AutoCodes – GMC – C0379 2017 GMC Sierra

C0379 2017 GMC Sierra Code - Front Axle Switch Circuit

Quick Answer

The front axle control circuit consists of an electric motor actuator that engages and disengages the front axle. Common causes include Faulty Front Axle Engagement Actuator, Front Axle Engagement Actuator harness is open or shorted, Front Axle Engagement Actuator 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: C0379 2017 GMC Sierra indicates Front Axle Switch Circuit.
Common causes: Common causes include Faulty Front Axle Engagement Actuator, Front Axle Engagement Actuator harness is open or shorted, Front Axle Engagement Actuator 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.

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Code Popularity 196

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Jul 11, 2023

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code C0379 2017 GMC Sierra Description

The front axle control circuit consists of an electric motor actuator that engages and disengages the front axle. The front axle engagement actuator consists of a permanent magnetic motor, a worm gear-controlled plunger, a front axle switch, and an electronic control circuit within the actuator assembly.
The front axle engagement actuator contains the following circuits: A Run/Crank Ignition 1 Voltage circuit, a Four-Wheel Drive Wheel Lock Indicator circuit, a Front Axle Actuator Control circuit, and a ground circuit.
When a shift to 4WD Auto, 4WD High, or 4WD Low is requested, the Transfer Case Control Module engages the front axle by grounding the front axle actuator control circuit through a current limiting driver.
This Diagnostic Trouble Code (DTC) will be set when a short to ground, short to voltage, or open circuit is detected.

OBDII Code C0379 2017 GMC Sierra - Front Axle Switch Circuit - AutoCodes.com — C0379 2017 GMC Sierra Code - Front Axle Switch Circuit

What does this mean?

What are the Possible Causes of the DTC C0379 2017 GMC Sierra?

Faulty Front Axle Engagement Actuator
Front Axle Engagement Actuator harness is open or shorted
Front Axle Engagement Actuator circuit poor electrical connection
Faulty Transfer Case Control Module

How to Fix the DTC C0379 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 C0379 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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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 2017 GMC Sierra Code

1. What does the OBDII code C0379 mean on a 2017 GMC Sierra?

C0379 indicates an issue with the front axle switch circuit, which is responsible for controlling the engagement of the front axle in 4WD systems.

2. What are the common symptoms of code C0379 in a 2017 GMC Sierra?

Symptoms may include the 4WD system not engaging properly, a service 4WD warning light, or unusual noises from the front axle.

3. What causes code C0379 to appear in a 2017 GMC Sierra?

The code can be triggered by a faulty front axle actuator, a damaged switch, wiring issues such as shorts or open circuits, or a malfunctioning transfer case control module (TCCM).

4. How can I diagnose code C0379 on my 2017 GMC Sierra?

Start by checking the front axle switch and actuator for proper operation. Inspect the wiring and connectors for damage, and use a scan tool to verify TCCM functionality.

5. Can a faulty front axle actuator cause code C0379?

Yes, a malfunctioning front axle actuator is a common cause of this code, as it prevents the proper engagement of the front axle.

6. Is it safe to drive with code C0379 on a 2017 GMC Sierra?

While the vehicle may still be drivable in 2WD, the 4WD system may not function correctly, which could be problematic in off-road or slippery conditions.

7. How do I fix code C0379 on a 2017 GMC Sierra?

Repair steps may include replacing a defective front axle actuator, repairing damaged wiring, or replacing the front axle switch. Always clear the code after repairs to confirm the fix.

8. Can a blown fuse cause code C0379 in a 2017 GMC Sierra?

Yes, a blown fuse in the 4WD system circuit can disrupt power to the front axle actuator or switch, triggering this code.

9. How much does it cost to repair code C0379 on a 2017 GMC Sierra?

Repair costs can vary depending on the cause, typically ranging from $100 for a simple wiring repair to $300-$500 for actuator or switch replacement.

10. Can a scan tool help resolve code C0379 on a 2017 GMC Sierra?

Yes, a scan tool can help pinpoint the issue by retrieving freeze frame data, testing the actuator and switch, and confirming communication with the TCCM.