AutoCodes – Pontiac – B3948 Pontiac

B3948 Pontiac 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 Pontiac 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 1,332

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

What does this mean?

What are the Possible Causes of the DTC B3948 Pontiac?

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 Pontiac?

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 Pontiac 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 Pontiac Code

1. What are the common symptoms of OBDII code B3948 Pontiac related to the Left Front Turn Signal Circuit?

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

2. What are the possible causes of OBDII code B3948 Pontiac indicating an issue with the Left Front Turn Signal Circuit?

- The code may be triggered by a faulty turn signal bulb, a damaged wiring harness, a malfunctioning turn signal switch, or a problem with the body control module.

3. How can I diagnose the cause of OBDII code B3948 Pontiac for the Left Front Turn Signal Circuit?

- Start by visually inspecting the left front turn signal bulb and wiring for any visible damage. Use a multimeter to test the continuity of the wiring and check for any loose connections.

4. Can a blown fuse cause OBDII code B3948 Pontiac to appear for the Left Front Turn Signal Circuit?

- Yes, a blown fuse in the turn signal circuit can trigger this code. Check the fuse box for any blown fuses and replace them if necessary.

5. What are some repair tips for addressing OBDII code B3948 Pontiac related to the Left Front Turn Signal Circuit?

- Begin by replacing the left front turn signal bulb with a new one. If the issue persists, inspect the wiring harness for damage and repair or replace any faulty wires.

6. Is it possible to reset OBDII code B3948 Pontiac for the Left Front Turn Signal Circuit without making any repairs?

- Clearing the code without addressing the underlying issue will likely result in the code reappearing. It's essential to diagnose and repair the problem causing the code.

7. Can a faulty turn signal switch trigger OBDII code B3948 Pontiac for the Left Front Turn Signal Circuit?

- Yes, a malfunctioning turn signal switch can cause this code to appear. Consider replacing the turn signal switch if other components check out fine.

8. How crucial is it to address OBDII code B3948 Pontiac for the Left Front Turn Signal Circuit promptly?

- It's important to address this code promptly as it affects the proper functioning of the left front turn signal, compromising safety and indicating a potential issue with the vehicle's electrical system.

9. Are there any common related codes that may accompany OBDII code B3948 Pontiac for the Left Front Turn Signal Circuit?

- Depending on the root cause, additional codes related to turn signal malfunctions or electrical circuit failures may also be present and should be investigated.

10. Can moisture or water damage cause OBDII code B3948 Pontiac to trigger for the Left Front Turn Signal Circuit?

- Yes, moisture or water ingress into the turn signal assembly or wiring can lead to corrosion and electrical issues, potentially triggering this OBDII code.