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AutoCodes – GMC – B2545 2018 GMC Sierra

B2545 2018 GMC Sierra Code - Backup Lamps Circuit

Quick Answer

The backup lamp relay is always supplied with battery voltage. Common causes include Blown Backup Lamp Fuse, Faulty Body Control Module (BCM), Body Control Module harness is open or shorted. 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
B2545 2018 GMC Sierra indicates Backup Lamps Circuit.
Common causes
Common causes include Blown Backup Lamp Fuse, Faulty Body Control Module (BCM), Body Control Module harness is open or shorted.
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 231
How popular is this code, among other codes? Low
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Table of contents Created and updated by William Orellana on May 24, 2023
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Code B2545 2018 GMC Sierra Description

The backup lamp relay is always supplied with battery voltage. With the engine running and the transmission in the reverse position, the Transmission Control Module (TCM) sends a serial data message to the Body Control Module (BCM). The message indicates that the gear selector is in the reverse position. The BCM energizes the backup lamp relay by applying battery voltage to the backup lamp relay control circuit. When the backup lamp relay is energized, the relay switch contacts close, and battery voltage is applied through the backup lamp fuses to the backup lamp control circuits which illuminate the backup lamps. Once the driver moves the gear selector out of the reverse position, a message is sent by the TCM via serial data requesting the BCM to remove the battery voltage from the backup lamp relay control circuit. The engine must be running for the backup lamps to operate. The Diagnostic Trouble Code (DTC) will be set when the BCM detects a problem with the backup lamps relay control circuit.
OBDII Code B2545 2018 GMC Sierra - Backup Lamps Circuit - AutoCodes.com
B2545 2018 GMC Sierra Code - Backup Lamps Circuit
What does this mean?

What are the Possible Causes of the DTC B2545 2018 GMC Sierra?

  • Blown Backup Lamp Fuse
  • Faulty Body Control Module (BCM)
  • Body Control Module harness is open or shorted
  • Body Control Module circuit poor electrical connection

How to Fix the DTC B2545 2018 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 does this mean?

Code Tech Notes

B2545:01 Backup Lamps Circuit Short to Battery
B2545:02 Backup Lamps Circuit Short to Ground
B2545:02 Backup Lamps Circuit Open

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the B2545 2018 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 B2545 2018 GMC Sierra code?

Need more information on how to fix the B2545 2018 GMC Sierra code? Get Access to Factory Service Manuals

Need Help with the 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 B2545 2018 GMC Sierra Code

1. What does the OBDII code B2545 mean on a 2018 GMC Sierra?

B2545 indicates an issue with the Backup Lamps Circuit, typically suggesting a fault in the wiring, bulb, or control module.

2. What are the common symptoms of code B2545 in a 2018 GMC Sierra?

Symptoms include non-functional backup lights, a dashboard warning light, or inconsistent illumination when in reverse.

3. What causes the B2545 code to appear?

Common causes include a faulty backup lamp bulb, damaged wiring, corroded connectors, or a malfunctioning Body Control Module (BCM).

4. Can a blown fuse trigger the B2545 code?

Yes, a blown fuse in the backup light circuit can cause the code to appear and prevent the lamps from working.

5. How do you diagnose the B2545 code?

Start by checking the backup light bulbs, inspecting the wiring and connectors for damage or corrosion, and testing the fuse and BCM functionality.

6. Can I drive my 2018 GMC Sierra with the B2545 code active?

Yes, but it’s unsafe, as non-functional backup lamps reduce visibility when reversing, increasing the risk of an accident.

7. How do I fix the B2545 code on my GMC Sierra?

Replace any burnt-out bulbs, repair damaged wiring or connectors, check and replace the fuse if necessary, or reprogram/replace the BCM if faulty.

8. Does a bad reverse gear switch cause the B2545 code?

Yes, a faulty reverse gear switch may fail to signal the backup lights to turn on, triggering the code.

9. How much does it cost to repair a B2545 issue on a 2018 GMC Sierra?

Costs range from $20 for a bulb replacement to $300+ for BCM reprogramming or replacement, depending on the exact issue.

10. Can clearing the B2545 code solve the problem?

Clearing the code without addressing the underlying issue will not fix the problem, and the code is likely to return.

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