John Deere 000627.01 – ECU: Injector Supply Voltage or ECU Power Short

This fault code indicates a critical disruption in the electrical power supply to the engine's fuel injection system. It typically points to either high resistance causing erratic, low, or high voltage to the electronic fuel injectors, or a short to ground in the ECU's unswitched power supply. This loss of power prevents the injectors from operating correctly, resulting in poor engine performance, misfires, or a failure to start.

• 524K
• 624K
• 744K
• 6120
• 6120L
• 6220
• 6220L
• 6320
• 6320L
• 6420
• 6420L
• 6520L
• 7715
• 7815
• 9230
• 9330
• 9430
• 9530
• 9630
• TerraGator 6103

1. 1

   Check the battery and charging system to ensure batteries are fully charged and functioning correctly, as low voltage can trigger injector supply faults

2. 2

   Verify all engine and ECU ground connections, looking for loose or corroded grounds that can create high resistance

3. 3

   Inspect the wiring harness and connectors between the ECU and the fuel injectors for chafing, corrosion, or loose pins, paying close attention to the main ECU connector

4. 4

   Utilize the John Deere Service ADVISOR tool to monitor injector voltage and perform specific diagnostic tests

1. 1

   Address immediate electrical findings

   Rectify any issues found during visual inspection, such as charging a low battery, cleaning corroded terminals, or repairing/replacing damaged sections of the wiring harness.

2. 2

   Test injector circuits

   If wiring appears in good condition, use specialized tools to measure resistance from the ECU connector to the individual injector connectors to check for high resistance.

3. 3

   Isolate and test the ECU

   If the wiring and injector circuits are confirmed to be in good condition and without high resistance, the issue may lie with the Engine Control Unit itself.

4. 4

   Replace faulty components

   Based on diagnostic findings, replace the identified faulty component, which could be a section of the wiring harness, a connector repair kit, or the ECU.