John Deere 676.06 – Engine Control Unit (ECU): Glow Plug Relay Output Out of Range High

The current draw in the starting aid (glow plug) coil/relay circuit is higher than the Engine Control Unit (ECU) expects. This typically indicates a short to ground or abnormally low resistance in the glow plug relay drive circuit.

• 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
• 318D
• 320D
• 325
• 328
• 318E
• 320E
• 326D
• 332D
• 210G
• 330LC-8B
• 17D
• 26G
• 35D
• 50D
• 1023E
• 1025R
• 1026R
• 2025R
• 2305
• 3025E

1. 1

   Cycle the power to the tractor/machine to verify if the code remains active.

2. 2

   Locate and remove the main glow plug fuse (e.g., 50-amp fuse F63 on excavator models) and check for continuity. A blown fuse often accompanies a short-to-ground.

3. 3

   Inspect the wiring harness between the ECU and the glow plug relay (often labeled K03). Look for rubbed-through insulation, pinched wires, or melted connectors that would cause a short to ground.

4. 4

   Perform a relay circuit test on the glow plug relay. Check the resistance across the relay coil pins; if the resistance is near zero, the relay is internally shorted.

1. 1

   Disconnect Power

   Turn the ignition off and disconnect the negative battery cable to prevent electrical spikes.

2. 2

   Locate the Relay

   Find the glow plug relay. Depending on the machine, this may be located in the main fuse panel (like on the 318D skid steers) or mounted near the engine block/firewall.

3. 3

   Repair Wiring (If Applicable)

   If the diagnostic checks revealed a short to ground in the wiring harness, repair the damaged wire using heat-shrink connectors and re-loom the harness.

4. 4

   Replace the Relay

   If the wiring is intact but the relay failed the resistance test, unplug the old relay and plug in the replacement.

5. 5

   Replace the Fuse

   If the high-current event blew the glow plug fuse, install a new fuse of the exact same amperage rating.

6. 6

   Clear Codes and Test

   Reconnect the battery, turn the key to the ON position (engine off), and verify the glow plug indicator illuminates normally without triggering the 000676.06 code. Start the engine to confirm the repair.