AutoCodes – Generic – B127C

B127C 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 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 2,423

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 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 - Microphone 2 Input Signal Circuit - AutoCodes.com — B127C Code - Microphone 2 Input Signal Circuit

What does this mean?

What are the Possible Causes of the DTC B127C?

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?

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 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 B127C code?

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Need Help with the Code?

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Information for Specific Makes

B127C Buick — Microphone 2 Input Signal Circuit
B127C Cadillac — Microphone 2 Input Signal Circuit
B127C Chevrolet — Microphone 2 Input Signal Circuit
B127C Ford — Ambient Lighting Zone 2 Output Red LED Circuit
B127C GMC — Microphone 2 Input Signal Circuit
B127C Lincoln — Ambient Lighting Zone 2 Output Red LED Circuit
B127C Mercury — Ambient Lighting Zone 2 Output Red LED Circuit

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 Code

1. What are common symptoms of OBDII code B127C?

- Common symptoms of OBDII code B127C (Microphone 2 Input Signal Circuit) include a malfunctioning microphone, issues with the vehicle's hands-free calling system, and poor audio quality during phone calls.

2. What are possible causes of OBDII code B127C?

- Possible causes of OBDII code B127C include a faulty microphone, damaged wiring or connectors in the microphone circuit, issues with the hands-free calling system module, or a software glitch in the vehicle's communication system.

3. How can I diagnose OBDII code B127C?

- To diagnose OBDII code B127C, start by visually inspecting the microphone and its wiring for any visible damage. Use a multimeter to test the continuity of the wiring and connectors. Additionally, scan the vehicle's communication system for any related error codes.

4. Can I repair OBDII code B127C myself?

- Depending on your automotive repair skills, you may be able to repair OBDII code B127C yourself. Simple fixes may include replacing a faulty microphone or repairing damaged wiring. For more complex issues with the hands-free calling system module, it may be best to consult a professional mechanic.

5. Is it safe to continue driving with OBDII code B127C active?

- It is generally safe to continue driving with OBDII code B127C active, especially if the issue is related to the vehicle's microphone or hands-free calling system. However, it is recommended to address the problem promptly to ensure proper functionality of these features.

6. How much does it typically cost to repair OBDII code B127C?

- The cost to repair OBDII code B127C can vary depending on the specific cause of the issue. Simple repairs like replacing a microphone may cost around $50-$100, while more complex problems involving the hands-free calling system module could cost several hundred dollars.

7. Can OBDII code B127C affect other vehicle systems?

- OBDII code B127C is specific to the Microphone 2 Input Signal Circuit and is unlikely to directly affect other vehicle systems. However, if the issue is related to the vehicle's communication system, it may impact features like Bluetooth connectivity or voice commands.

8. Are there any preventative measures to avoid OBDII code B127C?

- To prevent OBDII code B127C, it is advisable to avoid physical damage to the microphone and its wiring. Regularly inspecting and maintaining the hands-free calling system can also help identify any potential issues before they escalate.

9. Will resetting the vehicle's computer clear OBDII code B127C?

- Resetting the vehicle's computer may temporarily clear OBDII code B127C, but if the underlying issue with the Microphone 2 Input Signal Circuit is not addressed, the code is likely to reappear. It is best to diagnose and repair the root cause of the problem.

10. Can extreme temperatures affect the occurrence of OBDII code B127C?

- Extreme temperatures can potentially affect the occurrence of OBDII code B127C by impacting the performance of the microphone or the wiring in the vehicle's communication system. It is important to monitor the system's functionality in varying conditions.