AutoCodes – GMC – B3949 GMC

B3949 GMC Code - Right Front Turn Signal Circuit

Quick Answer

Ground is applied at all times to the turn signal/multifunction switch. Common causes include Faulty Right Front Turn Signal Lamp, Right Front Turn Signal Lamp harness is open or shorted, Right Front Turn Signal Lamp 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: B3949 GMC indicates Right Front Turn Signal Circuit.
Common causes: Common causes include Faulty Right Front Turn Signal Lamp, Right Front Turn Signal Lamp harness is open or shorted, Right Front Turn Signal Lamp 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 1,213

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 Jun 17, 2023

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code B3949 GMC Description

Ground is applied at all times to the turn signal/multifunction switch. The turn signal lamps may only be activated with the ignition switch in the ON or START positions. When the turn signal/multifunction switch is placed in either the TURN RIGHT or TURN LEFT position, ground is applied to the Body Control Module (BCM) through either the right turn or left turn signal switch signal circuit. The BCM responds to the turn signal switch input by applying a pulsating voltage to the front and rear turn signal lamps through there respective control circuits. When a turn signal request is received by the BCM, a serial data message is sent to the instrument cluster requesting the respective turn signal indicator be pulsed ON and OFF. The Diagnostic Trouble Code (DTC) will be set when the BCM detects an open/high resistance in the left front turn signal control circuit.

OBDII Code B3949 GMC - Right Front Turn Signal Circuit - AutoCodes.com — B3949 GMC Code - Right Front Turn Signal Circuit

What does this mean?

What are the Possible Causes of the DTC B3949 GMC?

Faulty Right Front Turn Signal Lamp
Right Front Turn Signal Lamp harness is open or shorted
Right Front Turn Signal Lamp circuit poor electrical connection
Faulty Body Control Module (BCM)

How to Fix the DTC B3949 GMC?

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 B3949 GMC 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.

Need more information about the B3949 GMC code?

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Need Help with the Code?

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Information for Specific GMC Models

B3949 2014 GMC Sierra — Right Front Turn Signal Circuit
B3949 2015 GMC Sierra — Right Front Turn Signal Circuit
B3949 2016 GMC Sierra — Right Front Turn Signal Circuit
B3949 2017 GMC Sierra — Right Front Turn Signal Circuit
B3949 2018 GMC Sierra — Right Front Turn Signal Circuit

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 GMC Code

1. What are common symptoms of OBDII code B3949 GMC (Right Front Turn Signal Circuit)?

Symptoms may include the right front turn signal not working, rapid blinking of the turn signal, or a warning light on the dashboard.

2. What are possible causes of OBDII code B3949 GMC?

Potential causes include a faulty turn signal bulb, a damaged wiring harness, a defective turn signal socket, or a problem with the turn signal switch.

3. How can I diagnose the issue related to OBDII code B3949 GMC?

To diagnose the problem, you can visually inspect the right front turn signal bulb, check the wiring for any visible damage, test the turn signal socket for proper connectivity, and use a multimeter to check for voltage.

4. Can I repair OBDII code B3949 GMC on my own?

If the issue is a simple one like a burnt-out bulb, you may be able to replace it yourself. However, more complex issues with wiring or components may require professional diagnosis and repair.

5. Is it safe to drive with OBDII code B3949 GMC triggered?

Driving with a faulty right front turn signal can compromise your safety and the safety of others on the road. It's best to address the issue promptly to ensure proper signaling while driving.

6. How much does it typically cost to repair OBDII code B3949 GMC?

The cost of repair can vary depending on the underlying issue. Replacing a turn signal bulb may cost around $10-$20, while repairing wiring or components can range from $50 to a few hundred dollars.

7. Will resetting the OBDII code B3949 GMC turn off the warning light?

Resetting the code may temporarily turn off the warning light, but if the root cause of the issue is not fixed, the code is likely to reappear and the warning light will come back on.

8. Can extreme weather conditions affect OBDII code B3949 GMC?

Yes, extreme weather conditions like heavy rain or snow can potentially damage the wiring or components related to the right front turn signal, leading to the triggering of this OBDII code.

9. How long does it typically take to repair OBDII code B3949 GMC?

The repair time can vary depending on the complexity of the issue. Simple fixes like replacing a bulb can be done in a few minutes, while more intricate repairs may take an hour or more.

10. Are there any preventive measures to avoid OBDII code B3949 GMC in the future?

Regularly checking and maintaining your vehicle's turn signal bulbs, wiring, and sockets can help prevent issues like OBDII code B3949 GMC. Additionally, addressing any electrical problems promptly can help avoid more serious issues down the line.