Use a multimeter to test the electrical circuits from the ECU to the injector harness to pinpoint the exact location of the short to ground.

3. 3

   ECU Verification: If the wiring harness tests perfectly fine with no shorts found, the internal injector driver within the ECU itself may have failed and is causing the active code.

1. 1

   Repair/Replace Wiring

   If a short is found in the wiring harness during testing, repair the damaged wires or replace the entire injector wiring harness.

2. 2

   Replace the ECU

   If the wiring from the ECU to the injector harness is verified as OK but the tractor is still dropping cylinders, the ECU is the culprit. Remove the faulty ECU, install a new or remanufactured ECU, and flash it with the correct machine payload/software.

3. 3

   Confirm Operation

   After repairs are made, start the engine and ensure that all injectors are operational, receiving the correct voltage, and that the engine is no longer running rough.

4. 4

   Clear Codes

   Clear any stored fault codes and reset the ECU to ensure all systems return to normal functionality.