Cellular Communication System Buick Century VI

Specifications

Fastener Tightening Specifications

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Diagnostic Starting Point-Cellular Communication

Begin the system diagnosis with DIAGNOSTIC SYSTEM CHECK-CELLULAR COMMUNICATION .

The Diagnostic System Check will provide the following information

1. The identification of the control modules which command the system
2. The ability of the control modules to communicate through the serial data circuit
3. The identification of any stored diagnostic trouble codes (DTCs) and their status

The use of the Diagnostic System Check will identify the correct procedure for diagnosing the system and where the procedure is located.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

1. 2. Lack of communication may be due to a partial malfunction or a total malfunction of the class 2 serial data circuit. The specified procedure will determine the condition.
2. 3. The presence of DTCs which begin with "U" indicate some other system control module is not communicating.

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Scan Tool Data Definitions

Module Information-Software Version: This displays the 3-digit number of the software version used on the OnStar® VCIM.

Module Information Hardware Version: This displays the 1-digit number of the hardware version used on the OnStar® VCIM.

Module Information-Julian Date Of Build: This displays the day of the year the module was built.

Module Information-Year Module Built: This displays the year the module was built.

Module Information-8-Digit GM Part Number: This displays the part number for the VCIM.

Module Information-Component Serial #8: This is the first partition of the serial number.

Module Information-Component

Serial #12: This is the second partition of the serial number.

Module Information-Component

Serial #13: This is the third partition of the serial number.

VCI Module Station Identification

Number (STID): This is the station identification number stored in the VCIM which is used by the OnStar® Call Center.

Module ID: This displays the version of OnStar® which the vehicle is equipped with.

Electronic Serial Number (ESN): This is the electronic serial number stored in the VCIM which is used by the OnStar® Call Center

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Circuit Description

The Vehicle Communication Interface Module detects that the Cellular Microphone is connected through the Cellular Microphone Signal circuit and the drain wire.

Conditions for Running the DTC

1. The ignition must be in the RUN or ACC position.
2. The system voltage is at least 9.5 volts and no more than 15.5 volts.
3. All the above conditions are present for greater than 10 seconds.

Conditions for Setting the DTC

1. The Vehicle Communication Interface Module detects an open in the Drain Wire circuit or a short to voltage in the Cellular Microphone Signal circuit.
2. The above conditions are present for greater than 10 seconds.

Action Taken When the DTC Sets

1. The Vehicle Communication Interface Module will not receive any signal from the microphone.
2. Calls can be placed but the caller cannot be heard.
3. The OnStar® status LED turns RED.

Conditions for Clearing the DTC

1. The Vehicle Communication Interface Module detects the microphone connected for 5 consecutive 100 millisecond cycles.
2. A history DTC clears after 50 malfunction free ignition cycles.
3. The Vehicle Communication Interface Module receives the clear DTC command from the scan tool.

The number below refers to the step number on the diagnostic table.

1. 2. This step checks that the Vehicle Communication Interface Module is sending out the proper supply voltage.

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The Cellular Antenna is connected to the Vehicle Communication Interface Module with a RG-58 coax cable. The Vehicle Communication Interface Module polls the data from the cellular antenna once every second.

1. The ignition must be in the RUN or ACC position.
2. The system voltage is at least 9.5 volts and no more than 15.5 volts.
3. All the above conditions are present for greater than 1 second.

1. The Vehicle Communication Interface Module does not detect a cellular signal.
2. All the above conditions are present for greater than 1 second.

1. The OnStar® status LED turns RED.
2. The vehicle is unable to connect to the OnStar® Call Center.

1. The Vehicle Communication Interface Module detects the presence of a Cellular Antenna.
2. A history DTC clears after 50 malfunction free ignition cycles.
3. The Vehicle Communication Interface Module receives the clear DTC command from the scan tool.

The number(s) below refer to the step number(s) on the diagnostic table.

