AutoCodes – GMC – B2740 2017 GMC Sierra

B2740 2017 GMC Sierra Code - Front Fog Lamp Switch Circuit Malfunction

Quick Answer

The front fog lamp relay is supplied with battery voltage at all times. Common causes include Faulty Headlamp Switch, Headlamp Switch harness is open or shorted, Headlamp Switch 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: B2740 2017 GMC Sierra indicates Front Fog Lamp Switch Circuit Malfunction.
Common causes: Common causes include Faulty Headlamp Switch, Headlamp Switch harness is open or shorted, Headlamp Switch 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 385

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 01, 2023

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code B2740 2017 GMC Sierra Description

The front fog lamp relay is supplied with battery voltage at all times. The front fog lamp switch signal circuit is grounded momentarily by pressing the front fog lamp switch. The Body Control Module (BCM) energizes the front fog lamp relay by applying ground to the front fog lamp relay control circuit. When the front fog lamp relay is energized, the relay switch contacts close, and battery voltage is applied through the fog lamp fuse to the front fog lamp control circuit which illuminates the front fog lamps. With the front fog lamp switch activated the BCM sends a message via serial data to the instrument cluster requesting the instrument cluster to illuminate the front fog indicator. The Diagnostic Trouble Code (DTC) sets when the BCM detects a short to ground in the front fog lamp switch signal circuit.

OBDII Code B2740 2017 GMC Sierra - Front Fog Lamp Switch Circuit Malfunction - AutoCodes.com — B2740 2017 GMC Sierra Code - Front Fog Lamp Switch Circuit Malfunction

What does this mean?

What are the Possible Causes of the DTC B2740 2017 GMC Sierra?

Faulty Headlamp Switch
Headlamp Switch harness is open or shorted
Headlamp Switch circuit poor electrical connection
Faulty Body Control Module (BCM)

How to Fix the DTC B2740 2017 GMC Sierra?

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 B2740 2017 GMC Sierra 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 B2740 2017 GMC Sierra code?

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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 B2740 2017 GMC Sierra Code

1. What are the common symptoms of OBDII code B2740 in a 2017 GMC Sierra?

- Common symptoms include the front fog lamps not turning on, flickering, or staying on constantly without input from the switch.

2. What causes the Front Fog Lamp Switch Circuit Malfunction code (B2740) in a 2017 GMC Sierra?

- The code B2740 is typically triggered by issues with the front fog lamp switch, wiring issues, a faulty fog lamp control module, or a blown fuse.

3. How can I diagnose the Front Fog Lamp Switch Circuit Malfunction in my 2017 GMC Sierra?

- Start by visually inspecting the front fog lamp switch, wiring, and related components for any visible damage or loose connections. Use an OBDII scanner to retrieve the specific trouble codes.

4. Can I still drive my 2017 GMC Sierra with the B2740 code present?

- It is generally safe to drive with this code, but it is recommended to address the issue promptly to ensure proper functionality of the front fog lamps.

5. What is the typical repair process for the B2740 code in a 2017 GMC Sierra?

- The repair process usually involves checking and repairing any damaged wiring, replacing the front fog lamp switch if necessary, inspecting and possibly replacing the fog lamp control module, and ensuring the fuse is intact.

6. Are there any DIY tips for fixing the Front Fog Lamp Switch Circuit Malfunction in a 2017 GMC Sierra?

- DIY tips include checking and securing any loose connections, inspecting the fuse for continuity, and testing the front fog lamp switch for proper operation using a multimeter.

7. How much does it cost to repair the B2740 code in a 2017 GMC Sierra?

- The cost of repairs can vary depending on the specific issue causing the code. It could range from a simple fix like replacing a fuse to more complex repairs involving component replacements.

8. Can weather conditions affect the Front Fog Lamp Switch Circuit Malfunction code in a 2017 GMC Sierra?

- Extreme weather conditions like water exposure or severe temperature fluctuations can potentially cause electrical issues that may trigger the B2740 code.

9. Will resetting the OBDII codes clear the B2740 code in a 2017 GMC Sierra?

- Resetting the OBDII codes may temporarily clear the code, but if the underlying issue is not fixed, the B2740 code is likely to reappear after driving the vehicle.

10. How do I prevent the Front Fog Lamp Switch Circuit Malfunction code from recurring in my 2017 GMC Sierra?

- Regularly inspect and maintain the front fog lamp system, including checking the wiring, switches, and control module for any signs of wear or damage. Address any issues promptly to prevent the code from recurring.