AutoCodes – GMC – B3979 2015 GMC Sierra

B3979 2015 GMC Sierra Code - Incorrect Environmental Identifier Received from HVAC Control Module

Quick Answer

When certain modules are programmed and configured during installation, the module learns a specific environment identifier which is unique to the vehicle. Common causes include Faulty Heating, Ventilation, and Air Conditioning (HVAC) Control Module, HVAC Control Module harness is open or shorted, HVAC Control Module 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: B3979 2015 GMC Sierra indicates Incorrect Environmental Identifier Received from HVAC Control Module.
Common causes: Common causes include Faulty Heating, Ventilation, and Air Conditioning (HVAC) Control Module, HVAC Control Module harness is open or shorted, HVAC Control Module 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 221

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 Jun 19, 2023

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code B3979 2015 GMC Sierra Description

When certain modules are programmed and configured during installation, the module learns a specific environment identifier which is unique to the vehicle. The environment identifier is used to prevent the swapping of control modules between vehicles. The Body Control Module (BCM) is the keeper of the environment identifier. The Instrument Cluster, Electronic Brake Control Module (EBCM), Heating, Ventilation, and Air Conditioning (HVAC) Control Module, Inflatable Restraint Sensing And Diagnostic Module, and Telematics Communication Interface Control Module each learn the environment identifier during their configuration process. During vehicle operation, the BCM sends the immobilizer identifier as a challenge and each module responds to the challenge by sending the environment identifier back to the BCM. If the BCM sends an incorrect immobilizer identifier or a specific number of incorrect environment identifiers are received, vehicle starting is disabled.

OBDII Code B3979 2015 GMC Sierra - Incorrect Environmental Identifier Received from HVAC Control Module - AutoCodes.com — B3979 2015 GMC Sierra Code - Incorrect Environmental Identifier Received from HVAC Control Module

What does this mean?

What are the Possible Causes of the DTC B3979 2015 GMC Sierra?

Faulty Heating, Ventilation, and Air Conditioning (HVAC) Control Module
HVAC Control Module harness is open or shorted
HVAC Control Module circuit poor electrical connection
Faulty Body Control Module (BCM)

How to Fix the DTC B3979 2015 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 B3979 2015 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 B3979 2015 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 B3979 2015 GMC Sierra Code

1. What are the common symptoms of OBDII code B3979 in a 2015 GMC Sierra?

- Common symptoms include erratic HVAC system operation, incorrect temperature readings, and a malfunctioning climate control system.

2. What does the OBDII code B3979 indicate in a 2015 GMC Sierra?

- This code indicates that the HVAC control module has received an incorrect environmental identifier, leading to issues with the climate control system.

3. What are the possible causes of OBDII code B3979 in a 2015 GMC Sierra?

- Possible causes include a faulty HVAC control module, wiring issues, communication errors between modules, or a software glitch in the vehicle's system.

4. How can I diagnose the OBDII code B3979 in my 2015 GMC Sierra?

- Diagnosis typically involves using a diagnostic scanner to retrieve the specific trouble code, checking for any related codes, and inspecting the HVAC control module and its connections.

5. Can I repair OBDII code B3979 in my 2015 GMC Sierra myself?

- Depending on your level of automotive expertise, you may be able to address this issue by checking and repairing any loose or damaged wiring connections, or by replacing the HVAC control module if necessary.

6. Is it safe to continue driving my 2015 GMC Sierra with OBDII code B3979 present?

- While the vehicle may still be operable, it is recommended to address the issue promptly to prevent further damage to the HVAC system and ensure proper climate control functionality.

7. How much does it typically cost to repair OBDII code B3979 in a 2015 GMC Sierra?

- Repair costs can vary depending on the exact cause of the issue and whether you choose to address it yourself or take it to a professional mechanic. Costs may range from a simple wiring repair to a replacement HVAC control module.

8. Can a software update fix OBDII code B3979 in a 2015 GMC Sierra?

- In some cases, a software update provided by the manufacturer may resolve the issue if it is related to a software glitch causing the incorrect environmental identifier to be received by the HVAC control module.

9. Will resetting the OBDII code B3979 clear the issue in my 2015 GMC Sierra?

- While clearing the code may temporarily remove the warning light, it is crucial to diagnose and address the underlying cause to prevent the issue from recurring.

10. How can I prevent OBDII code B3979 from occurring in the future in my 2015 GMC Sierra?

- Regularly maintaining your vehicle, checking for loose connections, and ensuring all software updates are applied can help prevent the recurrence of this code.