1. 2. This step tests the condition of the Cellular Antenna.
2. 3. This step tests the condition of the cellular antenna coax and for proper ground of the cellular antenna.

Scheme 88

The OnStar® button assembly consists of three buttons, Call/Answer, OnStar® Call Center and OnStar® Emergency. Ten volts is supplied to the button assembly 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 Vehicle Communication Interface Module on the Keypad Signal circuit. Depending upon the voltage range returned, the Vehicle Communication Interface Module is able to identify which button has been pressed.

1. The ignition must be in the RUN or ACC position.
2. The system voltage is at least 9.5 volts and no more than 15.5 volts.
3. All the above conditions are present for greater than 300 ms.

1. The Keypad Signal circuit voltage to the Vehicle Communication Interface Module is less than 2.8 volts or more than 3.2 volts.
2. The above conditions are present for greater than 300 ms.

1. The Vehicle Communication Interface Module will ignore all inputs from the OnStar® button assembly.
2. No calls can be placed.
3. The OnStar® status LED turns RED.

1. The Keypad Signal circuit voltage is between 2.8 volts and 3.2 volts.
2. A history DTC clears after 50 malfunction free ignition cycles.
3. The Vehicle Communication Interface Module receives the clear DTC command from the scan tool.

The number below refers to the step number on the diagnostic table.

1. 2. This step checks that the Vehicle Communication Interface Module is sending out the proper supply voltage.

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The OnStar® button assembly consists of three buttons, Call/Answer, OnStar® Call Center and OnStar® Emergency. Ten volts is supplied to the button assembly 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 Vehicle Communication Interface Module on the keypad signal circuit. Depending upon the voltage range returned, the Vehicle Communication Interface Module is able to identify which button has been pressed.

1. The ignition must be in the RUN or ACC position.
2. The system voltage is at least 9.5 volts and no more than 15.5 volts.
3. All the above conditions are present for greater than 15 seconds.

1. A button is depressed or stuck for more than 15 seconds.
2. The above conditions are present for greater than 15 seconds.

1. The Vehicle Communication Interface Module will ignore all inputs from the OnStar® button assembly.
2. No calls can be placed.
3. The OnStar® status LED turns RED.

1. The button will be declared unstuck after a 50 ms normal cycle.
2. A history DTC clears after 50 malfunction free ignition cycles.
3. The Vehicle Communication Interface Module receives the clear DTC command from the scan tool.

The number below refers to the step number on the diagnostic table.

1. 2. This step tests the at rest state of the Keypad Signal circuit.

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The Navigation Antenna is connected to the Vehicle Communication Interface Module with a RG-174 coax cable. The Vehicle Communication Interface Module polls the data from the Navigation antenna once every second.

1. The ignition must be in the RUN or ACC position.
2. The system voltage is at least 9.5 volts and no more than 15.5 volts.
3. All the above conditions are present for greater than 1 second.

1. The Vehicle Communication Interface Module does not detect a Navigation signal.
2. All the above conditions are present for greater than 1 second.

1. The OnStar® status LED turns RED.
2. The OnStar® Call Center cannot locate the vehicle.

1. The Vehicle Communication Interface Module detects the presence of a Navigation antenna.
2. A history DTC clears after 50 malfunction free ignition cycles.
3. The Vehicle Communication Interface Module receives the clear DTC command from the scan tool.

The number below refers to the step number on the diagnostic table.

1. 2. This step tests the condition of the Navigation Antenna

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This vehicle utilizes both a Class 2 and Entertainment and Comfort Serial Data line for communication with the OnStar® Vehicle Communication Interface Module (VCIM). Class 2 messaging is utilized for inter-module information transfer to support features such as remote door locking and unlocking. Because this vehicle does not utilize a Class 2 supported radio, the E & C data line must be implemented to transfer the OnStar® audio signals from the VCIM to the vehicle audio system. In the event the Entertainment and Comfort Serial Data line is shorted to ground, shorted to voltage or opened, U1306 is set as current and can be read through the use of the scan tool over the Class 2 Serial Data line. Calls will still be placed to the OnStar® Call Center if a keypress is make, however, no OnStar® audio will be heard and the radio will not mute if currently turned on.

