AutoCodes – Generic – B256B

B256B 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 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 311

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

What does this mean?

What are the Possible Causes of the DTC B256B?

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?

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 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 code?

Need more information on how to fix the B256B code? Get Access to Factory Service Manuals

Need Help with the Code?

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Information for Specific Makes

B256B Buick — Cargo Lamps Switch Circuit Malfunction
B256B Cadillac — Cargo Lamps Switch Circuit Malfunction
B256B Chevrolet — Cargo Lamps Switch Circuit Malfunction
B256B GMC — Cargo Lamps Switch Circuit Malfunction

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 Code

1. What are the common symptoms of OBDII code B256B (Cargo Lamps Switch Circuit Malfunction)?

- The common symptoms include inoperative cargo lamps, flickering cargo lamps, or a warning light on the dashboard.

2. What are the possible causes of OBDII code B256B?

- Possible causes of this code include a faulty cargo lamp switch, damaged wiring or connectors in the circuit, or a malfunctioning control module.

3. How can I diagnose the issue causing OBDII code B256B?

- You can diagnose the issue by visually inspecting the cargo lamp switch and its wiring, testing the switch for continuity, and using a diagnostic scanner to check for stored codes.

4. Can a loose or corroded connection cause OBDII code B256B?

- Yes, a loose or corroded connection in the cargo lamp switch circuit can result in code B256B being triggered.

5. Is it safe to continue driving with OBDII code B256B active?

- It is generally safe to drive with this code, but it is recommended to address the issue promptly to ensure the cargo lamps function properly.

6. How can I repair OBDII code B256B myself?

- You can repair the code by replacing a faulty cargo lamp switch, repairing damaged wiring or connectors, or resetting the control module after addressing the issue.

7. Will resetting the OBDII code B256B turn off the warning light?

- Resetting the code may turn off the warning light temporarily, but if the underlying issue is not fixed, the code and light may reappear.

8. Can extreme weather conditions cause OBDII code B256B to trigger?

- Extreme weather conditions such as moisture or extreme temperatures can sometimes lead to circuit malfunctions that trigger code B256B.

9. How much does it typically cost to repair OBDII code B256B at a mechanic?

- The cost of repairs for code B256B can vary depending on the specific issue, but it may range from $100 to $300 at a mechanic's shop.

10. Is it possible for OBDII code B256B to be a false alarm?

- While rare, it is possible for code B256B to be triggered falsely due to a temporary glitch in the system. It is recommended to clear the code and monitor if it reoccurs.