P066F GMC Code - Cylinder 3 Glow Plug Control Circuit High Voltage
Quick Answer
n the diesel engine, air alone is compressed in the cylinder. Common causes include Faulty cylinder #3 glow plug, Cylinder #3 glow plug harness is open or shorted, Cylinder #3 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
- P066F GMC indicates Cylinder 3 Glow Plug Control Circuit High Voltage.
- Common causes
- Common causes include Faulty cylinder #3 glow plug, Cylinder #3 glow plug harness is open or shorted, Cylinder #3 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 P066F 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 P066F GMC?
- Faulty cylinder #3 glow plug
- Cylinder #3 glow plug harness is open or shorted
- Cylinder #3 glow plug circuit poor electrical connection
- Faulty Glow Plug Control Module
How to Fix the DTC P066F 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 P066F 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 P066F GMC code?
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Information for Specific GMC Models
- P066F 2014 GMC Sierra — Cylinder 3 Glow Plug Control Circuit High Voltage
- P066F 2015 GMC Sierra — Cylinder 3 Glow Plug Control Circuit High Voltage
- P066F 2016 GMC Sierra — Cylinder 3 Glow Plug Control Circuit High Voltage
- P066F 2017 GMC Sierra — Cylinder 3 Glow Plug Control Circuit High Voltage
- P066F 2018 GMC Sierra — Cylinder 3 Glow Plug Control Circuit High Voltage
Frequently Asked Questions about P066F GMC Code
1. What does the OBDII code P066F mean for a GMC vehicle?
P066F indicates a high voltage issue in the glow plug control circuit for cylinder 3, which is part of the diesel engine's starting system.
2. What are the common symptoms of code P066F in a GMC?
Symptoms may include difficulty starting the engine in cold weather, poor engine performance, an illuminated check engine light, or increased emissions.
3. What causes the P066F code to trigger?
Common causes include a faulty glow plug, damaged wiring or connectors in the glow plug circuit, a malfunctioning glow plug control module, or corrosion in the electrical connections.
4. Can I continue driving with a P066F code on my GMC?
While driving may still be possible, prolonged operation with this code could lead to starting issues, especially in cold weather, and should be addressed promptly to avoid further damage.
5. How do I diagnose the P066F code on a GMC?
Diagnosis involves inspecting the glow plug, checking the wiring and connectors for damage or corrosion, and testing the glow plug control module with a multimeter for proper operation.
6. How do I fix the P066F code on my GMC?
Repairs may involve replacing the faulty glow plug, repairing or replacing damaged wiring, cleaning corroded connectors, or replacing the glow plug control module if necessary.
7. How much does it cost to repair a P066F code on a GMC?
Repair costs vary but typically range from $100 to $300, depending on whether a glow plug, wiring repair, or control module replacement is needed.
8. Can a bad battery cause the P066F code on a GMC?
While a weak or failing battery may not directly cause this code, it can contribute to electrical issues that impact the glow plug system.
9. What tools do I need to troubleshoot the P066F code?
You’ll need an OBDII scanner, a digital multimeter, and basic hand tools to inspect and test the glow plug circuit components.
10. Is the P066F code specific to GMC, or does it apply to other vehicles?
The P066F code is not GMC-specific and can appear on other diesel vehicles with similar glow plug systems, but troubleshooting steps may vary by manufacturer.
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