John Deere 676.05 – ECU: Cold Start Aid Circuit Has High Resistance / Glow Plug Relay Voltage is Too Low

The engine controller detects that the cold start aid relay's output is passive (low or open circuit) when the controller is actively commanding the relay to energize. This prevents the glow plugs or intake manifold heater from receiving the voltage needed to warm the engine for a cold start.

• 5065M
• 5075M
• 5085M
• 5095M
• 5095MH
• 5105M
• 5015ML
• 5100M
• 5115ML
• 6230
• 6330
• 6430
• 7630
• 7730
• 7810
• 7830
• 7930
• 748H Skidders
• 210G/GLC Excavators
• PowerTech 2.4L
• PowerTech 3.0L
• PowerTech 4.5L
• PowerTech 6.8L
• PowerTech 9.0L

1. 1

   Identify the glow plug/cold start relay (often K03 or K22) in the main fuse and relay load center.

2. 2

   Perform a relay circuit test to check the coil for an open circuit and ensure load contacts have continuity when energized.

3. 3

   Inspect wiring harness connectors between the ECU and the relay (e.g., ICC-J3) for backed-out pins, corrosion, or moisture.

4. 4

   Use a multimeter to check for high resistance or an open short on the power supply line feeding the relay and the output line to the glow plugs.

1. 1

   Park the machine safely, lower all equipment to the ground, stop the engine, and remove the key.

   Park the machine safely, lower all equipment to the ground, stop the engine, and remove the key.

2. 2

   Disconnect the battery ground strap to prevent electrical shorts during repair.

   Disconnect the battery ground strap to prevent electrical shorts during repair.

3. 3

   Remove the cover to access the main fuse and relay load center.

   Remove the cover to access the main fuse and relay load center.

4. 4

   Locate the Cold Start/Glow Plug Relay (e.g., K03 or K22) using the reference label provided under the cover.

   Locate the Cold Start/Glow Plug Relay (e.g., K03 or K22) using the reference label provided under the cover.

5. 5

   Pull the relay and inspect the socket for melted plastic, heat damage, or corroded terminals. Clean the terminals with electrical contact cleaner if necessary.

   Pull the relay and inspect the socket for melted plastic, heat damage, or corroded terminals. Clean the terminals with electrical contact cleaner if necessary.

6. 6

   Swap the relay with a known-good relay of the exact same amperage and pinout (such as a work light relay) to see if the fault code clears.

   Swap the relay with a known-good relay of the exact same amperage and pinout (such as a work light relay) to see if the fault code clears.

7. 7

   If the relay is confirmed dead, install a new OEM replacement relay.

   If the relay is confirmed dead, install a new OEM replacement relay.

8. 8

   If the relay is functional but the code persists, trace the wiring harness from the relay block to the ECU to repair any broken wires causing the open circuit.

   If the relay is functional but the code persists, trace the wiring harness from the relay block to the ECU to repair any broken wires causing the open circuit.

9. 9

   Reconnect the battery, cycle the key to trigger the cold start sequence, and verify the ECU 000676.05 code is no longer active.

   Reconnect the battery, cycle the key to trigger the cold start sequence, and verify the ECU 000676.05 code is no longer active.