AutoCodes – Buick – B2478 Buick

B2478 Buick Code - Reverse Light Relay Shorted To Battery

Quick Answer

When Platform Zone Module (PZM) receives input that transaxle is in Reverse, PZM energizes reverse light relay which will turn on back-up lights. Common causes include Faulty Reverse Light Relay, Reverse Light Relay harness is open or shorted, Reverse Light Relay 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: B2478 Buick indicates Reverse Light Relay Shorted To Battery.
Common causes: Common causes include Faulty Reverse Light Relay, Reverse Light Relay harness is open or shorted, Reverse Light Relay 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 542

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 Dec 09, 2019

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code B2478 Buick Description

When Platform Zone Module (PZM) receives input that transaxle is in Reverse, PZM energizes reverse light relay which will turn on back-up lights. When back-up lights have been commanded on, PZM constantly measures voltage. The Diagnostic Trouble Code (DTC) B2478 will set when voltage is not at ground potential for at least 2 seconds. DTC B2478 will clear when voltage is greater than the ground for at least one monitoring cycle.

OBDII Code B2478 Buick - Reverse Light Relay Shorted To Battery - AutoCodes.com — B2478 Buick Code - Reverse Light Relay Shorted To Battery

What does this mean?

What are the Possible Causes of the DTC B2478 Buick?

Faulty Reverse Light Relay
Reverse Light Relay harness is open or shorted
Reverse Light Relay circuit poor electrical connection
Faulty Platform Zone Module (PZM)

How to Fix the DTC B2478 Buick?

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 B2478 Buick 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 B2478 Buick 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 B2478 Buick Code

1. What are the common symptoms of OBDII code B2478 in a Buick related to the reverse light relay being shorted to battery?

- The common symptoms include reverse lights staying on constantly even when the vehicle is not in reverse gear.

2. What are the potential causes of the OBDII code B2478 indicating a reverse light relay shorted to battery in a Buick?

- The common causes are a faulty reverse light relay, damaged wiring, or a short circuit in the reverse light circuit.

3. How can I diagnose the issue with the reverse light relay causing the OBDII code B2478 in my Buick?

- You can use a multimeter to test the continuity of the wiring, check the reverse light relay for proper functioning, and visually inspect the wiring for any signs of damage.

4. What steps can I take to repair the reverse light relay shorted to battery issue indicated by the OBDII code B2478 in my Buick?

- Repairing the issue involves replacing the faulty reverse light relay, repairing the damaged wiring, and fixing any short circuits present in the reverse light circuit.

5. Is it safe to continue driving my Buick with the OBDII code B2478 related to a reverse light relay shorted to battery?

- It is not recommended to drive the vehicle with this issue as it can cause safety concerns and drain the battery due to the reverse lights staying on constantly.

6. Can I reset the OBDII code B2478 in my Buick related to the reverse light relay without fixing the issue?

- While you can reset the code using an OBDII scanner, it is essential to address the underlying problem to prevent the code from reappearing.

7. How can I prevent the reverse light relay from shorting to the battery in my Buick in the future?

- Regularly inspecting the reverse light circuit, ensuring proper installation of the relay, and avoiding any water damage to the wiring can help prevent this issue.

8. Are there any safety implications associated with the reverse light relay being shorted to battery in a Buick?

- Yes, driving with the reverse lights constantly on can confuse other drivers and lead to accidents, making it important to address the issue promptly.

9. Can a DIY enthusiast repair the reverse light relay shorted to battery problem indicated by the OBDII code B2478 in a Buick?

- If you have experience with automotive electrical systems and proper tools, you can attempt to repair the issue yourself. However, seeking professional help is recommended if you are unsure.

10. How long does it typically take to repair the reverse light relay shorted to battery issue causing the OBDII code B2478 in a Buick?

- The repair time can vary depending on the extent of the damage and your experience level. It may take anywhere from 1-3 hours to complete the repair successfully.