Vehicle Communication Interface Module (VCIM)

The Vehicle Communication Interface Module for the OnStar(R) system contains a GPS receiver and a cellular modem. The GPS receiver determines the vehicles location using the GPS satellite system. The navigation antenna which receives the GPS signal plugs directly into the VCIM. The navigation antenna requires a clear and unobstructed path to the satellites in the sky. Window tinting on vehicles may interfere with the GPS sensor functions, depending on the amount of darkening and/or metallic particles which are embedded in the film of the tinting material. The Vehicle Communication Interface Module communicates with the rest of the vehicle over the class 2 serial data bus. On vehicles that do not use class 2 to communicate with the audio system, the VCIM uses the entertainment and comfort serial data circuit. The module is powered from the battery positive voltage circuit, and power moding is accomplished by either a class 2 message or the ignition 1 voltage circuit. The module also has the capability of commanding the horn, door lock/unlock and exterior lamps using the class 2 serial data circuit. For vehicles without this capability, the VCIM uses specific circuits for commanding these functions. To mute the audio system, the Vehicle Communication Interface Module uses either the class 2 serial data circuit or the entertainment and comfort serial data circuit. After the audio system is muted, the OnStar(R) audio is transmitted to the vehicles audio system on the remote audio output (-), remote audio right signal circuit, and the remote audio left signal circuit. The VCIM is a 3 watt transceiver that connects the OnStar(R) system to the cellular carrier's communication system. The module handles all cellular communications over the cellular antenna and cellular antenna coax, which plugs directly into the module.