The OnStar® system consists of the following components:

These components allow for wireless communications with the OnStar® Call center, and cellular phone calls performed with hands free voice recognition.

The OnStar® system is an integrated component in the vehicle, installed as a factory option. The Communication Interface Module (CIM) is interfaced directly with other modules on the class 2 bus, which allows for commanding outputs of other modules in addition limited remote diagnostics. The CIM is also interfaced via discrete wire to the radio allowing for sound from the OnStar® system. The most interactive of the modules is the Body Control Module (BCM), where the OnStar® CIM can perform functions such as unlock the doors, flash the DRLs with horn activation for up to 48 hours after the vehicle is locked and ignition key removed.

The proper operation of OnStar® is influenced by many factors outside of the vehicle. The System is dependent on cellular technology, Global Positioning System information, call center operation and vehicle component operation. Most of these systems are beyond the control and function of the limited on-board diagnostics. The importance of detailing the customers concern and checking with the support system to identify systems that were not functioning on the day of the failure will result in the proper diagnosis of the concern.

The OnStar® Remote Control 3-Button assembly is part of the inside rear view mirror (ISRVM) which allows the driver to contact the OnStar® Call Center. Each button determines a specific function such as normal OnStar® contact, call termination, placing outgoing cellular calls and emergency contact of OnStar®.

The Remote Control 3-Button assembly is supplied power from the CIM. Using a series of resistors, each button will return a different voltage to the CIM. The CIM will determine which button was pressed on the button assembly.

Diagnostic Telltale LED (Red or Green)

The mirror assembly has an LED, which is commanded either green or red for different states of diagnostics. The red LED on steady indicates a failure of the self-diagnostics, a flashing red and green LED indicates the CIM is performing self-diagnostic. This occurs during key up. The LED will illuminate green when self-diagnostics has passed and the system is ready for activation. If the module fails diagnostics and fails a DTC in the module, the red LED is the feedback to the customer, that the system is not functioning properly.

OnStar® Microphone

The remote microphone is located in the headliner near the driver. This is a direct input to the CIM respond to voice commands and to communicate with either the call center or external cellular calls.

Global Positioning System (GPS) Antenna

The GPS antenna is located on the rear glass. This is a direct input to the CIM, which provides the latitude and longitude of the vehicle. This allows the OnStar® call center to aid the customer with directions and location. The GPS antenna is a direct input to the CIM using a coax cable. The GPS antenna utilizes satellite information to determine the location of the vehicle. If trees, tall building and or other objects block the GPS signal, the system will not receive information to determine the location of the vehicle.

Operation of the Hands Free Cellular Phone

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 was as a normal OnStar® call. When the answer/end call button is pressed, the audio system will mute, the OnStar® system will then return the prompt READY. At this point there is a 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 through the speakers. The call will be answered when the answer/end call button is pressed.

All the voice activated commands are interpreted by the Communication Interface Module (CIM). 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 CIM will return an audible list of available commands. If the customer concern is not being understood or not being heard by the OnStar® system, place a call to the OnStar® Call Center to verify proper operation of the microphone. A complete list of commands is supplied in the information provided to the customer with OnStar® system.

OnStar® Sound and Radio Interface

The sound for the Onstar® system is routed through the vehicles audio system. This is accomplished through a single circuit the Audio Mute Line. This circuit is pulled to ground signaling the vehicle radio to enter Onstar® mode. At this time, the CIM sends sound through the speakers of the vehicle. While the radio is in Onstar® mode the radio will mute all other media allowing for sound from the Onstar® module. The volume control is set to a predetermined level when the Onstar® system is activated. Once Onstar® is active the volume level can be adjusted using the radio volume control

New Vehicle

The OnStar® system requires no special programming from neither the Saturn Service nor the Tech 2. All programming or customer profile setup is accomplished through the wireless connection to the OnStar® Cell Center. In order to set up a customer account, simply press the OnStar® button located on the inside rear view mirror and respond to the requests from the OnStar® advisor. The OnStar® call center will need personal information from the customer to activate the account. This information is provided after the vehicle is purchased.

Controller Replacement

Once diagnostics leads to an OnStar® controller replacement, the technician will need to place a call to the OnStar® call center and provide information from the label on the replacement controller. This information provided to OnStar® will allow the call center to recognize the new module and transfer the required personal information to the new controller. Each controller had a unique ID, which is required for OnStar® to recognize the controller when a call is placed. In addition to the numbers from the controller, the technician will provide the VIN from the vehicle along with the module information. The CIM information is available on the tools.

When diagnostics determine the Vehicle Communication Interface Module (CIM) requires replacement the technician must perform the following configuration with the Onstar® call center.

Important: This procedure must be performed in order for the Onstar® system to recognize the vehicle and the customer

1. Record the STID number from the label on the new Module (10 digits).
2. Record the ESN number from the label on the new Module (11 digits).
3. Install the new module CIM.
4. Press and hold the Onstar® "End Call" button (black with white dot) watch for the Onstar® LED status light to change from green to red to green.
5. After replacement, press the blue Onstar® button twice. When the Onstar® advisor responds, state that the vehicle has a new module and include the information that was recorded.
6. The vehicles VIN must be provided.
7. Return the CIM for core credit.