1. The ignition must be in the RUN or ACC position, or retained accessory power (RAP) must be active.
2. The system voltage is at least 9.5 volts and no more than 15.5 volts.
3. All of the above conditions are present for greater than 300 ms.

1. The VCIM does not communicate with the radio.
2. No OnStar® audio is heard and the radio will not mute after a keypress is made.
3. The OnStar® status LED turns Red.

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1. The VCIM does not detect a short to ground on the Entertainment and Comfort Serial Data Bus
2. The VCIM does not detect a short to voltage on the Entertainment and Comfort Serial Data Bus
3. The VCIM does not detect an open in the Entertainment and Comfort Serial Data Bus
4. A history DTC clears after 50 malfunction free ignitions cycles
5. The VCIM detects the clear DTC command from the scan tool

This DTC indicates an internal fault and is set within the vehicle communication interface module (VCIM). No external circuits are involved.

The microprocessor runs the program to detect an internal fault during module power up and every 10 seconds thereafter until the module re-enters the sleep mode.

The VCIM detects an internal communication malfunction.

Action Taken When DTC Sets

1. The OnStar® status LED turns RED.
2. The vehicle is unable to connect to the OnStar® Call Center.

1. A current DTC clears when the malfunction is no longer present.
2. A history DTC clears after 50 malfunction free ignition cycles.

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1. The diagnostic procedure used for DTC U1500 in OnStar® systems with single module generations of OnStar® differ greatly from previous generations with two modules. While these older generations denoted a failure of the three wire bus between the modules by setting a U1500, single module OnStar® systems use this DTC to denote an internal module failure. The determination of whether a one or two module generation of OnStar® is used should be confirmed. Refer to «ONSTAR DESCRIPTION AND OPERATION»(/buick/century/vi-1997-2005/remont/entertainment-systems/#cellular-communication-system__onstar-description-and-operation) .
2. This DTC may be stored as a history DTC without affecting the operation of the module. If stored only as a history DTC and not retrieved as a current DTC, do not replace the VCIM.
3. If this DTC is retrieved as both a current and history DTC, replace the VCIM.

System Description

This symptom table will enable the user to verify the customer complaint and narrow it to its source. If there is a concern with voice recognition or OnStar® steering wheel control function, technicians should proceed directly to the applicable diagnostic in SYMPTOMS-CELLULAR COMMUNICATION .

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1. The customer concern may have been due to a lack of cellular service in a given area or a failure in the National Cellular Network infrastructure that has since been corrected.
2. If the prompt OnStar Request Ended is heard without depressing the white dot button at the end of the an OnStar® keypress, the OnStar® system at one time has made a successful cellular connection but was unable to complete the call. If repeated calls are placed with this result, contact the General Motors Technical Assistance Center.
3. Inaccurate or aged Global Positioning System (GPS) position may have been due to the temporary loss of GPS signal reception by the vehicle in instances such as driving through tunnels or parking structures which restrict the navigation antenna from a clear view of the satellites in the sky.

Symptoms-Cellular Communication

1. Perform the «DIAGNOSTIC SYSTEM CHECK-CELLULAR COMMUNICATION»(/buick/century/vi-1997-2005/remont/entertainment-systems/#cellular-communication-system) before using the Symptom Tables in order to verify that all of the following are true: There are no DTCs set. The control module can communicate via the serial data link.
2. Review the system operation in order to familiarize yourself with the system functions. Refer to «ONSTAR DESCRIPTION AND OPERATION»(/buick/century/vi-1997-2005/remont/entertainment-systems/#cellular-communication-system__onstar-description-and-operation) .

