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Engine-Codes – GMC – B3950 2016 GMC Sierra

B3950 2016 GMC Sierra Code - Left Rear Turn Signal Circuit

Quick Answer

The B3950 diagnostic trouble code (DTC) for a 2016 GMC Sierra relates to the left rear turn signal circuit. Common causes include Faulty left rear turn signal bulb, Corrosion or loose connections in the turn signal wiring, Defective body 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
B3950 2016 GMC Sierra indicates Left Rear Turn Signal Circuit.
Common causes
Common causes include Faulty left rear turn signal bulb, Corrosion or loose connections in the turn signal wiring, Defective body 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 17, 2024
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Code B3950 2016 GMC Sierra Description

The B3950 diagnostic trouble code (DTC) for a 2016 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. The turn signal circuit is crucial for indicating to other drivers when the vehicle is making a left turn or changing lanes to the left. When this circuit is not functioning correctly, it can pose a safety hazard as it affects the visibility of the vehicle to other drivers on the road.

OBDII Code B3950 2016 GMC Sierra - Left Rear Turn Signal Circuit
B3950 2016 GMC Sierra Code - Left Rear Turn Signal Circuit

Common Causes of B3950 2016 GMC Sierra

  1. Faulty left rear turn signal bulb
  2. Corrosion or loose connections in the turn signal wiring
  3. Defective body control module
  4. Blown fuse related to the turn signal circuit
  5. Water damage or moisture intrusion in the turn signal assembly

Symptoms of B3950 2016 GMC Sierra

  1. Left rear turn signal not working
  2. Rapid blinking of the turn signal indicator on the dashboard
  3. Dim or flickering left rear turn signal
  4. Check engine light illuminated on the dashboard

How to Fix B3950 2016 GMC Sierra

  1. Begin by visually inspecting the left rear turn signal bulb for any signs of damage or burnout. Replace the bulb if necessary.
  2. Check the wiring connections for the left rear turn signal for corrosion or looseness. Clean the connections and secure them properly.
  3. Test the body control module for any faults related to the left rear turn signal circuit. Replace the BCM if needed.
  4. Inspect the fuses related to the turn signal circuit and replace any blown fuses.
  5. Check the turn signal assembly for water damage or moisture intrusion. Seal any gaps or replace the assembly if necessary.

Cost to Fix B3950 2016 GMC Sierra

The typical repair costs for addressing the B3950 code for the left rear turn signal circuit on a 2016 GMC Sierra can range from $100 to $300, depending on the specific cause of the issue and the cost of parts and labor. It's important to note that diagnosis time and labor rates at auto repair shops can vary, so it's advisable to check with local shops for a more accurate estimate. Keep in mind that rates may be higher at dealerships or in metropolitan areas, while independent shops may offer more affordable prices.

What does this mean?

Tech Notes for B3950 2016 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 2016 GMC Sierra Code

1. What does the OBDII code B3950 mean on a 2016 GMC Sierra?

B3950 indicates an issue with the left rear turn signal circuit, such as an open or short in the wiring, a faulty bulb, or a problem with the related control module.

2. What are the symptoms of code B3950 on a 2016 GMC Sierra?

Common symptoms include the left rear turn signal not working, hyper-flashing of the turn signal indicator, or a warning message on the dashboard.

3. What causes the B3950 code to appear on a 2016 GMC Sierra?

Causes may include a burned-out turn signal bulb, damaged wiring or connectors, corrosion at the bulb socket, or a malfunctioning Body Control Module (BCM).

4. How can I troubleshoot the B3950 code on a 2016 GMC Sierra?

Start by inspecting the left rear turn signal bulb and socket for damage or corrosion. Check the wiring and connectors for continuity or signs of wear. If all physical components are fine, scan the BCM for further faults.

5. Can I drive my 2016 GMC Sierra with the B3950 code active?

It’s not recommended, as a non-functioning turn signal can create safety hazards and may lead to traffic violations.

6. How do I fix the B3950 code on a 2016 GMC Sierra?

Replace the faulty turn signal bulb if necessary. Clean or repair corroded or damaged connectors and wiring. If the issue persists, the BCM may need to be reprogrammed or replaced.

7. How much does it cost to repair the B3950 code on a 2016 GMC Sierra?

Costs vary depending on the issue. A bulb replacement is inexpensive, typically under $20, while wiring or BCM repairs could cost $100-$500 or more.

8. Can a weak battery cause the B3950 code on a 2016 GMC Sierra?

A weak or failing battery is unlikely to directly cause the B3950 code but can lead to electrical malfunctions that might trigger other related issues.

9. Do I need special tools to diagnose the B3950 code on a 2016 GMC Sierra?

A multimeter is helpful for testing continuity in the wiring, and an OBDII scanner capable of reading BCM codes is recommended for accurate diagnosis.

10. Can a faulty fuse cause the B3950 code on a 2016 GMC Sierra?

Yes, a blown fuse in the turn signal circuit may result in the B3950 code. Check the fuse box and replace any blown fuses as part of your troubleshooting.

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