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Engine-Codes – GMC – C0379 2018 GMC Sierra

C0379 2018 GMC Sierra Code - Front Axle Switch Circuit

Quick Answer

The C0379 diagnostic trouble code (DTC) for a 2018 GMC Sierra relates to the Front Axle Switch Circuit. Common causes include Faulty front axle switch, Damaged wiring or connectors in the circuit, Malfunctioning control module. 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
C0379 2018 GMC Sierra indicates Front Axle Switch Circuit.
Common causes
Common causes include Faulty front axle switch, Damaged wiring or connectors in the circuit, Malfunctioning control module.
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.
What is this?
Table of contents Created and updated by William Orellana on Sep 13, 2024
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Code C0379 2018 GMC Sierra Description

The C0379 diagnostic trouble code (DTC) for a 2018 GMC Sierra relates to the Front Axle Switch Circuit. This code indicates that there is a malfunction in the circuit that controls the front axle engagement system. In vehicles equipped with four-wheel drive, the front axle switch is responsible for engaging or disengaging the front axle to switch between two-wheel drive and four-wheel drive modes. When this circuit malfunctions, it can lead to issues with engaging the front axle, which can affect the vehicle's drivability and performance.

OBDII Code C0379 2018 GMC Sierra - Front Axle Switch Circuit
C0379 2018 GMC Sierra Code - Front Axle Switch Circuit

Common Causes of C0379 2018 GMC Sierra

  1. Faulty front axle switch
  2. Damaged wiring or connectors in the circuit
  3. Malfunctioning control module
  4. Corrosion or moisture in the circuit components
  5. Electrical issues such as short circuits or open circuits

Symptoms of C0379 2018 GMC Sierra

  1. Difficulty engaging or disengaging four-wheel drive mode
  2. Illumination of the four-wheel drive warning light on the dashboard
  3. Unusual noises coming from the front axle area
  4. Decreased traction and stability in slippery or off-road conditions

How to Fix C0379 2018 GMC Sierra

  1. Diagnose the issue by using a scan tool to retrieve the DTC and perform a visual inspection of the front axle switch circuit components.
  2. Test the front axle switch for proper functionality and inspect the wiring harness for any damage or corrosion.
  3. Replace the front axle switch if it is found to be faulty and repair any damaged wiring or connectors.
  4. Clear the DTC from the vehicle's computer system and test the four-wheel drive system to ensure proper engagement and disengagement.
  5. If the issue persists, further diagnostic testing may be required to identify any underlying problems with the control module or other components.

Cost to Fix C0379 2018 GMC Sierra

The typical repair costs for addressing a Front Axle Switch Circuit issue can vary depending on the extent of the problem and the specific components that need to be replaced. In general, replacing a faulty front axle switch and repairing damaged wiring or connectors can range from $200 to $500, including parts and labor. However, additional costs may apply if the control module needs to be replaced or if further diagnostic testing is necessary.

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about C0379 2018 GMC Sierra Code

1. What are common symptoms of OBDII code C0379 Front Axle Switch Circuit in a 2018 GMC Sierra?

The common symptoms include the inability to engage or disengage the front axle, illuminated service 4WD light on the dashboard, and a loss of functionality in the 4WD system.

2. What are the potential causes of OBDII code C0379 in a 2018 GMC Sierra?

Possible causes of this code include a faulty front axle switch, damaged wiring or connectors in the circuit, a malfunctioning transfer case control module, or issues with the front axle actuator.

3. How can I diagnose the OBDII code C0379 Front Axle Switch Circuit issue in my 2018 GMC Sierra?

Diagnosing this issue typically involves using a scan tool to retrieve the trouble codes, inspecting the front axle switch and related wiring for damage, testing the front axle actuator, and checking the transfer case control module for proper operation.

4. Can I still drive my 2018 GMC Sierra with OBDII code C0379 Front Axle Switch Circuit?

It is generally not recommended to drive the vehicle with this code present, as it can lead to potential safety issues and further damage to the 4WD system. It's best to address the problem promptly.

5. How can I repair OBDII code C0379 in my 2018 GMC Sierra?

Repairing this code may involve replacing the front axle switch, repairing or replacing damaged wiring or connectors, testing and potentially replacing the front axle actuator, or reprogramming the transfer case control module.

6. Are there any DIY tips for fixing OBDII code C0379 in a 2018 GMC Sierra?

While some basic troubleshooting steps can be done by DIY enthusiasts, diagnosing and repairing this code may require specialized tools and expertise. It's recommended to consult a professional mechanic for accurate diagnosis and repair.

7. How much does it typically cost to repair OBDII code C0379 Front Axle Switch Circuit in a 2018 GMC Sierra?

The cost of repairing this code can vary depending on the exact cause of the issue, the required parts, and labor costs. It's advisable to get a few quotes from different repair shops to compare prices.

8. Can a faulty front axle switch cause other issues in a 2018 GMC Sierra besides triggering OBDII code C0379?

Yes, a faulty front axle switch can potentially cause other issues such as difficulty engaging or disengaging 4WD, erratic 4WD system behavior, or even complete failure of the 4WD system.

9. Is OBDII code C0379 Front Axle Switch Circuit a common problem in 2018 GMC Sierra vehicles?

While not extremely common, issues with the front axle switch circuit can occur in 2018 GMC Sierra vehicles, particularly in those subjected to harsh driving conditions or off-road use.

10. How can I prevent OBDII code C0379 Front Axle Switch Circuit from occurring in my 2018 GMC Sierra?

Regular maintenance, avoiding harsh driving conditions, and promptly addressing any issues with the 4WD system can help prevent the occurrence of this OBDII code in your 2018 GMC Sierra.

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