Cylinder 10 Glow Plug Circuit
P0680 indicates a malfunction in the glow plug circuit for cylinder #10, which is the diesel engine preheating system. This code sets when the engine control module detects an open circuit, short, or resistance problem in the glow plug or its wiring that prevents proper engine warm-up, especially in cold conditions.
What You Might Notice
- Check engine light illuminated
- Difficulty starting in cold weather
- Rough idle after cold start
- White smoke from exhaust during cold start
- Engine may not start in freezing temperatures
Most Common Causes
- 1
Faulty glow plug
The glow plug element has failed or burned out, breaking the heating circuit and preventing proper combustion chamber preheating.
- 2
Corroded or loose electrical connection
The glow plug connector or wiring has corrosion, oxidation, or looseness causing poor electrical contact and circuit resistance.
- 3
Broken wiring or harness damage
The glow plug circuit wiring is damaged, cut, or has an open connection preventing current flow to cylinder #10.
- 4
Faulty glow plug relay or controller
The glow plug relay or module controlling power distribution to the glow plugs is defective or not functioning properly.
How to Diagnose It
- 1
Check Faulty glow plug — The glow plug element has failed or burned out, breaking the heating circuit and preventing proper combustion chamber preheating.
- 2
Check Corroded or loose electrical connection — The glow plug connector or wiring has corrosion, oxidation, or looseness causing poor electrical contact and circuit resistance.
- 3
Check Broken wiring or harness damage — The glow plug circuit wiring is damaged, cut, or has an open connection preventing current flow to cylinder #10.
- 4
Check Faulty glow plug relay or controller — The glow plug relay or module controlling power distribution to the glow plugs is defective or not functioning properly.
How to Fix It
- 1
Inspect and clean glow plug connections
Locate the glow plug connector for cylinder #10 and inspect for corrosion, rust, or looseness. Clean the terminal with electrical contact cleaner and reseat the connection firmly.
- 2
Replace faulty glow plug
Remove the glow plug from cylinder #10 using the appropriate socket and wrench, then install a new OEM or equivalent glow plug rated for your diesel engine model.
- 3
Repair or replace damaged wiring
Inspect the glow plug circuit wiring harness for breaks, cuts, or damage. Repair with solder and heat shrink tubing if minor, or replace the entire harness segment if severely damaged.
- 4
Test and replace glow plug relay
Use a multimeter to test the glow plug relay for proper switching and current flow. If faulty, remove and replace the relay with an OEM equivalent for your vehicle.
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