P068C GMC 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 GMC 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 GMC 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 GMC?
- 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 GMC?
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 GMC 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 P068C GMC code?
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Need Help with the Code?
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Information for Specific GMC Models
- P068C 2014 GMC Sierra — Cylinder 7 Glow Plug Control Circuit Low Voltage
- P068C 2015 GMC Sierra — Cylinder 7 Glow Plug Control Circuit Low Voltage
- P068C 2016 GMC Sierra — Cylinder 7 Glow Plug Control Circuit Low Voltage
- P068C 2017 GMC Sierra — Cylinder 7 Glow Plug Control Circuit Low Voltage
- P068C 2018 GMC Sierra — Cylinder 7 Glow Plug Control Circuit Low Voltage
Frequently Asked Questions about P068C GMC Code
What does the OBDII code P068C mean for GMC vehicles?
The P068C code on GMC vehicles refers to a low voltage issue in the cylinder 7 glow plug control circuit, indicating a problem with the glow plug system.
What are the symptoms of code P068C in GMC vehicles?
Common symptoms include difficulty starting the engine in cold weather, rough idling, decreased fuel efficiency, and the illumination of the check engine light.
What causes the P068C code to appear on GMC vehicles?
This code can be caused by a faulty glow plug, damaged wiring or connectors, a defective glow plug control module, or issues with the vehicle's electrical system, such as low battery voltage.
Can I drive my GMC vehicle with code P068C active?
It’s possible to drive with this code active, but prolonged operation can lead to starting issues in cold weather and potentially damage the glow plug system further.
How is the P068C code diagnosed?
A mechanic will typically use an OBDII scanner to confirm the code, inspect the glow plug control circuit, check wiring for damage, and test the glow plug and control module for proper function.
What repairs are commonly needed for code P068C?
Repairs may include replacing the cylinder 7 glow plug, fixing damaged wiring or connectors, or replacing the glow plug control module.
How much does it cost to fix code P068C on a GMC vehicle?
The cost depends on the specific repair needed. Replacing a glow plug typically costs $100-$200, while replacing the glow plug control module can range from $300-$500.
Can a weak battery trigger the P068C code?
Yes, a weak or failing battery can cause low voltage issues in the glow plug control circuit, potentially triggering the P068C code.
How can I prevent the P068C code from occurring?
Regular maintenance, including checking the glow plug system, ensuring the battery is in good condition, and inspecting wiring for damage, can help prevent this code.
What happens if the P068C code is ignored?
Ignoring the P068C code can lead to starting difficulties, particularly in cold weather, and may result in further damage to the glow plug system or related components.
Discuss the causes and fixes for P068C GMC OBDII Code
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