Visual/Physical Inspection

1. Inspect for aftermarket devices which could affect the operation of the system. Refer to «CHECKING AFTERMARKET ACCESSORIES»(/buick/century/vi-1997-2005/remont/body-electrical/#wiring-systems__checking-aftermarket-accessories) in Wiring Systems.
2. Inspect the easily accessible or visible system components for obvious damage or conditions which could cause the symptom.

Intermittent

Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to TESTING FOR INTERMITTENT AND POOR CONNECTIONS in Wiring Systems.

Symptom List

Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom

1. «OnStar One or More Buttons Inoperative»(/buick/century/vi-1997-2005/remont/entertainment-systems/#cellular-communication-system)
2. «UNABLE TO CONTACT ONSTAR CALL CENTER»(/buick/century/vi-1997-2005/remont/entertainment-systems/#cellular-communication-system)
3. «ONSTAR BUTTON LED INOPERATIVE»(/buick/century/vi-1997-2005/remont/entertainment-systems/#cellular-communication-system)
4. «NO (OR NOISY) ONSTAR AUDIO»(/buick/century/vi-1997-2005/remont/entertainment-systems/#cellular-communication-system)
5. «Microphone Inoperative - Caller Cannot Be Heard»(/buick/century/vi-1997-2005/remont/entertainment-systems/#cellular-communication-system)
6. «Voice Recognition Inoperative»(/buick/century/vi-1997-2005/remont/entertainment-systems/#cellular-communication-system)
7. «GLOBAL POSITIONING SYSTEM (GPS) DATA NOT CURRENT OR INACCURATE»(/buick/century/vi-1997-2005/remont/entertainment-systems/#cellular-communication-system)

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1. The customer concern may have been due to a lack of cellular service in a given area. A failure in the National Cellular Network infrastructure at the time of the customer's failed connection that has since been repaired may also have been the cause.
2. If an OnStar Emergency call is able to successfully connect the vehicle to the OnStar Call Center when an OnStar Call Center button press is not, there may be a failure in the ability of the OnStar system in the vehicle to be recognized by the local cellular carrier.
3. If the prompt "OnStar request ended" is heard without depressing the white "Dot" button at the end of the an OnStar keypress, the OnStar system at one time has made a successful cellular connection but was unable to complete the call. If repeated calls are placed with this result, contact the General Motors Technical Assistance Center.

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The numbers below refer to the step numbers on the diagnostic table.

1. 3. Determines if the OnStar® status LED has the necessary Green LED signal circuit voltage.
2. 5. If the Green LED signal is shorted to voltage then the OnStar® three button assembly has been damaged and the OnStar® three button assembly must be replaced.

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The number below refers to the step number on the diagnostic table.

1. 7. If the Cellular Telephone Voice Low Reference circuit is shorted to voltage the Vehicle Communication Interface Module has been damaged and requires replacement.

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1. If the OnStar® Call Center has not received any GPS data, this is an indication that the OnStar® call was a fail to voice and may be due to a failure in the National Cellular Network infrastructure. If this occurs, contact the General Motors Technical Assistance Center.
2. Inaccurate or aged GPS position concerns made by a customer which are no longer present may have been due to the temporary loss of GPS signal reception by the vehicle. Conditions such as driving through tunnels or parking structures while making an OnStar® keypress will restrict the navigation antenna from a clear view of the satellites in the sky and may have caused this temporary data loss.

Removal Procedure

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1. Disconnect the coaxial cable from the mobile communication antenna inner coupling. NOTE: If you use a razor blade or other sharp tool in order to remove the adhesives or foreign objects from the inside of the rear window, use the blade carefully. Damage to the grid lines may result.
2. Use a small wide-bladed plastic tool to cut the double back tape material while lifting up on the inner antenna coupling (2).

