AutoCodes – GMC – B256B 2016 GMC Sierra

B256B 2016 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 2016 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 204

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 2016 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 2016 GMC Sierra - Cargo Lamps Switch Circuit Malfunction - AutoCodes.com — B256B 2016 GMC Sierra Code - Cargo Lamps Switch Circuit Malfunction

What does this mean?

What are the Possible Causes of the DTC B256B 2016 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 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 B256B 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 B256B 2016 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 2016 GMC Sierra Code

1. What are the common symptoms of OBDII code B256B on a 2016 GMC Sierra related to Cargo Lamps Switch Circuit Malfunction?

- Common symptoms include inoperative cargo lamps, flickering or dim cargo lamps, or the cargo lamp switch not functioning properly.

2. What are the possible causes of OBDII code B256B on a 2016 GMC Sierra?

- The code B256B can be triggered by issues such as a faulty cargo lamp switch, damaged wiring or connectors in the circuit, or a malfunctioning cargo lamp control module.

3. How can I diagnose the Cargo Lamps Switch Circuit Malfunction on my 2016 GMC Sierra?

- To diagnose the issue, you can start by visually inspecting the cargo lamp switch, checking the wiring and connectors for any damage, and using a multimeter to test for continuity and proper voltage in the circuit.

4. Can a DIY enthusiast repair the Cargo Lamps Switch Circuit Malfunction associated with OBDII code B256B?

- Depending on the specific cause, DIY repairs may be possible, such as replacing a faulty cargo lamp switch or repairing damaged wiring. However, complex issues may require professional diagnosis and repair.

5. Is it safe to continue driving my 2016 GMC Sierra with OBDII code B256B indicating a Cargo Lamps Switch Circuit Malfunction?

- While the vehicle may still be drivable with this code, it is recommended to address the issue promptly to avoid potential safety hazards or further electrical problems in the vehicle.

6. How can I reset the OBDII code B256B on my 2016 GMC Sierra after repairing the Cargo Lamps Switch Circuit Malfunction?

- After repairing the issue causing the code B256B, you can reset the code using an OBDII scanner or by disconnecting the vehicle's battery for a few minutes to clear the error code.

7. Are there any common mistakes to avoid when troubleshooting OBDII code B256B on a 2016 GMC Sierra?

- One common mistake to avoid is overlooking simple causes like a loose connector or blown fuse when diagnosing the Cargo Lamps Switch Circuit Malfunction, as these can sometimes be the root of the issue.

8. What are the typical repair costs associated with fixing OBDII code B256B on a 2016 GMC Sierra?

- The repair costs can vary depending on the specific cause of the issue. Simple fixes like replacing a switch or repairing wiring may be relatively affordable, while more complex problems could incur higher repair costs.

9. Can extreme weather conditions or water exposure contribute to triggering OBDII code B256B on a 2016 GMC Sierra?

- Yes, extreme weather conditions or water exposure can potentially damage the cargo lamp circuit components, leading to a malfunction and triggering the B256B trouble code.

10. Is it recommended to seek professional help for diagnosing and repairing OBDII code B256B on a 2016 GMC Sierra?

- If you are unsure about diagnosing or repairing the Cargo Lamps Switch Circuit Malfunction, it is recommended to seek help from a qualified mechanic or an automotive technician familiar with GMC vehicles to ensure proper resolution of the issue.