John Deere 612.03 – ECU: There Is A Problem With The Supply Voltage To Injectors 2 And 3 On 4 Cyl, Injectors 4,5 and 6 On 6 Cyl

The electrical circuit controlling the specified fuel injectors has shorted to a power source, causing an abnormally high voltage reading. As a protective reaction, the controller will often limit engine power or shut down the affected injectors, which can lead to engine misfires, rough idling, or a failure to start.

• 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
• 8235R
• 8245R
• 8260R
• 8285R
• 8310R
• 8310RT
• 8335R
• 8335RT
• 8360R
• 8360RT
• 8400R
• 9470RT
• 9520RT
• 9570RT
• 7180
• 7280
• 7380
• 7480
• 7580
• 7780
• 7980
• 4.5L PowerTech engine
• 6.8L (6068) PowerTech engine
• 9.0L (6090) PowerTech engine

1. 1

   Inspect Wiring and Connectors: Examine the fuel injector wiring harness closely for any signs of insulation wear, damage, or melting that could cause a short to a voltage source.

2. 2

   Test Electrical Circuits: Use a multimeter to test the injector circuits (specifically the wiring going to injectors 2 and 3 on 4-cylinder engines, or 4, 5, and 6 on 6-cylinder engines) to pinpoint the exact location of the short to power.

3. 3

   Confirm Injector Operation: Verify that the injectors themselves have not been internally shorted or damaged by the voltage spike.

1. 1

   Disconnect the battery

   Disconnect the battery to prevent further electrical damage during repair.

2. 2

   Locate the damaged section of the injector wiring harness

   Locate the damaged section of the injector wiring harness identified during the diagnostic phase.

3. 3

   Repair or replace the fuel injector wiring harness

   If the damage is localized, repair the compromised wiring and properly insulate it. If the harness is severely degraded or melted, replace the entire fuel injector wiring harness.

4. 4

   Replace the affected electronic fuel injector

   If an injector was internally damaged by the short, remove the injector clamp, fuel delivery line, and terminal nuts, then replace the affected electronic fuel injector.

5. 5

   Reconnect the battery and verify voltage

   Reconnect the battery and ensure all injectors are receiving the correct voltage.

6. 6

   Clear diagnostic fault codes

   Clear the diagnostic fault codes and reset the ECU to restore normal engine operation and remove any power derates.