Cellular Phone: Description and Operation

The OnStar(R) system on this vehicle is configured with either a version 2.0 or a version 2.6 system. Both the systems contain a Vehicle Interface Unit (VIU), Vehicle Communication Unit (VCU), GPS antenna, cellular antenna, microphone and OnStar(R) button assembly. Both the systems interface with the vehicle audio system.

The OnStar(R) system version 2.0 provides the customer with impact detection, navigation instructions, emergency services, stolen vehicle tracking and recovery service, roadside assistance, unlock doors, flash lights and pulse the horn.

The OnStar(R) system version 2.6 provides all the same features as version 2.0 with the addition of a hands free cellular phone. The OnStar(R) phone is a full featured cellular phone that uses voice commands for dialing and programming.

OnStar(R) Button Assembly
The OnStar(R) button assembly may be part of the rear view mirror on some vehicles and a separate unit on others. The button assembly is comprised of the 3 buttons and a status LED. The buttons are as follows:
^ The button with a "dot" when pressed allows the user to answer/end calls.
^ The OnStar(R) Call Center button (with the OnStar(R) logo) when pressed connects the user to the OnStar(R) call center.
^ The red Emergency button when pressed sends a high priority (emergency) call to the OnStar(R) call center.

The OnStar(R) button assembly receives ten volts on the keypad supply voltage circuit. Each of the buttons when pressed, completes the circuit across a resister allowing a specific voltage to be returned to the VIU on the keypad low reference circuit. Depending the voltage range returned, the VIU is able to identify which button has been pressed.

The OnStar(R) button assembly status LED is green when the system is on and operating normally. When the status LED is green and flashing, this means a call is in progress. When the LED is red, this indicates a system malfunction is present. The OnStar(R) LED is controlled by the VIU over the keypad LED red signal circuit and the keypad LED green signal circuit.

OnStar(R) Microphone
The OnStar(R) microphone can be part of the rear view mirror assembly or on some vehicle lines can be a separate unit. The users voice is transmitted from the microphone to the VIU over the cellular telephone microphone signal circuit.

Vehicle Interface Unit (VIU)
The VIU 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 GPS antenna plugs directly into the VIU. The VIU 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 VIU uses the entertainment and comfort serial data circuit. The VIU is supplied power from the battery positive voltage circuit. Power moding for the VIU is accomplished by a class 2 message on some vehicles or the ignition 1 voltage circuit on others. The VIU also has the capability of commanding the horn, door unlock and exterior lamps using the class 2 serial data circuit. For vehicles without that capability, the VIU uses specific circuits for commanding the horn, door unlock and exterior lamps. To mute the audio system the VIU uses either the class 2 serial data circuit on some vehicles and others use 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.

Vehicle Communication Unit (VCU)
The VCU is a 3 watt transceiver that connects the OnStar(R) system to the cellular carrier's communication system. The VCU handles all cellular communications. The cellular antenna plugs into the VCU. The VIU provides power and ground to the VCU. The VCU receives power from VIU on the battery positive voltage circuit. The VIU also supplies ignition voltage to the VCU over the ignition 1 voltage circuit. The VCU communicates with the VIU by using the OnStar(R) serial data (-) circuit, OnStar(R) serial data (+) circuit and the OnStar(R) serial data return circuit. The callers voice is carried to the VCU using the microphone signal circuit and the drain wire circuit. The audio signal is carried from the VCU to the VIU on the audio return signal circuit and the audio low reference circuit.

Hands Free Cellular Phone

Dialing A Phone Number Hands Free:

The hands free cellular phone is an additional feature to the OnStar system. During a hands free call the microphone and audio system work the same way as a normal OnStar(R) call. When the answer/end call button is pressed, the audio system will mute, the OnStar(R) system will then return the prompt "ready". At this point there is specific command set to initiate a cellular call. If the vehicle receives a call when the radio is on, the audio system will mute and an audible ring" will be heard though the speakers. The call will be answered when the answer/end call button is pressed.

All the voice activated commands are interpreted by the VIU. A list of these commands is supplied in the information provided to the customer. If the information is not available to reference, at any command prompt you can say "HELP" and the VIU will return an audible list of available commands. If the customer concern is not being understood or not being heard by the OnStar(R) system, place a call to the OnStar(R) Call Center to verify proper operation of the microphone. Here is an example of the commands and the OnStar(R) system responses.

A complete list of commands is supplied in the information provided to the customer with the OnStar(R) system.