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.
Vehicle Communication Interface Module
The vehicle communication interface module is a cellular device that allows the user to communicate data and voice signals over the national cellular network. Power is provided by a dedicated, fused B+ circuit. Ground is provided through the vehicle wiring harness attached to the module. The ignition state is determined by the vehicle communication interface module through serial data messaging.
Dedicated circuits are used to connect the vehicle communication interface module to a microphone, the button assembly and to command the status LED. The vehicle communication interface module communicates with the rest of the vehicle over the serial data bus.
The module houses 2 technology systems, one to process GPS data and another for cellular information. The cellular system connects the OnStar® system to the cellular carrier's communication system by interacting with the national cellular infrastructure. The module sends and receives all cellular communications over the cellular antenna and cellular antenna coax. GPS satellites orbiting earth are constantly transmitting signals of their current location. The OnStar® system uses the GPS signals to provide location on demand.
The module also has the capability of activating the horn, initiating door lock/unlock, slowing down stolen vehicle gradually or activating the exterior lamps using the serial data circuits. These functions can be commanded by the OnStar® Call Center per a customer request.
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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.
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