AutoCodes – Chevrolet – P0678 2017 Chevrolet Silverado

P0678 2017 Chevrolet Silverado Code - Cylinder 8 Glow Plug Circuit Fault

Quick Answer

n the diesel engine, air alone is compressed in the cylinder. Common causes include Faulty cylinder #8 glow plug, Cylinder #8 glow plug harness is open or shorted, Cylinder #8 glow plug circuit poor electrical connection. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: P0678 2017 Chevrolet Silverado indicates Cylinder 8 Glow Plug Circuit Fault.
Common causes: Common causes include Faulty cylinder #8 glow plug, Cylinder #8 glow plug harness is open or shorted, Cylinder #8 glow plug circuit poor electrical connection.
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

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Code Popularity 288

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

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Table of contents Created and updated by William Orellana on Mar 24, 2024

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P0678 2017 Chevrolet Silverado Description

n the diesel engine, air alone is compressed in the cylinder. Then, after the air has been compressed, a charge of fuel is sprayed into the cylinder and ignition occurs, due to the heat of compression. Eight glow plugs are used as an aid to starting.
Control of the glow plugs is accomplished by the Glow Plug Control Module. The nominal voltage for the glow plugs is 5.4 volts. When the ignition is turned On, the Glow Plug Control Module applies 7.2 V for 2.2 s, then 5.7 V for 0.8 s, and then 5.4 V until 1200°C (2192°F) is reached. The maximum voltage of the system is 10 V. While the engine is running the voltage will vary between 4.7 - 10 V when in closed loop control to maintain a glow plug temperature that ranges from 1150° - 1180°C (2102° - 2156°F). The temperature and the power consumption are controlled between the Engine Control Module (ECM) and the Glow Plug Control Module within a wide range to suit the engine's pre-heating requirements. Each glow plug is energized individually. This capability yields more optimum heat times for the glow plugs, thus pre - glow times can be kept to a minimum for a short wait to crank times and maximum glow plug durability.

OBDII Code P0678 2017 Chevrolet Silverado - Cylinder 8 Glow Plug Circuit Fault - AutoCodes.com — P0678 2017 Chevrolet Silverado Code - Cylinder 8 Glow Plug Circuit Fault

What does this mean?

What are the Possible Causes of the DTC P0678 2017 Chevrolet Silverado?

Faulty cylinder #8 glow plug
Cylinder #8 glow plug harness is open or shorted
Cylinder #8 glow plug circuit poor electrical connection
Faulty Glow Plug Control Module (GPCM)

How to Fix the DTC P0678 2017 Chevrolet Silverado?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0678 2017 Chevrolet Silverado code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

Need more information about the P0678 2017 Chevrolet Silverado code?

Need more information on how to fix the P0678 2017 Chevrolet Silverado code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P0678 2017 Chevrolet Silverado code diagnosed by a professional: Find a repair shop in your area

About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P0678 2017 Chevrolet Silverado Code

1. What are the common symptoms of OBDII code P0678 in a 2017 Chevrolet Silverado related to the Cylinder 8 Glow Plug Circuit Fault?

- Common symptoms include rough idling, difficulty starting the engine, decreased fuel efficiency, and potential misfires.

2. What are the possible causes of OBDII code P0678 in a 2017 Chevrolet Silverado indicating a Cylinder 8 Glow Plug Circuit Fault?

- The code may be triggered by a faulty glow plug, damaged wiring in the glow plug circuit, a defective glow plug control module, or issues with the vehicle's ECM.

3. How can I diagnose the Cylinder 8 Glow Plug Circuit Fault in a 2017 Chevrolet Silverado with OBDII code P0678?

- Use a multimeter to test the glow plug resistance, inspect the wiring for any visible damage, check the glow plug control module for proper functionality, and scan the vehicle for additional trouble codes.

4. Can I continue to drive my 2017 Chevrolet Silverado with OBDII code P0678 pointing to a Cylinder 8 Glow Plug Circuit Fault?

- It is not recommended to drive the vehicle extensively with this fault as it can lead to further engine issues and potential damage. It's best to address the problem promptly.

5. What are the repair options for fixing OBDII code P0678 in a 2017 Chevrolet Silverado associated with a Cylinder 8 Glow Plug Circuit Fault?

- Repair options include replacing the faulty glow plug, repairing damaged wiring, replacing the glow plug control module if needed, or resetting the ECM after fixing the issue.

6. Is it possible to reset the OBDII code P0678 in a 2017 Chevrolet Silverado after repairing the Cylinder 8 Glow Plug Circuit Fault?

- Yes, once the underlying issue causing the fault code has been resolved, you can use an OBDII scanner to clear the code and reset the vehicle's ECM.

7. How critical is it to address OBDII code P0678 related to a Cylinder 8 Glow Plug Circuit Fault in a 2017 Chevrolet Silverado promptly?

- It's important to address the issue promptly to avoid potential engine performance problems, reduced fuel efficiency, and prevent further damage to the vehicle.

8. Are there any preventive maintenance steps I can take to avoid encountering OBDII code P0678 in my 2017 Chevrolet Silverado?

- Regularly inspecting and testing the glow plugs, monitoring the glow plug circuit for any issues, and following the manufacturer's recommended maintenance schedule can help prevent this fault.

9. Can a DIY enthusiast with basic automotive skills repair OBDII code P0678 in a 2017 Chevrolet Silverado related to a Cylinder 8 Glow Plug Circuit Fault?

- Depending on the exact cause of the fault, some repairs like replacing a glow plug or checking wiring connections can be done by someone with basic automotive skills. However, complex issues may require professional help.

10. What are the potential risks of ignoring OBDII code P0678 in a 2017 Chevrolet Silverado signaling a Cylinder 8 Glow Plug Circuit Fault?

- Ignoring the fault code can lead to poor engine performance, reduced fuel efficiency, potential engine misfires, and in severe cases, damage to the engine components.