Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
OnStar Description and Operation (UI3): Microphone
The microphone is located in the headliner or roof console. The telematics communication interface control module supplies approximately 10V to the microphone on the microphone signal circuit. The microphone modifies the 10V depending on the volume and voice being detected. A microphone low reference circuit or a drain wire provides a ground for the microphone. The microphone signal circuits pass through the telematics communication interface control module to support entertainment voice recognition. Thus, the module uses the same microphone as the infotainment system. In the event the infotainment system uses two microphones only one will pass through the telematics communication interface control module.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.