B1D79 Code: Meaning, Causes, and Symptoms | OBD2 Codes

B1D79 – Microphone Input Circuit General Electrical Failure


B1D79 Possible Symptoms


Engine Light ON (or Service Engine Soon Warning Light)


B1D79 Possible Causes


Faulty Microphone,Microphone harness is open or shorted,Microphone circuit poor electrical connection,Faulty Audio Control Module (ACM) (if equipped),Faulty Accessory Protocol Interface Module (APIM) (if equipped)


B1D79 Description


When the VOICE switch is pressed, it changes a reference voltage signal, and the audio system enters voice recognition mode. The VOICE switch is wired to the Audio Control Module (ACM). The Accessory Protocol Interface Module (APIM) receives the microphone input and also broadcasts it to the ACM. The first voice commands spoken determine which system handles the voice commands. The microphone test is available through the ACM self-diagnostic mode (navigation only). Running this test causes the ACM to produce a test tone. If the system is operating correctly, the microphone detects the tone and produces a signal to the ACM indicating the tone was heard. The OBDII set by the ACM during the microphone test when it does not receive an adequate signal from the microphone when the test tone is sounded.