Engine-CodesGMC – B3950 2017 GMC Sierra

B3950 2017 GMC Sierra Code - Left Rear Turn Signal Circuit

Quick Answer

The B3950 diagnostic trouble code (DTC) for a 2017 GMC Sierra relates to the left rear turn signal circuit. Common causes include Faulty left rear turn signal bulb, Damaged wiring or connectors in the turn signal circuit, 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 2017 GMC Sierra indicates Left Rear Turn Signal Circuit.
Common causes
Common causes include Faulty left rear turn signal bulb, Damaged wiring or connectors in the turn signal circuit, 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 13, 2024
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Code B3950 2017 GMC Sierra Description

The B3950 diagnostic trouble code (DTC) for a 2017 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 an essential component of the vehicle's lighting system, which is crucial for signaling intentions to other drivers on the road. When this circuit is compromised, it can affect the safety of the vehicle and its occupants.

OBDII Code B3950 2017 GMC Sierra - Left Rear Turn Signal Circuit
B3950 2017 GMC Sierra Code - Left Rear Turn Signal Circuit

Common Causes of B3950 2017 GMC Sierra

  1. Faulty left rear turn signal bulb
  2. Damaged wiring or connectors in the turn signal circuit
  3. Malfunctioning turn signal switch
  4. Issue with the body control module
  5. Corrosion or poor connections in the electrical system

Symptoms of B3950 2017 GMC Sierra

  1. Left rear turn signal not illuminating or flashing
  2. Rapid blinking of the turn signal indicator on the dashboard
  3. Turn signal indicator staying on continuously
  4. Turn signal not turning off after completing a turn
  5. Error message on the instrument cluster related to the turn signal circuit

How to Fix B3950 2017 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 and connectors in the left rear turn signal circuit for any visible damage or corrosion. Repair or replace any damaged components.
  3. Test the turn signal switch to ensure it is functioning correctly. Replace the switch if it is found to be faulty.
  4. Use a diagnostic tool to scan the vehicle's body control module for any error codes related to the turn signal circuit. Address any identified issues.
  5. Clear the DTC from the vehicle's onboard computer and test the left rear turn signal to ensure it is operating properly.

Cost to Fix B3950 2017 GMC Sierra

The typical repair costs for addressing the B3950 code on a 2017 GMC Sierra can vary depending on the specific cause of the issue. In general, the cost of replacing a turn signal bulb can range from $5 to $20, while repairing wiring or connectors may cost between $50 and $200. If the turn signal switch or body control module needs to be replaced, the cost can increase significantly, potentially ranging from $200 to $500 or more. Additionally, labor costs for diagnosis and repair can vary between $80 and $150 per hour. It is advisable to consult with a professional mechanic or auto repair shop for a more accurate estimate based on the specific circumstances of the vehicle.

Tech Notes for B3950 2017 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 2017 GMC Sierra Code

1. What are the common symptoms of OBDII code B3950 on a 2017 GMC Sierra related to the Left Rear Turn Signal Circuit?

The common symptoms include the left rear turn signal not functioning properly, such as blinking too quickly or not working at all.

2. What are the possible causes of OBDII code B3950 on a 2017 GMC Sierra Left Rear Turn Signal Circuit?

Potential causes include a burnt-out bulb, a faulty turn signal relay, a broken wiring connection, or a malfunctioning turn signal switch.

3. How can I diagnose the issue related to OBDII code B3950 on my 2017 GMC Sierra's Left Rear Turn Signal Circuit?

You can start by visually inspecting the left rear turn signal bulb, checking the fuse, examining the wiring for any damage, and testing the turn signal relay and switch.

4. Can I continue driving my 2017 GMC Sierra with OBDII code B3950 related to the Left Rear Turn Signal Circuit?

It is not recommended to drive with a malfunctioning turn signal as it poses a safety hazard. Get the issue diagnosed and repaired promptly.

5. How can I repair OBDII code B3950 on a 2017 GMC Sierra Left Rear Turn Signal Circuit?

Repair steps may include replacing the left rear turn signal bulb, repairing damaged wiring, replacing the turn signal relay or switch, or resetting the fault code after fixing the issue.

6. Is it possible for a loose connection to cause OBDII code B3950 on a 2017 GMC Sierra Left Rear Turn Signal Circuit?

Yes, a loose or corroded connection in the left rear turn signal circuit can cause the code to trigger. Ensure all connections are secure and free of corrosion.

7. Can extreme weather conditions affect the triggering of OBDII code B3950 on a 2017 GMC Sierra Left Rear Turn Signal Circuit?

Yes, extreme weather conditions like heavy rain or snow can impact the operation of the turn signal circuit, leading to issues triggering the OBDII code.

8. Will resetting the OBDII system clear OBDII code B3950 related to the Left Rear Turn Signal Circuit on a 2017 GMC Sierra?

Resetting the OBDII system may temporarily clear the code, but if the underlying issue is not fixed, the code is likely to reappear. It's essential to diagnose and repair the problem.

9. How can I prevent OBDII code B3950 from recurring on my 2017 GMC Sierra Left Rear Turn Signal Circuit after repair?

Regularly inspect and maintain the turn signal system, including checking bulbs, ensuring proper connections, and addressing any issues promptly to prevent the code from reoccurring.

10. Are there any specific tools or equipment recommended for diagnosing and repairing OBDII code B3950 on a 2017 GMC Sierra Left Rear Turn Signal Circuit?

Basic tools like a multimeter, electrical tape, replacement bulbs, and a wiring diagram for your vehicle can be helpful for diagnosing and repairing issues related to the Left Rear Turn Signal Circuit.

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