Engine-CodesGMC – B3950 2014 GMC Sierra

B3950 2014 GMC Sierra Code - Left Rear Turn Signal Circuit

Quick Answer

The B3950 diagnostic trouble code (DTC) for a 2014 GMC Sierra relates to the left rear turn signal circuit. Common causes include Faulty left rear turn signal bulb, Damaged wiring harness leading to the left rear turn signal, Malfunctioning 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
B3950 2014 GMC Sierra indicates Left Rear Turn Signal Circuit.
Common causes
Common causes include Faulty left rear turn signal bulb, Damaged wiring harness leading to the left rear turn signal, Malfunctioning 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.
Table of contents Created and updated by William Orellana on Sep 15, 2024
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Code B3950 2014 GMC Sierra Description

The B3950 diagnostic trouble code (DTC) for a 2014 GMC Sierra relates to the left rear turn signal circuit. This code indicates that there is a malfunction in the electrical circuit responsible for controlling the left rear turn signal on the vehicle. The turn signal circuit is a crucial component of the vehicle's lighting system, as it is responsible for indicating to other drivers on the road when the vehicle is turning left. When this circuit is not functioning properly, it can pose a safety hazard as other drivers may not be aware of the vehicle's intentions on the road.

OBDII Code B3950 2014 GMC Sierra - Left Rear Turn Signal Circuit
B3950 2014 GMC Sierra Code - Left Rear Turn Signal Circuit

Common Causes of B3950 2014 GMC Sierra

  1. Faulty left rear turn signal bulb
  2. Damaged wiring harness leading to the left rear turn signal
  3. Malfunctioning turn signal switch
  4. Blown fuse related to the left rear turn signal circuit
  5. Issues with the vehicle's electrical system

Symptoms of B3950 2014 GMC Sierra

  1. Left rear turn signal not working
  2. Rapid blinking of left rear turn signal
  3. Dashboard indicator for left turn signal flashing rapidly
  4. Turn signal indicator on the vehicle's instrument panel staying on constantly

How to Fix B3950 2014 GMC Sierra

  1. Begin by visually inspecting the left rear turn signal bulb to check for any signs of damage or burnout. Replace the bulb if necessary.
  2. Inspect the wiring harness connected to the left rear turn signal for any frayed or damaged wires. Repair or replace any damaged wiring.
  3. Test the turn signal switch to ensure it is functioning correctly. Replace the switch if it is found to be faulty.
  4. Check the fuses related to the left rear turn signal circuit and replace any blown fuses.
  5. If the issue persists, perform a thorough diagnostic of the vehicle's electrical system to identify any underlying problems causing the left rear turn signal circuit malfunction.

Cost to Fix B3950 2014 GMC Sierra

The typical repair costs for addressing the B3950 code on a 2014 GMC Sierra can vary depending on the specific cause of the issue. In general, the cost of replacing a turn signal bulb ranges from $5 to $20, while repairing or replacing a wiring harness can cost between $50 and $200. A turn signal switch replacement can range from $50 to $150, and replacing fuses may cost around $5 to $20. Labor costs at auto repair shops typically range from $80 to $150 per hour, but rates can vary based on location and the shop's pricing structure. It is recommended to consult with a professional mechanic for a more accurate cost estimate based on the specific diagnosis of the issue.

Tech Notes for B3950 2014 GMC Sierra

B3950:01 Left Rear Turn Signal Circuit Short to Battery

B3950:02 Left Rear Turn Signal Circuit Short to Ground

B3950:04 Left Rear Turn Signal Circuit Open

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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 B3950 2014 GMC Sierra Code

1. What does the OBDII code B3950 mean on a 2014 GMC Sierra?

The B3950 code indicates a malfunction in the left rear turn signal circuit, often caused by wiring, bulb, or control module issues.

2. What are the symptoms of the B3950 code on a GMC Sierra?

Symptoms include the left rear turn signal not working, rapid turn signal flashing, or the turn signal indicator staying illuminated.

3. What causes the B3950 code to appear?

Common causes include a burned-out left rear turn signal bulb, damaged wiring, a faulty connector, or a malfunctioning body control module (BCM).

4. Can a bad bulb trigger the B3950 code?

Yes, a defective or burned-out left rear turn signal bulb can cause this code to appear.

5. How do you diagnose the B3950 code on a 2014 GMC Sierra?

Start by inspecting the left rear turn signal bulb, socket, and wiring for damage, then check the connectors and test the circuit for continuity.

6. Is the B3950 code serious?

While not critical, the code affects your turn signal functionality, which is important for safe driving and legal compliance.

7. How do you fix the B3950 code on a GMC Sierra?

Repairs may involve replacing the bulb, repairing damaged wiring, cleaning corroded connectors, or reprogramming/replacing the BCM if necessary.

8. Can a bad Body Control Module (BCM) cause the B3950 code?

Yes, a malfunctioning BCM can fail to properly control the turn signal circuit, triggering this code.

9. Why is my turn signal blinking fast with the B3950 code?

Rapid flashing indicates a fault in the turn signal circuit, often due to a burned-out bulb or a wiring issue.

10. How much does it cost to fix the B3950 code?

Costs vary depending on the issue but typically range from $20 for a bulb replacement to $400 or more if the BCM needs replacement.

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