P0683 Code: Step-by-Step Repair

The P0683 trouble code is a diagnostic trouble code (DTC) that indicates an issue with the glow plug preheating system in diesel engines. Specifically, it refers to a malfunction in the communication circuit between the glow plug control module and the powertrain control module (PCM). This code is crucial for diesel engine operation, especially in cold weather, as it impacts the engine’s ability to start effectively. Understanding this code is essential for vehicle owners and DIY mechanics looking to troubleshoot and repair related issues.

Symptoms of P0683 Code

When the P0683 code is triggered, drivers may notice several symptoms that indicate a problem with the glow plug system:

• Difficulty Starting: The engine may struggle to start, particularly in cold conditions.
• Prolonged Cranking: It may take longer than usual for the engine to crank and start.
• Check Engine Light: The dashboard check engine light (MIL) will illuminate.
• Rough Idle: The engine may run roughly or stall when cold due to incomplete combustion.
• Excessive Exhaust Smoke: Increased white or gray smoke from the exhaust during starting attempts.

Technical Explanation of P0683 Code

The P0683 code signifies a communication issue between the glow plug control module and the PCM. In diesel engines, glow plugs are essential for preheating air in the combustion chamber, especially under low-temperature conditions. When the PCM detects that it cannot properly communicate with the glow plug control module, it sets this trouble code.

Step-by-Step Diagnosis

To diagnose a P0683 code effectively, follow these steps:

1. Use an OBD-II Scanner: Confirm the presence of the P0683 code and check for any additional trouble codes that may provide context.
2. Visual Inspection: Inspect the glow plug relay, wiring, and connectors for signs of damage, corrosion, or loose connections.
3. Test Glow Plug Relay: Using a multimeter, check if the relay is functioning correctly. The relay should close when activated by the PCM.
4. Check Glow Plugs: Measure resistance across each glow plug with a multimeter. A reading outside of normal specifications indicates a faulty glow plug.
5. Inspect Wiring Harness: Look for damaged wires or connectors between the PCM and the glow plug control module.
6. Test PCM Communication: Check if the PCM is sending signals to the glow plug control module using appropriate diagnostic tools.

Solution Methods for P0683 Code

Once you have diagnosed the issue causing the P0683 code, you can proceed with repairs:

1. Replace Faulty Glow Plug Relay

• Symptoms: If you find that the relay is not functioning properly.
• Steps:
• Disconnect battery power.
• Remove and replace the faulty relay.
• Reconnect battery and test system functionality.
• Cost Estimate: Replacement relays typically range from $20 to $50 plus labor if performed by a mechanic.

2. Repair or Replace Damaged Wiring

• Symptoms: Visible damage or corrosion on wiring.
• Steps:
• Inspect wiring harness thoroughly.
• Repair any damaged sections using heat-shrink tubing or electrical tape.
• Replace entire sections of wiring if necessary.
• Cost Estimate: Depending on labor rates, costs can vary widely but expect around $100 to $300 for repairs involving significant wiring work.

3. Replace Faulty Glow Plugs

• Symptoms: Resistance tests indicate one or more plugs are faulty.
• Steps:
• Disconnect battery power.
• Remove faulty glow plugs using a socket wrench.
• Install new glow plugs and reconnect battery.
• Cost Estimate: Glow plugs can range from $10 to $30 each; labor costs will add another $100 to $200 depending on accessibility.

4. Check and Replace Blown Fuses

• Symptoms: If fuses are blown in circuits related to glow plugs.
• Steps:
• Locate fuse box and identify relevant fuses.
• Replace any blown fuses with appropriate amperage fuses.
• Cost Estimate: Fuses are inexpensive, typically under $5 each; labor cost is minimal if done DIY.

5. Replace Faulty PCM

• Symptoms: If all other components are functioning but communication issues persist.
• Steps:
• Use diagnostic tools to confirm PCM failure.
• Replace with a compatible unit and reprogram if necessary.
• Cost Estimate: Replacement PCMs can cost between $200 and $800 depending on make/model; professional installation may add additional labor costs.

Warnings and Recommendations

When dealing with electrical systems in vehicles, safety is paramount:

• Always disconnect battery power before working on electrical components to avoid shocks or shorts.
• Use appropriate tools such as multimeters for testing circuits safely.
• If unsure about any diagnosis or repair steps, consult with a professional mechanic to prevent further damage or safety hazards.

Closing Paragraph

The P0683 trouble code serves as an important indicator of issues within diesel engine preheating systems. By understanding its implications and following proper diagnostic procedures, vehicle owners can effectively address this error code. Whether through DIY repairs or seeking professional assistance, timely attention to this code can ensure reliable engine performance and prevent further complications in your vehicle’s operation.

Frequently Asked Questions About P0683

• What does P0683 mean?
  P0683 indicates a communication error between the glow plug control module and the powertrain control module.
• What symptoms will I notice with a P0683 code?
  You may experience difficulty starting your diesel engine, prolonged cranking times, and an illuminated check engine light.
• Can I drive my vehicle with a P0683 code?
  While it may be possible to drive short distances, it’s advisable to address this issue promptly as it can lead to further engine problems.
• How do I reset a P0683 code?
  You can reset it by disconnecting your vehicle’s battery for about 15 minutes or using an OBD-II scanner after repairs are made.
• Is there a risk of damaging my engine if I ignore this code?
  Yes, ignoring this issue can lead to poor engine performance and potential damage due to incomplete combustion.
• What tools do I need to diagnose a P0683 code?
  A basic toolkit including an OBD-II scanner, multimeter, socket set, and possibly wire repair tools will be necessary.
• Should I consult a mechanic for a P0683 error?
  If you’re not comfortable diagnosing or repairing electrical issues yourself, it’s best to seek professional help.
• Are all vehicles affected by P0683?
  P0683 is a generic OBD-II code applicable across many diesel vehicles manufactured since 1996.