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1. Clean the inside of the back glass with an alcohol wipe.
2. Dry the glass thoroughly using a lint free cloth.
3. Apply Glass Adhesion Promoter GM P/N 12378555, (Canadian P/N 88901239), to the back glass in the area where you will install the antenna coupling. Follow the Glass Adhesion Promoter instructions on the product label. IMPORTANT: The RF connections for the inner antenna coupling should run parallel to the defogger gridline. Align the inner and outer antenna couplings. Do not touch the adhesive backing on the antenna coupling.
4. If the exterior coupling is not installed, mark the inner antenna coupling location (A) 92 mm (3.75 in) and (B) 80 mm (3.25 in) with a grease pencil on the exterior surface of the rear window.
5. Remove the protective film from the adhesive backing on the inner antenna coupling.
6. Align the inner antenna coupling to the locating marks on the back glass or the exterior coupling.
7. Press firmly on all 4 corners and on the center of the antenna inner coupling (2) in order to ensure proper adhesion to the back glass (4). Hold pressure on the inner coupling (2) for 10-30 seconds.
8. Ensure there are not any gaps between the couplings (5, 2) and the back glass (4).
9. Connect the coaxial cable to the inner coupling.
10. Keep the vehicle dry. Allow 6-8 hours, at 15°C (60°F), for the adhesive to cure after installation.

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1. Install the inner coupling first if both the inner and the outer coupling are to be replaced. Refer to «COUPLING REPLACEMENT-ANTENNA INNER»(/buick/century/vi-1997-2005/remont/entertainment-systems/#cellular-communication-system) . NOTE: If you use a razor blade or other sharp tool in order to remove the adhesives or foreign objects from the inside of the rear window, use the blade carefully. Damage to the grid lines may result.
2. Use a small wide-bladed plastic tool to cut the double back tape material while lifting up on the outer antenna coupling (5).

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1. Clean back glass with an alcohol wipe.
2. Dry the glass thoroughly using a lint free cloth.
3. Apply Glass Adhesion Promoter GM P/N 12378555, (Canadian P/N 88901239) to the back glass in the area where you will install the antenna coupling. Follow the Glass Adhesion Promoter instructions on the product label. IMPORTANT: Align the inner and outer antenna couplings. Do not touch the adhesive backing on the antenna coupling.
4. Remove the protective film from the adhesive backing on the outer antenna coupling.
5. Align the outer antenna coupling to the inner antenna coupling.
6. Press firmly on all 4 corners and on the center of the antenna outer coupling (5) in order to ensure proper adhesion to the back glass (4). Hold pressure on the outer coupling (5) for 10-30 seconds.
7. Ensure that no gaps occur between the couplings (5, 2) and the back glass (4).
8. Keep the vehicle dry. Allow 6-8 hours, at 15°C (60°F), for the adhesive to cure after installation.

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1. Remove the rear shelf trim panel. Refer to TRIM PANEL REPLACEMENT - REAR WINDOW SHELF in Interior Trim.
2. Use a small wide-bladed plastic tool to release the adhesive. Remove the global positioning system (GPS) antenna from the rear shelf.
3. Disconnect the GPS antenna cable connector.
4. Clean the adhesive residue from the rear shelf using a razor blade, an isopropyl alcohol pad, and a clean lint-free cloth.

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1. Clean the surface of the rear shelf in the GPS antenna mounting location, using an isopropyl alcohol pad and a clean lint-free cloth. IMPORTANT: Do not touch the adhesive backing.
2. Remove the protective backing from the adhesive of the GPS antenna.
3. Install the GPS antenna to the rear shelf surface. Press the GPS antenna into place for approximately 30 seconds until fully seated.
4. Connect the GPS antenna cable connector.
5. Install the rear shelf trim panel. Refer to TRIM PANEL REPLACEMENT - REAR WINDOW SHELF in Interior Trim.

