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Engine-Codes – GMC – B3949 2018 GMC Sierra

B3949 2018 GMC Sierra Code - Right Front Turn Signal Circuit

Quick Answer

The B3949 diagnostic trouble code (DTC) for a 2018 GMC Sierra relates to the right front turn signal circuit. Common causes include Faulty wiring or connectors in the right front turn signal circuit, Burned-out or damaged right front turn signal bulb, Defective turn signal switch. 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
B3949 2018 GMC Sierra indicates Right Front Turn Signal Circuit.
Common causes
Common causes include Faulty wiring or connectors in the right front turn signal circuit, Burned-out or damaged right front turn signal bulb, Defective turn signal switch.
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 19, 2024
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Code B3949 2018 GMC Sierra Description

The B3949 diagnostic trouble code (DTC) for a 2018 GMC Sierra relates to the right front turn signal circuit. This code indicates that there is a malfunction in the electrical circuit responsible for controlling the right front turn signal on the vehicle. The turn signal circuit is crucial for indicating the driver's intention to turn or change lanes, ensuring safe navigation on the road. When this circuit is compromised, it can lead to a variety of issues affecting the vehicle's safety and functionality.

OBDII Code B3949 2018 GMC Sierra - Right Front Turn Signal Circuit
B3949 2018 GMC Sierra Code - Right Front Turn Signal Circuit

Common Causes of B3949 2018 GMC Sierra

  1. Faulty wiring or connectors in the right front turn signal circuit
  2. Burned-out or damaged right front turn signal bulb
  3. Defective turn signal switch
  4. Malfunctioning turn signal relay
  5. Issue with the body control module

Symptoms of B3949 2018 GMC Sierra

  1. Right front turn signal not illuminating
  2. Rapid blinking of the right front turn signal
  3. Dim or flickering right front turn signal
  4. Dashboard indicator for right turn signal flashing rapidly
  5. Turn signal not automatically turning off after completing a turn

How to Fix B3949 2018 GMC Sierra

  1. Begin by visually inspecting the right front turn signal bulb and socket for any signs of damage or corrosion. Replace the bulb if necessary.
  2. Check the wiring and connectors in the right front turn signal circuit for any breaks or loose connections. Repair or replace damaged components.
  3. Test the turn signal switch and relay for proper functionality. Replace any faulty components.
  4. If the issue persists, perform a diagnostic scan to identify any codes related to the body control module. Address any underlying issues with the module.
  5. Clear the DTC and test the right front turn signal to ensure proper operation.

Cost to Fix B3949 2018 GMC Sierra

The cost of repairing the right front turn signal circuit can vary depending on the specific cause of the issue and the extent of the repairs needed. In general, replacing a turn signal bulb can cost between $10 and $30, while addressing wiring or connector issues may range from $50 to $200. If the problem is related to the turn signal switch, relay, or body control module, the cost can increase significantly, potentially ranging from $100 to $500 or more. Labor costs at auto repair shops typically range from $80 to $150 per hour, so the total repair bill can vary based on the shop's rates and the time required to diagnose and fix the issue. It's advisable to consult with a trusted mechanic or dealership for a more accurate cost estimate based on the specific circumstances of the vehicle.

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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 B3949 2018 GMC Sierra Code

1. What are the common symptoms of OBDII code B3949 on a 2018 GMC Sierra related to the Right Front Turn Signal Circuit?

The common symptoms include the right front turn signal not functioning properly or flickering intermittently.

2. What are the possible causes of OBDII code B3949 on a 2018 GMC Sierra?

Possible causes include a faulty right front turn signal bulb, a damaged wiring harness, a defective turn signal switch, or a problem with the body control module.

3. How can I troubleshoot OBDII code B3949 on my 2018 GMC Sierra?

You can start by checking the condition of the right front turn signal bulb, inspecting the wiring for any visible damage, and testing the turn signal switch for proper functionality.

4. Can a DIY enthusiast repair OBDII code B3949 on a 2018 GMC Sierra?

Yes, depending on the cause of the code, a DIY enthusiast with the necessary tools and skills can replace a faulty bulb, repair a damaged wire, or replace a defective turn signal switch.

5. Is it important to address OBDII code B3949 promptly on a 2018 GMC Sierra?

Yes, it is important to address the code promptly to ensure proper operation of the right front turn signal for safety reasons and to prevent potential issues with the vehicle's electrical system.

6. What are the potential risks of ignoring OBDII code B3949 on a 2018 GMC Sierra?

Ignoring the code could lead to safety hazards on the road, such as reduced visibility when making right turns, which may increase the risk of accidents.

7. How much does it typically cost to repair OBDII code B3949 on a 2018 GMC Sierra at a professional auto repair shop?

The cost of repairing the code can vary depending on the cause and the labor rates of the repair shop, but it may range from $50 to $200 or more.

8. Can OBDII code B3949 on a 2018 GMC Sierra be cleared with a diagnostic scanner after the issue is resolved?

Yes, once the underlying issue causing the code is fixed, it can be cleared using a diagnostic scanner to reset the vehicle's computer system.

9. Are there any recalls or technical service bulletins related to OBDII code B3949 on a 2018 GMC Sierra?

It is recommended to check with a GMC dealership or visit the National Highway Traffic Safety Administration (NHTSA) website to see if there are any relevant recalls or bulletins related to this code.

10. How often does OBDII code B3949 related to the Right Front Turn Signal Circuit occur in a 2018 GMC Sierra?

The occurrence of this specific code can vary depending on factors such as vehicle usage, maintenance, and driving conditions, but it is not considered a common issue.

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