Part 1

OnStar Description and Operation

This OnStar(R) system consists of the following components:

* Telematics Communication Interface Module
* OnStar(R) button assembly
* Microphone
* Cellular antenna
* Navigation antenna
* Bluetooth (R) antenna (If Equipped)
* Back Up Battery (If Equipped)

This system also interfaces with the factory installed vehicle audio system.

Telematics Communication Interface Module

The telematics 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 telematics communication interface module through serial data messaging.

Dedicated circuits are used to connect the telematics communication interface module to a microphone, the button assembly, and to command the status LED. The telematics 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(R) 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(R) system uses the GPS signals to provide location on demand.

The module also has the capability of activating the horn, initiating door lock/unlock, or activating the exterior lamps using the serial data circuits. These functions can be commanded by the OnStar(R) Call Center per a customer request.

OnStar(R) Button Assembly

The OnStar(R) button assembly may be part of the rearview mirror, or a separate, stand alone unit. The button assembly is comprised of 3 buttons and a status LED. The buttons are defined as follows:

* The answer/end call button, which is black with a white phone icon, allows the user to answer and end calls or initiate speech recognition.
* The blue OnStar(R) call center button, which displays the OnStar(R) logo, allows the user to connect to the OnStar(R) call center.
* The emergency button, which displays a white cross with a red background, sends a high priority emergency call to the OnStar(R) call center when pressed.

The telematics communication interface module supplies 10 volts to the OnStar(R) button assembly on the keypad supply voltage circuit. When pressed, each button completes a circuit across a resistor allowing a specific voltage to be returned to the telematics communication interface module on the keypad signal circuit. Depending upon the voltage range returned the telematics communication interface module is able to identify which button has been pressed.

The OnStar(R) status LED is located with the button assembly. The LED is green when the system is ON and operating normally. When the status LED is green and flashing, it is an indication that a call is in progress. When the LED is red, this indicates a system malfunction is present. In the event there is a system malfunction and the OnStar(R) system is still able to make a call, the LED will flash red during the call.

If the LED does not illuminate, this may indicate that the customers OnStar(R) subscription is not active or has expired. Push the blue OnStar button to connect to an advisor who can then verify the account status.

Each LED is controlled by the telematics communication interface module over dedicated LED signal circuits. Ground for the LED is provided by the wiring harness attached to the button assembly.

Secondary OnStar(R) Controls

Some vehicles may have an additional button that when pushed can engage the OnStar(R) system. The button may be a symbol of a face with sound waves, or may say MUTE, or be a symbol of a radio speaker with a slash through it.

By engaging the OnStar(R) system with this feature, the user can interact with the system by use of voice commands. A complete list of these commands is supplied in the information provided to the customer. If the information is not available for reference, at any command prompt the user can say "HELP" and the telematics communication interface module will return an audible list of available commands.

OnStar(R) Microphone

The OnStar(R), or cellular phone microphone, can be a part of the rearview mirror assembly, or on some vehicle lines, a separate, stand alone unit. In either case, the telematics communication interface module supplies approximately 10 V to the microphone on the cellular phone microphone signal circuit, and voice data from the user is sent back to the telematics communication interface module over the same circuit. A cellular phone microphone low reference circuit or a drain wire provides a ground for the microphone.

Cellular and GPS Antennas

This vehicle will be equipped with one of the following types of antennas:

* Separate, standalone cellular and navigation antennas
* A combination cellular and navigation antenna, which brings the functions of both into a single part
* A cellular, GPS, and digital radio receiver antenna, which also incorporates the functionality of the digital radio receiver satellite antenna (XM).
* A cellular, GPS, and digital radio receiver antenna, which also incorporates the AM/FM antenna.

The cellular antenna is the component that allows the OnStar(R) system to send and receive data over airwaves by means of cellular technology. The antenna is connected at the base to a coax cable that plugs directly into the telematics communication interface module.

The GPS antenna is used to collect the signals of the orbiting GPS satellites. Within the antenna is housed a low noise amplifier that allows for a more broad and precise reception of this data. The antenna is connected at the base to a coax cable that plugs directly into the telematics communication interface module. The cable also provides a path for DC current for powering the antenna.

The OnStar(R) Call Center also has the capability of communicating with the vehicle during an OnStar(R) call to retrieve the latest GPS location and transmit it to the OnStar(R) Call Center. A history location of the last recorded position of the vehicle is stored in the module and marked as aged, for as long as the module power is not removed. Actual GPS location may take up to 10 minutes to register in the event of a loss of power.

Cellular and Navigation Signal Antenna Splitter

The navigation signal Splitter is a component for dividing the navigation signal antenna signal into two paths without any transmission loss. It has two RF-connectors, one signal fakra-connector and one double fakra connector. Port 1 is the input for connecting tot he navigation signal antenna, port 2 is the output for the car OnStar navigation system, port 3 is the output for the navigation radio. Port 1 and 2 are galvanically coupled internally using a matching network. The OnStar system supplies the navigation signal antenna with power via port 2. Connectivity is made between port 1 and 3 though and internal coupling element and low noise amplifier. The navigation radio provides the amplifier with power via port 3.