AutoCodes – GMC – B256B 2014 GMC Sierra

B256B 2014 GMC Sierra Code - Cargo Lamps Switch Circuit Malfunction

Quick Answer

The cargo lamp relay is always supplied with battery voltage. Common causes include Faulty Cargo Lamps Switch, Cargo Lamps Switch harness is open or shorted, Cargo Lamps 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: B256B 2014 GMC Sierra indicates Cargo Lamps Switch Circuit Malfunction.
Common causes: Common causes include Faulty Cargo Lamps Switch, Cargo Lamps Switch harness is open or shorted, Cargo Lamps 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 191

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 B256B 2014 GMC Sierra Description

The cargo lamp relay is always supplied with battery voltage. The cargo lamp switch signal circuit is grounded momentarily by pressing the cargo lamp switch. The Body Control Module (BCM) energizes the cargo lamp relay by applying ground to the cargo lamp relay control circuit. When the cargo lamp relay is energized, the relay switch contacts close, and battery voltage is applied through the F9DR fuse to the cargo lamp control circuit which illuminates the cargo lamps. The Diagnostic Trouble Code (DTC) will be set when the BCM detects a short to ground in the cargo lamp switch signal circuit.

OBDII Code B256B 2014 GMC Sierra - Cargo Lamps Switch Circuit Malfunction - AutoCodes.com — B256B 2014 GMC Sierra Code - Cargo Lamps Switch Circuit Malfunction

What does this mean?

What are the Possible Causes of the DTC B256B 2014 GMC Sierra?

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

How to Fix the DTC B256B 2014 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 B256B 2014 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 B256B 2014 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 B256B 2014 GMC Sierra Code

1. What does the OBDII code B256B mean on a 2014 GMC Sierra?

B256B indicates a malfunction in the cargo lamp switch circuit, meaning thereâ€™s an issue with the electrical system controlling the cargo lamp.

2. What are the common symptoms of code B256B in a 2014 GMC Sierra?

Symptoms may include the cargo lamp not turning on or off, the cargo lamp staying on indefinitely, or a dashboard warning related to the exterior lighting system.

3. What causes the B256B code to appear on a 2014 GMC Sierra?

Common causes include a faulty cargo lamp switch, damaged wiring, corroded electrical connections, or a malfunctioning Body Control Module (BCM).

4. How can I diagnose the B256B code in a 2014 GMC Sierra?

Start by inspecting the cargo lamp switch and wiring for damage or corrosion. Use a multimeter to test for proper voltage and continuity in the circuit. A scan tool can also help verify if the BCM is functioning correctly.

5. Can I still drive my 2014 GMC Sierra with a B256B code?

Yes, the vehicle is still drivable, but the cargo lamp may not function properly, which could be inconvenient, especially in low-light conditions.

6. How do I fix the B256B code on a 2014 GMC Sierra?

Repairs may include replacing the malfunctioning cargo lamp switch, repairing damaged wiring, cleaning corroded connectors, or reprogramming/replacing the BCM if necessary.

7. How much does it cost to repair a B256B code on a 2014 GMC Sierra?

Repair costs vary but typically range from $50 to $200, depending on whether the issue is with the switch, wiring, or BCM.

8. Can a blown fuse cause the B256B code on a 2014 GMC Sierra?

While less common, a blown fuse in the cargo lamp circuit could contribute to the code. Check all related fuses before proceeding with more complex diagnostics.

9. Will clearing the B256B code fix the problem in my 2014 GMC Sierra?

Clearing the code may temporarily remove the warning, but the underlying issue must be addressed to prevent the code from returning.

10. Do I need special tools to fix the B256B code on a 2014 GMC Sierra?

Basic tools like a multimeter and a scan tool are helpful for diagnosing and repairing this issue. Advanced diagnostics may require specialized equipment for the BCM.