P0678 Chevrolet 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 Chevrolet 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.
Code P0678 Chevrolet Description
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.
What are the Possible Causes of the DTC P0678 Chevrolet?
- 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 Chevrolet?
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 Chevrolet 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.
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Information for Specific Chevrolet Models
- P0678 2014 Chevrolet Silverado — Cylinder 8 Glow Plug Circuit Fault
- P0678 2015 Chevrolet Silverado — Cylinder 8 Glow Plug Circuit Fault
- P0678 2016 Chevrolet Silverado — Cylinder 8 Glow Plug Circuit Fault
- P0678 2017 Chevrolet Silverado — Cylinder 8 Glow Plug Circuit Fault
- P0678 2018 Chevrolet Silverado — Cylinder 8 Glow Plug Circuit Fault
Frequently Asked Questions about P0678 Chevrolet Code
1. What are the common symptoms of OBDII code P0678 in a Chevrolet related to the cylinder 8 glow plug circuit fault?
- Common symptoms include hard starting, rough idling, misfires, reduced engine power, and the illumination of the check engine light.
2. What are the possible causes of the cylinder 8 glow plug circuit fault (P0678) in a Chevrolet?
- Potential causes may include a faulty glow plug in cylinder 8, damaged wiring or connectors in the glow plug circuit, or a malfunctioning glow plug control module.
3. How can I diagnose the cylinder 8 glow plug circuit fault in my Chevrolet triggering code P0678?
- Diagnosis typically involves checking the resistance of the glow plug, inspecting the wiring and connectors for damage, and testing the glow plug control module for proper operation.
4. Can I drive my Chevrolet with OBDII code P0678 related to the cylinder 8 glow plug circuit fault?
- It is not recommended to drive the vehicle with this fault, as it can lead to performance issues and potential damage to the engine over time. It is advisable to address the issue promptly.
5. Are there any safety concerns associated with OBDII code P0678 in a Chevrolet due to the cylinder 8 glow plug circuit fault?
- While not a direct safety risk, driving with this fault can impact the vehicle's performance and fuel efficiency, potentially leaving you stranded if the issue worsens.
6. How much does it typically cost to repair the cylinder 8 glow plug circuit fault triggering OBDII code P0678 in a Chevrolet?
- The cost of repair can vary depending on the exact cause of the fault, but it may range from $100 to $300 for parts and labor.
7. Can I replace the glow plug in cylinder 8 myself to address OBDII code P0678 in my Chevrolet?
- If you have the necessary tools and mechanical skills, replacing the glow plug in cylinder 8 can be done as a DIY repair. However, it is important to follow proper procedures to avoid causing additional damage.
8. Will resetting the check engine light clear OBDII code P0678 related to the cylinder 8 glow plug circuit fault in my Chevrolet?
- Resetting the check engine light will clear the code temporarily, but if the underlying issue is not addressed, the code is likely to reappear once the vehicle is driven and the system performs its self-diagnostic checks.
9. Is it possible for a loose connection to cause OBDII code P0678 related to the cylinder 8 glow plug circuit fault in a Chevrolet?
- Yes, a loose or poor connection in the glow plug circuit can lead to the fault code P0678. It is important to check for and secure any loose connections during diagnosis and repair.
10. How long does it typically take to repair the cylinder 8 glow plug circuit fault causing OBDII code P0678 in a Chevrolet?
- The repair time can vary based on the exact cause of the fault and the technician's experience. In general, the repair may take anywhere from 1 to 3 hours to complete.
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