B3979 GMC 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 GMC 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.
Code B3979 GMC Description
What are the Possible Causes of the DTC B3979 GMC?
- 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 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 B3979 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.
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Information for Specific GMC Models
- B3979 2014 GMC Sierra — Incorrect Environmental Identifier Received from HVAC Control Module
- B3979 2015 GMC Sierra — Incorrect Environmental Identifier Received from HVAC Control Module
- B3979 2016 GMC Sierra — Incorrect Environmental Identifier Received from HVAC Control Module
- B3979 2017 GMC Sierra — Incorrect Environmental Identifier Received from HVAC Control Module
- B3979 2018 GMC Sierra — Incorrect Environmental Identifier Received from HVAC Control Module
Frequently Asked Questions about B3979 GMC Code
1. What are common symptoms of OBDII code B3979 GMC?
- Common symptoms include incorrect temperature readings on the HVAC display, inconsistent heating or cooling performance, and the HVAC system not responding to temperature adjustments.
2. What does the OBDII code B3979 GMC indicate?
- The code indicates that the HVAC control module has received an incorrect environmental identifier, which can lead to issues with temperature control and system operation.
3. What are possible causes of OBDII code B3979 GMC?
- Possible causes include a faulty HVAC control module, wiring or communication issues between the HVAC control module and other vehicle systems, or a software glitch within the system.
4. How can I diagnose OBDII code B3979 GMC?
- Diagnosis typically involves using a diagnostic scanner to retrieve the code, checking the HVAC control module for any visible damage or loose connections, and testing the communication between the module and other components.
5. Can I repair OBDII code B3979 GMC myself?
- Depending on your level of automotive knowledge, you may be able to address this issue by checking and repairing any visible wiring issues, ensuring proper connections, or resetting the HVAC control module. However, complex repairs may require professional assistance.
6. Is it safe to continue driving with OBDII code B3979 GMC present?
- While the vehicle may still be operable with this code present, it is recommended to address the issue promptly to prevent further HVAC system malfunctions or potential damage.
7. How much does it typically cost to repair OBDII code B3979 GMC?
- The cost of repair can vary depending on the exact cause of the issue. Simple fixes like resetting the module or repairing wiring may be relatively inexpensive, while replacing a faulty HVAC control module can be more costly.
8. Can weather conditions affect the occurrence of OBDII code B3979 GMC?
- Extreme temperature fluctuations or exposure to moisture can potentially exacerbate issues related to this code, so it's important to keep the HVAC system well-maintained and protected from environmental factors.
9. Will resetting the OBDII code B3979 GMC make it go away permanently?
- Resetting the code may temporarily clear it, but if the underlying issue is not addressed, the code is likely to reappear. It's important to diagnose and fix the root cause to prevent ongoing problems.
10. How long does it usually take to repair OBDII code B3979 GMC?
- The repair time can vary depending on the complexity of the issue and the availability of parts. Simple fixes may take just a short amount of time, while more involved repairs could require several hours or more.
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