Engine-Codes - GMC - B1277 GMC

B1277 GMC Code - Microphone 1 Input Signal Circuit

- Code Popularity: 1,707 Views
- Repair Importance Level: 3/3
- Repair Difficulty Level: 3/3
Table of contents
ChatAC AutoCodes.com AI Chat

What are the Possible Causes of the DTC B1277 GMC?

NOTE: The causes shown may not be a complete list of all potential problems, and it is possible that there may be other causes.
  • Faulty Cellular Phone Microphone (For Cellular, Entertainment, and Navigation Systems)
  • Faulty Radio Volume Compensator Interior Noise Microphone (For Active Noise Cancellation System)
  • Faulty Audio Amplifier (For Active Noise Cancellation System)
  • Faulty Human Machine Interface Control Module or Radio (For Cellular, Entertainment, and Navigation Systems)

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.

⚠ Does your GMC have Safety Recalls? → Check here

How to Fix the DTC B1277 GMC?

Check the 'Possible Causes' listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector pins.

Search for B1277 GMC Questions and Answers: Search here →

What is the Cost to Diagnose the Code?

Labor: 1.0

The cost to diagnose the B1277 GMC code is 1.0 hour of labor. The diagnosis time and labor rates at auto repair shops vary depending on the location, make and model of the vehicle, and even the engine type. Most auto repair shops charge between $75 and $150 per hour.

What are Code Possible Symptoms?

  • Engine Light ON (or Service Engine Soon Warning Light)

What Does the B1277 GMC Code Mean?

For Cellular, Entertainment, and Navigation Systems:
The Human Machine Interface Control Module uses the cellular telephone microphone for voice recognition and cellular features. The Human Machine Interface Control Module provides a bias voltage to each microphone (+) and (-) signal circuit for the operation of the microphone.
The radio provides the cellular phone microphone with a supplied voltage on the cellular phone microphone high signal circuit. When the microphone is in use, voice data from the user is sent back to the radio on the cellular microphone low signal circuit.

For Active Noise Cancellation System:
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.

B1277 GMC Code - Microphone 1 Input Signal Circuit

Need more Information on the Code?

Need more information on how to fix the B1277 GMC code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the B1277 GMC code diagnosed by a professional: Find a repair shop in your area