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1. Open the rear compartment.
2. Remove the black plastic OnStar® cover.
3. Remove the communication interface module nuts.
4. Adjust the assembly for access.
5. Disconnect the cellular antenna cable from the communication interface module by pulling outward on the square plastic housing.
6. Disconnect the 2 lower connectors from the module.
7. Disconnect the GPS antenna cable from the module by pulling outward on the circular metal sleeve.
8. Disengage the 2 large, plastic snap features at the inboard edge of the metal bracket, allowing the plastic bracket assembly to drop.
9. Push the plastic bracket assembly slightly outboard. Unhook the outboard plastic tabs.
10. Slide the plastic bracket assembly inboard, under the metal bracket. Remove the plastic bracket assembly from the metal bracket.
11. On bottom side of plastic bracket assembly, directly below the 2 large, plastic snap features, locate the under cut edge. Pull this under cut edge outward, up and over the side of the module.
12. Note the orientation of the module in the plastic bracket for installation. Slide the module out of the plastic bracket.

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1. If you are replacing the VCIM, record the 10-digit standard identification (STID) number and the 11-digit electronic serial number (ESN) from the labels on the new module.
2. Align the connector side of the module to the large cutout on the plastic bracket. Insert the module into the plastic bracket. Make sure the small GPS connector is inserted into the small round hole in the plastic bracket.
3. Spread the large tang side of the plastic bracket over the edge of the module. The bottom, undercut edge of the plastic bracket will snap over the bottom of the module when fully seated.
4. The connectors on the module must be outboard. Slide the plastic bracket assembly outboard, under the metal bracket.
5. Engage the outboard plastic tabs to the outboard edge of the metal bracket.
6. Squeeze the plastic bracket assembly upward until the large, plastic snap-fingers engage on the inboard edge of the metal bracket. NOTE: Before you install the antenna cable connector of the global positioning system (GPS) to the vehicle communication interface module (VCM), align the connector properly in order to avoid damaging the connector.
7. Gently connect the GPS antenna cable to the module by pushing inward on the circular metal sleeve.
8. Connect the 2 lower connectors to the module.
9. Connect the cellular antenna cable to the module by pushing inward on the square plastic housing. IMPORTANT: After replacing the vehicle communication interface module, you must reconfigure the OnStar® system. Failure to reconfigure the system will result in an additional customer visit for repair. In addition, pressing and holding the white dot button on the keypad will NOT reset this version of the OnStar® system. This action will cause a DTC to set.
10. Install the scan tool. Use the special functions menu in order to perform the OnStar® setup procedure for this vehicle.
11. Move the vehicle to an open area that is away from tall buildings and with a clear view of unobstructed sky. Allow the vehicle to run for 10 minutes.
12. Use the ID information menu on the scan tool to access the new station ID (STID) and the electronic serial number (ESN) from the new VCIM.
13. Press the blue OnStar® button to connect to the OnStar® Call Center and perform the following procedure: 13.1. Tell the advisor that this vehicle has received a new VCIM. 13.2. Ask the advisor to add the new STID and the ESN to update the customer's account. 13.3. Follow any additional instructions from the OnStar® advisor. 13.4. Ask the advisor to activate the OnStar® Personal Calling feature, if available.
14. Position the assembly to the studs. NOTE: Refer to «FASTENER NOTICE»(/buick/century/vi-1997-2005/remont/oem-general-information/#gm-vehicles-cautions-notices__fastener-notice) in Cautions and Notices.
15. Install the communication interface module nuts. Tighten Tighten the nuts to 4 N.m (35 lb in).
16. Install the plastic OnStar® cover.
17. Close the rear compartment.

OnStar Description and Operation

This vehicle uses the F1 version of the OnStar® system. This system consists of the following components

1. Vehicle Communication Interface Module (VCIM)
2. OnStar® button assembly
3. Microphone
4. Cellular antenna
5. Navigation antenna

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

Vehicle Communication Interface Module (VCIM)

The VCIM is a 3-watt cellular device that allows the user to communicate data and voice signals over the national cellular network. It is powered by a fused, battery positive voltage circuit, connected through vehicle wiring to the 3-button assembly and the radio, and attached by means of coax cables to the cellular and navigation antennas. Ground for the module is accomplished by means of dedicated circuits that are routed with body wiring systems to chassis ground points. The module houses two modems, one to process GPS data, and the other for cellular information. Satellites orbiting earth are constantly transmitting signals of their current location, from which the OnStar® system is able to pinpoint its own location. The navigation antenna receives these GPS signals and provides the data to the VCIM to be processed. The Vehicle Communication Interface Module communicates with the rest of the vehicle over the class 2 serial data bus. Ignition state is determined by the VCIM through class 2 messaging.

