Trouble Code P0683 – Glow Plug Control Module to PCM Communication Circuit Malfunction, Causes and How to Fix

Introduction (What is Error Code P0683?)

The P0683 code is related to the diesel engine starting system, specifically the glow plugs and their control module. This code occurs when the engine control module (PCM) detects a malfunction in the communication circuit with the glow plug control module (GPCM).

Glow plugs play an important role in starting a diesel engine, especially in cold weather. Their job is to preheat the air in the combustion chamber to the temperature required to ignite the fuel. Malfunctions in their system can make it difficult to start the engine, reduce its efficiency, and increase emissions.

Although the P0683 code is not directly related to safety, it can cause problems with starting and running the engine, especially in cold weather.

Meaning and decoding of error code P0683 📊

P0683 – Glow Plug Control Module to PCM Communication Circuit

The P0683 code means that a malfunction has been detected in the communication circuit between the glow plug control module and the PCM. This can be caused by wiring problems, damaged connectors, a faulty GPCM or PCM.

This error occurs mainly in diesel vehicles, especially those where the glow plug control module is located separately from the engine control unit.

Code	Description	Possible problems
P0683	PCM and Glow Plug Module Communication Circuit Malfunction	Broken wiring, corroded contacts, faulty GPCM or PCM

P0683 Error Code Symptoms 🚨 (How to Know There's a Problem?)

• Difficulty starting the engine, especially in cold weather
• Increased starter cranking time
• Increased fuel consumption
• The appearance of black smoke from the exhaust pipe
• Illuminates the Check Engine indicator

💡 Important! Sometimes the only symptom may be the Check Engine light coming on, especially if the engine starts and runs fine in warm weather.

Main causes of error code P0683 ⚠

• Open or short in circuit between PCM and GPCM
• Corrosion or contamination of connector contacts
• Glow Plug Control Module (GPCM) Malfunction
• PCM failure or damage
• Power supply system problems (low voltage, discharged battery)

Possible reason	How to check?
Damaged wiring or contacts	Visual inspection, multimeter check
Faulty GPCM	Diagnostics with a scanner, replacement
Problems with PCM	Checking other systems, testing the unit
Problems with power supply voltage	Measuring voltage at terminals and circuits

How to Diagnose Error Code P0683? 🛠 (Step-by-Step Guide)

✅ Step 1: Connect the OBD2 diagnostic scanner and read all stored errors.

✅ Step 2: Check the battery status and power supply system. Low voltage may cause errors.

✅ Step 3: Inspect the wiring and connectors between the PCM and the glow plug module for signs of corrosion, overheating, or damage.

✅ Step 4: Check the circuit resistance and power to the glow plug module.

✅ Step 5: Replace the faulty GPCM or PCM if necessary.

🛠 Tools you will need:

• OBD2 diagnostic scanner
• Multimeter
• Circuit tester
• Electrical tape, wiring repair tool kit

How to Fix Error Code P0683? 🔧 (Troubleshooting)

Simple methods of elimination ✅

• Cleaning and reconnecting connectors
• Checking and replacing damaged fuses
• Resetting the error via the scanner after troubleshooting

Deep diagnostics and repair ⚙

• Replacing the glow plug control module
• Repair or replacement of wiring harness
• Diagnosing and replacing the PCM if it is faulty

Symptom	Possible Solution
Poor engine starting	Checking and replacing spark plugs/GPCM module
Check Engine No Symptoms	Inspection and cleaning of contacts, error reset
High fuel consumption	Checking the operation of the glow plug system

How to check error code P0683? 🎥

Frequently Asked Questions (FAQ) ❓

Is it okay to drive with a P0683 error code?

Yes, but it is not recommended. The error can cause difficulties when starting the engine, especially in cold weather, and lead to more serious malfunctions.

Could the P0683 code be battery related?

Yes, low supply voltage can cause the glow plug control module to malfunction and cause a communication error with the PCM.

How to reset error code P0683?

The code can be cleared using a diagnostic scanner or by temporarily disconnecting the battery. However, if the fault is not corrected, the error will reappear.

What to do if the error appears only in winter?

This may indicate a problem with the glow plug system, which is especially important in cold conditions. It is recommended to diagnose the GPCM and glow plugs.

Do I need to replace the glow plug control module when I have a P0683 code?

Not necessarily. First, it is worth checking the wiring, connectors and power supply. If the module turns out to be faulty after checking, then it must be replaced.

Error code P0683 in different cars 🚘

P0683 в Ford Super Duty

Especially common in Power Stroke diesel engines, the problem can be caused by a faulty GPCM, which is installed in the engine compartment.

P0683 в Chevrolet Silverado

Diesel Duramax models are prone to problems with glow module contacts and wiring, often requiring harness replacement.

P0683 в Dodge Ram

In Cummins engines, there may be a fault in the control module or an open in the circuit between the PCM and the glow plugs. The problem may be aggravated by corrosion.

P0683 in Volkswagen Touareg

In V6 TDI diesel engines, the fault is most often associated with the glow plug module installed under the intake manifold.

P0683 in BMW X5

On diesel models, the error may be associated with failure of the glow plug unit and malfunctions in the engine control unit.

Related OBD2 Errors 🔗

P0670 – Glow Plug Module Control Circuit

Malfunction in the glow module control circuit. Possible causes:

• Faulty GPCM module
• Open circuit in control circuit

P0671 – Cylinder 1 Glow Plug Circuit

Error of glow plug of the first cylinder. Possible reasons:

• Burnt out glow plug
• Circuit breaks

P0562 – System Voltage Low

Low voltage in the system. Possible causes:

• Discharged battery
• Defective generator

Conclusion (What to do if you have a P0683 error code?) ✅

📌 Short summary: The P0683 code indicates a problem with the circuit between the PCM and the glow plug module. This can affect the starting and operation of a diesel engine.

🚀 Helpful advice: If this error occurs, do not delay diagnostics. Even if the engine starts normally, the malfunction can lead to deterioration of glow plug performance in the future, especially in cold weather.