AutoCodes – Chevrolet – B3948 2018 Chevrolet Silverado

B3948 2018 Chevrolet Silverado 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 2018 Chevrolet Silverado 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.

Save to My Repairs My Repairs

AI answers can be wrong. Verify repairs with testing. Open full chat

Code Popularity 266

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
Add Comment

💬 Need more help? Ask Coddy for instant answers — it's free!

Code B3948 2018 Chevrolet Silverado 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 2018 Chevrolet Silverado - Left Front Turn Signal Circuit - AutoCodes.com — B3948 2018 Chevrolet Silverado Code - Left Front Turn Signal Circuit

What does this mean?

What are the Possible Causes of the DTC B3948 2018 Chevrolet Silverado?

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 2018 Chevrolet Silverado?

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 2018 Chevrolet Silverado 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 B3948 2018 Chevrolet Silverado code?

Need more information on how to fix the B3948 2018 Chevrolet Silverado code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the B3948 2018 Chevrolet Silverado code diagnosed by a professional: Find a repair shop in your area

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 2018 Chevrolet Silverado Code

1. What does OBDII code B3948 for a 2018 Chevrolet Silverado mean?

The code B3948 indicates a problem with the left front turn signal circuit on a 2018 Chevrolet Silverado.

2. What are common symptoms of OBDII code B3948 in a 2018 Chevrolet Silverado?

Common symptoms of code B3948 may include the left front turn signal not working, fast blinking of the turn signal, or a warning light on the dashboard.

3. What are possible causes of OBDII code B3948 in a 2018 Chevrolet Silverado?

Possible causes of code B3948 can include a faulty turn signal bulb, a damaged wiring harness, a malfunctioning turn signal switch, or a problem with the body control module.

4. How can I diagnose the issue causing OBDII code B3948 in my 2018 Chevrolet Silverado?

To diagnose the issue, you can start by checking the left front turn signal bulb, inspecting the wiring for any damage, testing the turn signal switch, and scanning the body control module for fault codes.

5. Can I repair OBDII code B3948 in my 2018 Chevrolet Silverado myself?

Depending on the cause of the code, you may be able to repair it yourself by replacing the faulty turn signal bulb, repairing any damaged wiring, or addressing the issue with the turn signal switch. More complex issues may require professional assistance.

6. Is it safe to continue driving my 2018 Chevrolet Silverado with OBDII code B3948?

It is not recommended to drive the vehicle with a malfunctioning turn signal as it can pose a safety hazard to you and other drivers on the road. It's best to address the issue promptly.

7. How much can I expect to pay to fix OBDII code B3948 in my 2018 Chevrolet Silverado?

The cost of fixing code B3948 can vary depending on the cause of the issue and whether you choose to repair it yourself or seek professional help. Costs may include parts and labor for the repairs.

8. Can a loose connection cause OBDII code B3948 in a 2018 Chevrolet Silverado?

Yes, a loose or poor connection in the left front turn signal circuit can trigger code B3948. Make sure to check all connections for secureness during diagnosis.

9. Will resetting the OBDII system clear code B3948 in my 2018 Chevrolet Silverado?

Resetting the OBDII system may temporarily clear the code, but if the underlying issue causing B3948 is not addressed, the code is likely to reappear. It's important to diagnose and fix the root cause.

10. How can I prevent OBDII code B3948 from occurring in my 2018 Chevrolet Silverado in the future?

To prevent code B3948, regularly inspect your turn signal bulbs, maintain the wiring harnesses, and address any turn signal issues promptly to avoid further complications.