B1277:02 Code - Microphone 1 Input Signal Circuit Short to Ground
Quick Answer
For Cellular, Entertainment, and Navigation Systems: The Human Machine Interface Control Module uses the cellular telephone microphone for voice recognition and cellular features. Common causes include 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). 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
- B1277:02 indicates Microphone 1 Input Signal Circuit Short to Ground.
- Common causes
- Common causes include 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).
- 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.
Code B1277:02 Description
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.
What are the Possible Causes of the DTC B1277:02?
- 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)
How to Fix the DTC B1277:02?
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.
Code Tech Notes
What is the Cost to Diagnose the Code?
Labor: 1.0
To diagnose the B1277:02 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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Frequently Asked Questions about B1277:02 Code
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