AutoCodes – GMC – B257A 2015 GMC Sierra

B257A 2015 GMC Sierra Code - Headlamp Switch Input Signals Correlation Malfunction

Quick Answer

For headlamp operation, the Body Control Module (BCM) monitors three signal circuits from the headlamp switch. 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: B257A 2015 GMC Sierra indicates Headlamp Switch Input Signals Correlation 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 174

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 May 26, 2023

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code B257A 2015 GMC Sierra Description

For headlamp operation, the Body Control Module (BCM) monitors three signal circuits from the headlamp switch. When the headlamp switch is in the AUTO position, the three signal circuits are unaffected and the BCM relies on the ambient light sensor input to turn the headlamps and daytime running lamps ON and OFF. When the headlamp switch is placed in the OFF position, the headlamp switch headlamps OFF signal circuit is grounded, indicating to the BCM that the exterior lamps should be turned OFF. With the headlamp switch in the PARK LAMPS position, the headlamp switch park lamps ON signal circuit is grounded, indicating that the park lamps have been requested. When the headlamp switch is in the HEADLAMP position, both the headlamp switch park lamps ON signal circuit and the headlamp switch headlamps ON signal circuit are grounded. The BCM responds by commanding the park lamps and low beam headlamps ON.

OBDII Code B257A 2015 GMC Sierra - Headlamp Switch Input Signals Correlation Malfunction - AutoCodes.com — B257A 2015 GMC Sierra Code - Headlamp Switch Input Signals Correlation Malfunction

What does this mean?

What are the Possible Causes of the DTC B257A 2015 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 B257A 2015 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 B257A 2015 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 B257A 2015 GMC Sierra code?

Need more information on how to fix the B257A 2015 GMC Sierra code? Get Access to Factory Service Manuals

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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 B257A 2015 GMC Sierra Code

1. What are the common symptoms of OBDII code B257A on a 2015 GMC Sierra?

- Common symptoms include malfunctioning headlamp switch, erratic headlight behavior, or dashboard warning lights related to the lighting system.

2. What does the OBDII code B257A indicating "Headlamp Switch Input Signals Correlation Malfunction" mean for a 2015 GMC Sierra?

- This code indicates a discrepancy between the input signals received by the headlamp switch, leading to potential issues with the vehicle's lighting system.

3. What are the possible causes of the B257A OBDII code on a 2015 GMC Sierra?

- Possible causes include a faulty headlamp switch, wiring issues, a bad headlamp control module, or a malfunctioning body control module.

4. How can I diagnose the source of the B257A trouble code on my 2015 GMC Sierra?

- Diagnosis involves checking the headlamp switch operation, inspecting the wiring for any damage, testing the headlamp control module, and scanning the body control module for related error codes.

5. Can I still drive my 2015 GMC Sierra with the B257A trouble code present?

- It is generally safe to drive with this code, but it's essential to address the underlying issue promptly to ensure proper functioning of the lighting system.

6. How can I clear the B257A trouble code on my 2015 GMC Sierra?

- Clearing the code can be done with an OBDII scanner or by disconnecting the vehicle's battery for a few minutes to reset the system.

7. Is it possible to repair the B257A code on a 2015 GMC Sierra without professional help?

- Depending on your mechanical skills, you may be able to address this issue by replacing the headlamp switch or fixing wiring problems. However, complex diagnostics may require professional assistance.

8. Will the B257A code reset itself after repairs on a 2015 GMC Sierra?

- In some cases, the code may clear itself after the repairs are made and the vehicle goes through a few drive cycles without detecting the issue. Otherwise, manual clearing may be necessary.

9. How much does it typically cost to repair the B257A trouble code on a 2015 GMC Sierra?

- The cost of repair can vary depending on the exact cause of the issue, but it may range from a simple switch replacement to more complex wiring or module repairs, potentially costing a few hundred dollars.

10. Are there any preventive measures to avoid the B257A trouble code on a 2015 GMC Sierra?

- Regularly checking the functionality of the headlamp switch, inspecting wiring for damage, and addressing any lighting system issues promptly can help prevent the occurrence of this trouble code.