AutoCodes – GMC – B257A 2016 GMC Sierra

B257A 2016 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 2016 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 259

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 2016 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 2016 GMC Sierra - Headlamp Switch Input Signals Correlation Malfunction - AutoCodes.com — B257A 2016 GMC Sierra Code - Headlamp Switch Input Signals Correlation Malfunction

What does this mean?

What are the Possible Causes of the DTC B257A 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 B257A 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 B257A 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 B257A 2016 GMC Sierra code?

Need more information on how to fix the B257A 2016 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 2016 GMC Sierra Code

1. What are the common symptoms of OBDII code B257A in a 2016 GMC Sierra?

The common symptoms of code B257A include issues with the headlamp switch operation, such as the lights not turning on or flickering intermittently.

2. What does the OBDII code B257A, "Headlamp Switch Input Signals Correlation Malfunction," indicate in a 2016 GMC Sierra?

This code indicates a problem with the correlation between the input signals from the headlamp switch in the vehicle's electrical system.

3. What are the possible causes of the B257A trouble code in a 2016 GMC Sierra?

Possible causes of code B257A include a faulty headlamp switch, wiring issues, a malfunctioning control module, or a poor connection in the headlamp circuit.

4. How can I diagnose the cause of the B257A trouble code in my 2016 GMC Sierra?

Diagnosing the B257A code typically involves checking the headlamp switch, inspecting the wiring for damage, testing the control module, and verifying the connections in the headlamp circuit.

5. Can I still drive my 2016 GMC Sierra with the B257A trouble code?

It is not recommended to drive your vehicle with the B257A code present, as it can affect the proper functioning of the headlamp system, compromising visibility and safety.

6. How serious is the B257A trouble code in a 2016 GMC Sierra?

While the code itself may not cause immediate drivability issues, it is important to address it promptly to ensure the proper operation of the headlamp system for safe driving.

7. How can I repair the B257A trouble code in my 2016 GMC Sierra?

Repairing the B257A code may involve replacing the headlamp switch, repairing damaged wiring, addressing control module issues, or fixing poor connections in the headlamp circuit.

8. Can I reset the B257A trouble code in my 2016 GMC Sierra without making repairs?

Resetting the code without addressing the underlying issue is not recommended, as the problem will likely recur, and it is crucial to fix the root cause to prevent further issues.

9. Will the B257A trouble code in my 2016 GMC Sierra cause other problems if left unattended?

If left unattended, the B257A code may lead to further electrical issues in the headlamp system, potentially affecting other components and causing more significant problems over time.

10. How much does it typically cost to fix the B257A trouble code in a 2016 GMC Sierra?

The cost of fixing the B257A code can vary depending on the specific cause of the issue, but it may involve parts and labor expenses for replacing components or repairing the electrical system.