AutoCodes – GMC – B2477 GMC

B2477 GMC Code - Reverse Light Relay Shorted To Ground

Quick Answer

When the 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: B2477 GMC indicates Reverse Light Relay Shorted To Ground.
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.

Save to My Repairs My Repairs

AI answers can be wrong. Verify repairs with testing. Open full chat

Code Popularity 748

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
Add Comment

💬 Need more help? Ask Coddy for instant answers — it's free!

Code B2477 GMC Description

When the 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 the voltage. The Diagnostic Trouble Code (DTC) B2477 will set when the voltage is approximately equal to the ground. DTC B2477 will clear when the voltage is greater than the ground for at least one monitoring cycle.

OBDII Code B2477 GMC - Reverse Light Relay Shorted To Ground - AutoCodes.com — B2477 GMC Code - Reverse Light Relay Shorted To Ground

What does this mean?

What are the Possible Causes of the DTC B2477 GMC?

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 B2477 GMC?

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 B2477 GMC 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 B2477 GMC code?

Need more information on how to fix the B2477 GMC code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the B2477 GMC code diagnosed by a professional: Find a repair shop in your area

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 B2477 GMC Code

What does the OBDII code B2477 mean for a GMC vehicle?

B2477 indicates a problem with the reverse light relay, specifically that it is shorted to ground, meaning there is an electrical fault causing the relay to continuously complete the circuit.

What symptoms might indicate a B2477 code is present?

Common symptoms include reverse lights that stay on continuously, reverse lights that do not work at all, and potential issues with the vehicle's backup camera or other reverse-related systems.

What are the possible causes of the B2477 code?

Possible causes include a defective reverse light relay, damaged wiring or connectors, a short circuit in the reverse light circuit, or issues with the vehicle's body control module (BCM).

How can I diagnose the B2477 code effectively?

Start by visually inspecting the reverse light relay, wiring, and connectors for any damage or corrosion. Use a multimeter to check for continuity and shorts in the wiring, and test the relay function.

What is the best way to repair a B2477 code?

Repair may involve replacing the faulty reverse light relay, repairing any damaged wiring or connectors, and ensuring all connections are secure. If the BCM is suspected to be faulty, it may need to be tested or replaced.

Can driving with a B2477 code cause further damage to my vehicle?

While it may not cause immediate severe damage, ignoring the issue could lead to more electrical problems or drain the battery if the reverse lights stay on continuously.

Will clearing the B2477 code fix the issue?

Clearing the code may temporarily turn off the check engine light, but it wonâ€™t resolve the underlying issue. Proper diagnosis and repair are necessary to prevent the code from reappearing.

Is it safe to drive my GMC with a B2477 code?

It is generally safe to drive, but be cautious of the reverse lights malfunctioning, which could pose a risk to other drivers when backing up. It's best to address the issue as soon as possible.

How much does it typically cost to fix a B2477 code?

Repair costs can vary widely based on the specific issue; simple relay replacements may be inexpensive, while wiring repairs or BCM replacements could be more costly, ranging from $50 to several hundred dollars.

Can I fix a B2477 code myself?

If you have experience with automotive electrical systems, you may be able to diagnose and repair the issue yourself. However, if you are unsure, it is advisable to consult a professional mechanic.