AutoCodes – GMC – B2740 2016 GMC Sierra

B2740 2016 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 2016 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.

Save to My Repairs My Repairs

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

Code Popularity 181

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
Add Comment

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

Code B2740 2016 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 2016 GMC Sierra - Front Fog Lamp Switch Circuit Malfunction - AutoCodes.com — B2740 2016 GMC Sierra Code - Front Fog Lamp Switch Circuit Malfunction

What does this mean?

What are the Possible Causes of the DTC B2740 2016 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 2016 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 2016 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 2016 GMC Sierra code?

Need more information on how to fix the B2740 2016 GMC Sierra code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the B2740 2016 GMC Sierra 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 B2740 2016 GMC Sierra Code

1. What are the common symptoms of OBDII code B2740 in a 2016 GMC Sierra related to the front fog lamp switch circuit malfunction?

- The common symptoms include non-functioning front fog lights, the inability to turn on or off the fog lights, or an illuminated fog lamp warning light on the dashboard.

2. What are the possible causes of the front fog lamp switch circuit malfunction code B2740 in a 2016 GMC Sierra?

- Potential causes may include a faulty fog lamp switch, a damaged wiring harness or connector, a blown fuse, or a problem with the fog lamp relay.

3. How can I diagnose the front fog lamp switch circuit malfunction in my 2016 GMC Sierra triggering OBDII code B2740?

- Diagnose the issue by visually inspecting the fog lamp switch, checking the wiring for any visible damage, testing the fog lamp relay, and using a multimeter to check for continuity.

4. Can I continue driving my 2016 GMC Sierra with the OBDII code B2740 indicating a front fog lamp switch circuit malfunction?

- It is generally safe to drive the vehicle with this code, but the front fog lights may not function properly, affecting visibility in certain driving conditions.

5. How do I repair the front fog lamp switch circuit malfunction code B2740 on my 2016 GMC Sierra?

- Repair steps may involve replacing the fog lamp switch, repairing or replacing damaged wiring, checking and replacing the fog lamp relay if necessary, and resetting the trouble code.

6. Are there any specific precautions I should take while attempting to fix the front fog lamp switch circuit malfunction in my 2016 GMC Sierra?

- Ensure to disconnect the vehicle's battery before starting any repair work to prevent electrical accidents or damage to the vehicle's electrical system.

7. Will resetting the OBDII code B2740 in my 2016 GMC Sierra resolve the front fog lamp switch circuit malfunction issue?

- Resetting the code may temporarily turn off the warning light, but it will not fix the underlying problem causing the front fog lamp switch circuit malfunction.

8. How can I prevent the front fog lamp switch circuit malfunction code B2740 from occurring in my 2016 GMC Sierra in the future?

- Regularly inspect and maintain the fog lamp switch, wiring, and related components to ensure they are in good working condition and address any issues promptly.

9. Is it possible to bypass or disable the front fog lamp switch circuit in my 2016 GMC Sierra if I don't use the fog lights?

- While it may be possible to bypass the circuit, it is not recommended as it can lead to other electrical issues and may affect the vehicle's overall lighting system.

10. Can a professional mechanic help me diagnose and repair the front fog lamp switch circuit malfunction in my 2016 GMC Sierra if I'm unsure how to proceed?

- Yes, seeking assistance from a qualified mechanic or technician is recommended if you are not confident in diagnosing or repairing the issue yourself to ensure the problem is properly resolved.