AutoCodes – Buick – B3948 Buick

B3948 Buick Code - Left Front Turn Signal Circuit

Quick Answer

Ground is applied at all times to the turn signal/multifunction switch. Common causes include Faulty Left Front Turn Signal Lamp, Left Front Turn Signal Lamp harness is open or shorted, Left 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: B3948 Buick indicates Left Front Turn Signal Circuit.
Common causes: Common causes include Faulty Left Front Turn Signal Lamp, Left Front Turn Signal Lamp harness is open or shorted, Left 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 746

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 B3948 Buick 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 B3948 Buick - Left Front Turn Signal Circuit - AutoCodes.com — B3948 Buick Code - Left Front Turn Signal Circuit

What does this mean?

What are the Possible Causes of the DTC B3948 Buick?

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

How to Fix the DTC B3948 Buick?

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 B3948 Buick 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.

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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 B3948 Buick Code

1. What are the common symptoms of OBDII code B3948 in a Buick related to the left front turn signal circuit?

- Common symptoms include the left front turn signal not working, rapid flashing of the turn signal, or a completely non-functional turn signal.

2. What are some possible causes of OBDII code B3948 in a Buick indicating a problem with the left front turn signal circuit?

- Possible causes may include a faulty turn signal bulb, a damaged wiring harness, a defective turn signal switch, or a malfunctioning body control module.

3. How can I diagnose the issue related to OBDII code B3948 affecting the left front turn signal circuit in my Buick?

- To diagnose the issue, inspect the left front turn signal bulb for damage, check the wiring harness for any breaks or corrosion, test the turn signal switch for proper functionality, and scan the body control module for error codes.

4. Is it safe to drive my Buick with OBDII code B3948 indicating a problem with the left front turn signal circuit?

- It is not recommended to drive your vehicle with non-functional turn signals, as it can pose a safety risk to you and other drivers on the road. It's best to address the issue promptly.

5. What are some repair tips for resolving OBDII code B3948 in a Buick related to the left front turn signal circuit?

- Start by checking and replacing the left front turn signal bulb if necessary. Inspect the wiring for any damage and repair or replace as needed. If the issue persists, consult a professional mechanic for further diagnosis and repair.

6. Can a DIY enthusiast fix OBDII code B3948 in a Buick affecting the left front turn signal circuit?

- Depending on your skill level and experience with automotive repairs, you may be able to address simple issues like bulb replacement or basic wiring repairs. However, complex electrical problems may require professional assistance.

7. How much does it typically cost to repair OBDII code B3948 in a Buick linked to the left front turn signal circuit?

- The cost of repair can vary based on the specific cause of the issue. Simple fixes like bulb replacement may cost less than $50, while more complex repairs involving the wiring or control module could range from $100 to $500 or more.

8. Are there any recalls or technical service bulletins related to OBDII code B3948 in Buick vehicles concerning the left front turn signal circuit?

- It's recommended to check with your local Buick dealership or visit the National Highway Traffic Safety Administration (NHTSA) website to see if there are any relevant recalls or bulletins related to this specific OBDII code.

9. Can moisture or water damage cause OBDII code B3948 to trigger in a Buick's left front turn signal circuit?

- Yes, moisture or water intrusion can lead to corrosion in the wiring or connections of the left front turn signal circuit, potentially triggering OBDII code B3948. It's important to inspect for and address any water-related issues promptly.

10. How can I prevent future occurrences of OBDII code B3948 in my Buick related to the left front turn signal circuit?

- To prevent future issues, regularly inspect and maintain your vehicle's turn signal system, including checking for proper bulb operation, securing wiring connections, and addressing any signs of moisture or water damage promptly.