P068C 2017 GMC Sierra Code - Cylinder 7 Glow Plug Control Circuit Low Voltage
Quick Answer
n the diesel engine, air alone is compressed in the cylinder. Common causes include Faulty cylinder #7 glow plug, Cylinder #7 glow plug harness is open or shorted, Cylinder #7 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
- P068C 2017 GMC Sierra indicates Cylinder 7 Glow Plug Control Circuit Low Voltage.
- Common causes
- Common causes include Faulty cylinder #7 glow plug, Cylinder #7 glow plug harness is open or shorted, Cylinder #7 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 P068C 2017 GMC Sierra 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 P068C 2017 GMC Sierra?
- Faulty cylinder #7 glow plug
- Cylinder #7 glow plug harness is open or shorted
- Cylinder #7 glow plug circuit poor electrical connection
- Faulty Glow Plug Control Module
How to Fix the DTC P068C 2017 GMC Sierra?
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 P068C 2017 GMC Sierra 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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Frequently Asked Questions about P068C 2017 GMC Sierra Code
1. What does the OBDII code P068C mean for a 2017 GMC Sierra?
P068C indicates a low voltage issue in the glow plug control circuit for cylinder 7, which can affect the engine's ability to start and perform efficiently in cold conditions.
2. What are the common symptoms of code P068C?
Symptoms may include difficulty starting the engine, rough idle, decreased fuel efficiency, and the check engine light turning on.
3. What causes the P068C code to appear?
Common causes include a faulty glow plug, damaged wiring or connectors in the glow plug control circuit, a malfunctioning glow plug control module, or battery-related issues.
4. Can driving with code P068C cause damage to my GMC Sierra?
While it might not cause immediate damage, prolonged driving with this code can lead to poor engine performance and may exacerbate cold start issues.
5. How can I diagnose the P068C code?
Use a diagnostic scanner to confirm the code, then inspect the glow plug, wiring, connectors, and control module for visible damage or wear.
6. How do I fix the P068C code on a 2017 GMC Sierra?
Repairs may involve replacing the faulty glow plug, repairing or replacing damaged wiring, cleaning connections, or replacing the glow plug control module.
7. Is code P068C specific to cold weather conditions?
Yes, the glow plug system is primarily used to assist in starting the engine during cold weather, so issues are more noticeable in colder climates.
8. How much does it cost to repair code P068C?
Repair costs vary but can range from $100 to $500, depending on whether the glow plug, wiring, or control module needs replacement.
9. Can I clear the P068C code without repairing it?
You can clear the code using a diagnostic scanner, but it will likely return unless the underlying issue is addressed.
10. How often do glow plugs need replacement in a 2017 GMC Sierra?
Glow plugs typically last 100,000 miles or more, but their lifespan can vary depending on driving conditions and maintenance practices.
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