Engine-CodesGMC – B127C 2018 GMC Sierra

B127C 2018 GMC Sierra Code - Microphone 2 Input Signal Circuit

Quick Answer

The B127C diagnostic trouble code for a 2018 GMC Sierra relates to the Microphone 2 Input Signal Circuit. Common causes include Faulty microphone, Damaged wiring or connectors related to the microphone, Malfunctioning audio control module. 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
B127C 2018 GMC Sierra indicates Microphone 2 Input Signal Circuit.
Common causes
Common causes include Faulty microphone, Damaged wiring or connectors related to the microphone, Malfunctioning audio control module.
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.
Table of contents Created and updated by William Orellana on Sep 14, 2024
💬 Need more help? Ask Auto Expert for instant answers — it's free!
AutoCodes App

Fix Your Car Smarter

Try the New AutoCodes App!

Get complete OBDII diagnostics, repair solutions, and cost estimates, plus AI chat support on demand.

AutoCodes App on Google Play

Code B127C 2018 GMC Sierra Description

The B127C diagnostic trouble code for a 2018 GMC Sierra relates to the Microphone 2 Input Signal Circuit. This code indicates that there is a problem with the signal being received from the second microphone in the vehicle. The microphone input signal is crucial for various systems in the vehicle, including hands-free calling, voice commands, and possibly even the vehicle's noise cancellation features. When this signal is compromised, it can lead to issues with communication systems and overall user experience inside the vehicle.

OBDII Code B127C 2018 GMC Sierra - Microphone 2 Input Signal Circuit
B127C 2018 GMC Sierra Code - Microphone 2 Input Signal Circuit

Common Causes of B127C 2018 GMC Sierra

  1. Faulty microphone.
  2. Damaged wiring or connectors related to the microphone.
  3. Malfunctioning audio control module.
  4. Software glitch in the vehicle's communication system.
  5. Water damage or corrosion affecting the microphone circuit.

Symptoms of B127C 2018 GMC Sierra

  1. Loss of functionality in hands-free calling or voice command systems.
  2. Poor audio quality during phone calls or voice commands.
  3. Inability to use noise cancellation features effectively.
  4. Error messages related to microphone input signal.

How to Fix B127C 2018 GMC Sierra

  1. Begin by conducting a thorough inspection of the microphone, wiring, and connectors to identify any visible damage or issues.
  2. Test the microphone and its connections using a multimeter to check for proper functionality.
  3. If the microphone is found to be faulty, replace it with a new one following the manufacturer's guidelines.
  4. Check and repair any damaged wiring or connectors in the microphone circuit.
  5. If the issue persists, further diagnostics may be required to identify potential problems with the audio control module or software.

Cost to Fix B127C 2018 GMC Sierra

The typical repair costs for addressing the B127C code on a 2018 GMC Sierra can vary depending on the specific cause of the issue. Generally, replacing a faulty microphone or repairing damaged wiring may cost between $100 to $300, including parts and labor. However, if the problem is more complex and involves the audio control module or software, the repair costs could range from $300 to $800 or more. It's important to consider the specific diagnosis time and labor rates at auto repair shops, which can vary based on location and other factors. It's advisable to consult with a professional technician for an accurate cost estimate tailored to your vehicle's needs.

Tech Notes for B127C 2018 GMC Sierra

Installation of aftermarket replacement speakers, additional speakers/subwoofers, or aftermarket exhaust systems can cause undesirable behavior of the active noise cancellation system. The noise reduction microphones have foam blocks above them to seal the microphones and aid in the reduction of headliner vibration. Missing or out of place foam blocks can impact system performance.

Need more information about the B127C 2018 GMC Sierra code?

Need more information on how to fix the B127C 2018 GMC Sierra code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the B127C 2018 GMC Sierra 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 B127C 2018 GMC Sierra Code

1. What does the OBDII code B127C mean on a 2018 GMC Sierra?

The code B127C indicates an issue with the Microphone 2 Input Signal Circuit, typically related to a fault in the wiring, connections, or the microphone itself.

2. What are the symptoms of code B127C in a 2018 GMC Sierra?

Symptoms may include poor audio quality during voice commands or phone calls, inability to use voice recognition features, or no input from the secondary microphone.

3. What causes the B127C code on a GMC Sierra?

Common causes include a faulty microphone, damaged wiring or connectors, or a malfunctioning infotainment system.

4. Can I still drive my 2018 GMC Sierra with a B127C code?

Yes, this code typically does not affect vehicle drivability but may impair hands-free communication and voice recognition functionality.

5. How can I fix the B127C code on my GMC Sierra?

Check the wiring and connectors for damage, ensure the microphone is securely connected, and replace the microphone if it is defective.

6. Where is Microphone 2 located in a 2018 GMC Sierra?

Microphone 2 is usually located in the vehicle’s headliner near the driver or passenger side, depending on the configuration.

7. How much does it cost to repair a B127C code on a GMC Sierra?

Repair costs can vary but typically range from $50 to $200, depending on whether the issue is with the microphone or wiring.

8. Can a software update fix the B127C code?

In some cases, a software update for the infotainment system may resolve the issue if it’s related to a system glitch.

9. Do I need special tools to diagnose the B127C code?

While a basic OBDII scanner may identify the code, advanced diagnostic tools or a multimeter will be needed to test the wiring and microphone.

10. Should I take my GMC Sierra to a mechanic for a B127C code?

If you’re unable to diagnose or repair the issue yourself, it’s best to consult a certified technician to avoid further complications.

Discuss the causes and fixes for B127C 2018 GMC Sierra OBDII Code

Code B127C 2018 GMC Sierra comments

No comments found for this page.