P0677 2014 GMC Sierra Code - Cylinder 7 Glow Plug Circuit Fault
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
- P0677 2014 GMC Sierra indicates Cylinder 7 Glow Plug Circuit Fault.
- 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 P0677 2014 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 P0677 2014 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 (GPCM)
How to Fix the DTC P0677 2014 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 P0677 2014 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 P0677 2014 GMC Sierra Code
What does OBDII code P0677 mean for a 2014 GMC Sierra?
Code P0677 indicates a fault in the glow plug circuit for cylinder 7, meaning the glow plug may not be functioning properly.
What are the symptoms of code P0677 in a 2014 GMC Sierra?
Symptoms may include difficulty starting the engine, rough idling in cold weather, and an illuminated check engine light.
What causes code P0677 in a 2014 GMC Sierra?
Common causes include a faulty glow plug, damaged wiring or connectors in the glow plug circuit, or a malfunctioning glow plug control module.
Can driving with code P0677 damage my engine?
While driving with this code is usually safe, prolonged cold starts can cause additional stress on the engine, potentially leading to long-term damage.
How do I diagnose code P0677 on a 2014 GMC Sierra?
Diagnosis involves inspecting the glow plug, wiring, and connectors for damage, testing the resistance of the glow plug, and checking the functionality of the glow plug control module.
How do I fix code P0677 on a 2014 GMC Sierra?
Repairs may include replacing the faulty glow plug, repairing or replacing damaged wiring or connectors, or replacing a malfunctioning glow plug control module.
Can I clear code P0677 without fixing the problem?
Clearing the code without addressing the underlying issue will likely result in the code returning and continued symptoms.
How much does it cost to fix code P0677 on a 2014 GMC Sierra?
The cost varies depending on the cause, but replacing a single glow plug typically costs between $50 and $150, while more complex repairs may be higher.
What tools do I need to repair code P0677 on a 2014 GMC Sierra?
Common tools include a multimeter for testing electrical resistance, basic hand tools for removing the glow plug, and an OBDII scanner to clear the code.
Can cold weather worsen code P0677 symptoms?
Yes, cold temperatures increase reliance on glow plugs for starting, so the symptoms of this code can become more severe in colder climates.
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