AutoCodes – Saturn – B3948 Saturn

B3948 Saturn 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 Saturn 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 607

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

What does this mean?

What are the Possible Causes of the DTC B3948 Saturn?

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 Saturn?

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 Saturn 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 Saturn Code

1. What are the common symptoms of OBDII code B3948 Saturn (Left Front Turn Signal Circuit)?

The common symptoms include the left front turn signal not working or flashing erratically, fast blinking of the turn signal indicator on the dashboard, or a warning light on the instrument cluster.

2. What are the possible causes of OBDII code B3948 Saturn (Left Front Turn Signal Circuit)?

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

3. How can I diagnose the issue related to OBDII code B3948 Saturn (Left Front Turn Signal Circuit)?

You can start by visually inspecting the left front turn signal bulb and the wiring harness for any visible damage. Using a multimeter, test the continuity of the wiring and check for power at the bulb socket when the turn signal is activated.

4. Can I repair OBDII code B3948 Saturn (Left Front Turn Signal Circuit) myself?

Depending on your level of automotive experience, you may be able to repair the issue yourself by replacing the faulty turn signal bulb, repairing damaged wiring, or replacing a defective turn signal switch. However, more complex issues may require professional diagnosis and repair.

5. How important is it to address OBDII code B3948 Saturn (Left Front Turn Signal Circuit)?

It is essential to address this issue promptly as a malfunctioning turn signal can compromise your safety on the road and may result in a traffic violation. Additionally, other motorists may not be able to anticipate your intended maneuvers if your turn signal is not functioning correctly.

6. Can OBDII code B3948 Saturn (Left Front Turn Signal Circuit) cause other electrical problems in the vehicle?

While the code specifically relates to the left front turn signal circuit, electrical issues in one part of the vehicle can sometimes lead to issues in other systems. It's important to address the root cause of the problem to prevent further electrical issues.

7. Is it necessary to reset the OBDII system after repairing OBDII code B3948 Saturn (Left Front Turn Signal Circuit)?

Once the issue has been diagnosed and repaired, it is recommended to reset the OBDII system to clear the fault code and ensure that the repair was successful. This can be done using an OBDII scanner or by disconnecting the vehicle's battery for a few minutes.

8. Can extreme weather conditions affect OBDII code B3948 Saturn (Left Front Turn Signal Circuit)?

Extreme weather conditions, such as heavy rain or snow, can potentially exacerbate electrical issues in the turn signal circuit. Moisture intrusion or corrosion in the wiring harness can lead to malfunctions. It's important to keep the vehicle well maintained to prevent weather-related problems.

9. How long does it typically take to repair OBDII code B3948 Saturn (Left Front Turn Signal Circuit)?

The repair time can vary depending on the root cause of the issue. Simple fixes like replacing a turn signal bulb may only take a few minutes, while diagnosing and repairing a wiring harness issue could take longer. It's best to consult a professional if you're unsure about the repair process.

10. Will OBDII code B3948 Saturn (Left Front Turn Signal Circuit) cause my vehicle to fail an emissions test?

While the left front turn signal circuit issue may not directly affect emissions, it is still important to address for safety reasons. However, if the malfunctioning turn signal is part of a broader electrical problem that impacts emissions-related components, it could potentially cause the vehicle to fail an emissions test.