AutoCodes – GMC – B127C 2014 GMC Sierra

B127C 2014 GMC Sierra Code - Microphone 2 Input Signal Circuit

Quick Answer

The active noise cancellation system uses three microphones in the vehicle headliner: one above each front seating position, and one above the rear seat. Common causes include Faulty Radio Volume Compensator Interior Noise Microphone, Radio Volume Compensator Interior Noise Microphone harness is open or shorted, Radio Volume Compensator Interior Noise Microphone circuit poor electrical connection. Severity is Low - monitor the vehicle and repair when practical. The vehicle can usually be driven if no severe symptoms are present, but symptoms should be checked before extended driving.

What it means: B127C 2014 GMC Sierra indicates Microphone 2 Input Signal Circuit.
Common causes: Common causes include Faulty Radio Volume Compensator Interior Noise Microphone, Radio Volume Compensator Interior Noise Microphone harness is open or shorted, Radio Volume Compensator Interior Noise Microphone circuit poor electrical connection.
Severity: Low - monitor the vehicle and repair when practical.
Can I drive?: The vehicle can usually be driven if no severe symptoms are present, but symptoms should be checked before extended driving.

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Code Popularity 202

How popular is this code, among other codes? Low

Repair Importance Level

Low (Monitor) (1 / 3)

Repair Difficulty Level

Intermediate (2 / 3)

What is this?

Table of contents Created and updated by William Orellana on Nov 29, 2024

Description
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code B127C 2014 GMC Sierra Description

The active noise cancellation system uses three microphones in the vehicle headliner: one above each front seating position, and one above the rear seat. The Audio Amplifier provides a bias voltage to each microphone (+) and (-) signal circuit for the operation of the microphone. The microphones monitor the vehicle cabin for undesirable engine sounds. The Audio Amplifier uses the microphone inputs and an engine RPM signal to determine the frequency of the undesirable sound. The Diagnostic Trouble Code (DTC) will be set when a fault is detected on the specified (+) or (−) signal circuit for more than 1.5 seconds.

OBDII Code B127C 2014 GMC Sierra - Microphone 2 Input Signal Circuit - AutoCodes.com — B127C 2014 GMC Sierra Code - Microphone 2 Input Signal Circuit

What does this mean?

What are the Possible Causes of the DTC B127C 2014 GMC Sierra?

Faulty Radio Volume Compensator Interior Noise Microphone
Radio Volume Compensator Interior Noise Microphone harness is open or shorted
Radio Volume Compensator Interior Noise Microphone circuit poor electrical connection
Faulty Audio Amplifier

How to Fix the DTC B127C 2014 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 does this mean?

Code Tech Notes

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.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the B127C 2014 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.

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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 B127C 2014 GMC Sierra Code

1. What does the OBDII code B127C mean on a 2014 GMC Sierra?

B127C indicates an issue with the Microphone 2 Input Signal Circuit, which is related to the vehicle's hands-free or voice recognition system.

2. What are common symptoms of the B127C code?

Symptoms include poor or no voice recognition, malfunctioning hands-free phone operation, and potential error messages on the infotainment system.

3. What causes the B127C code to appear?

The code can be caused by a faulty microphone, damaged wiring or connectors in the microphone circuit, or an issue with the infotainment control module.

4. How can I diagnose the B127C code?

Start by inspecting the microphone and its wiring for visible damage or loose connections. Use a scan tool to verify the fault and test the circuit for continuity or short circuits.

5. Can I still use my hands-free system with a B127C code present?

In most cases, the hands-free system may not function properly, or voice commands may not be recognized.

6. How do I fix the B127C code on a 2014 GMC Sierra?

Repairs may involve replacing a faulty microphone, repairing damaged wiring, or reprogramming or replacing the infotainment control module if necessary.

7. Where is Microphone 2 located in the 2014 GMC Sierra?

Microphone 2 is typically located in the headliner or near the rearview mirror, depending on the trim and configuration of the vehicle.

8. Is the B127C code a serious issue?

While it wonâ€™t affect the drivability of the vehicle, it can hinder hands-free communication and voice recognition functions, which may be inconvenient.

9. Can a software update fix the B127C code?

In some cases, a software update to the infotainment system may resolve the issue if it is related to programming errors.

10. How much does it cost to repair the B127C code?

Repair costs vary depending on the root cause. Replacing a microphone may cost $50â€“$150, while module repairs or wiring fixes can be more expensive.