The module also has the capability of commanding the horn, door lock/unlock and operating the exterior lamps using the class 2 serial data circuit. When an OnStar® keypress is made, a class 2 message is sent to the audio system to mute all radio functions and transmit OnStar® originated audio. After the audio system is muted, the OnStar® signals are transmitted to the audio system on the cellular telephone voice signal circuit, and returned to the module on the cellular telephone voice low reference circuit. The cellular modem 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.

OnStar® Button Assembly

The OnStar® 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 three buttons and a status LED. The buttons are defined as follows

1. The Answer/End Call button, which is black with a white "dot", allows the user to answer and end calls or initiate the personal calling feature if equipped.
2. The blue OnStar® Call Center button, which displays the OnStar® logo, allows the user to connect to the OnStar® Call Center.
3. The red Emergency button sends a high priority emergency call to the OnStar® Call Center when pressed.

The OnStar® button assembly receives ten volts on the keypad supply voltage circuit. When pressed, each button completes a circuit across a resister allowing a specific voltage to be returned to the VCIM on the keypad signal circuit. Depending upon the voltage range returned, the VCIM is able to identify which button has been pressed.

The OnStar® button assembly status 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. The OnStar® LED is controlled by the VCIM over the keypad red LED signal circuit and the keypad green LED signal circuit.

OnStar® Microphone

The OnStar®, or cellular, microphone can be part of the rear view mirror assembly or, on some vehicle lines, can be a separate, standalone unit. In either case, the microphone is supplied voltage on the cellular microphone signal circuit, while voice data from the user is sent back to the VCIM by means of either a cellular microphone low reference circuit or a drain wire.

Cellular and Navigation Antennas

The cellular antenna is the component that allows the OnStar® system to send and receive data over airwaves by means of cellular technology. This antenna is connected at the base to a coax cable that plugs directly into the Vehicle Communication Interface Module. The navigation antenna is used to collect the constant signals of the orbiting satellites. Within the antenna, is housed a "low noise" amplifier that allows for a more broad and precise reception of this data. Current GPS location is collected by the module every time a keypress is made. The OnStar® Call Center also has the capability of "pinging" the vehicle during an OnStar® call, which commands the module to retrieve the latest GPS location and transmit it to the OnStar® Call Center. A history location of the last recorded position of the vehicle is stored in the module and marked as "aged". In the event the VCP loses or is removed from power, this history location is used by the OnStar® Call Center as a default. Actual GPS location may take up to 10 minutes to register in the event of a loss of power. This 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 upon the amount of darkening and/or metallic particles that are embedded in the film of the tinting material.

OnStar® Reconfiguration Procedure

Within the Vehicle Communication Interface Module are a set of unique numbers that identify the OnStar® customer and the specific vehicle the module resides in. These numbers, the Station Identification Number (STID) and the Electronic Serial Number (ESN) are transmitted over the cellular network when an OnStar® keypress is made and are essential for proper identification and connection to the OnStar® Call Center. In the event the VCIM requires replacement, the OnStar® Reconfiguration procedure must be performed. This procedure allows for the new STID and ESN within the replacement module to overwrite the old numbers and update customer and vehicle information at the OnStar® Call Center. The Reconfiguration process is explained within the Vehicle Communication Interface Module replacement procedure.

OnStar® Cellular, GPS, and Diagnostic Limitations

The proper operation of the OnStar® System is dependent on several elements outside the components integrated into the vehicle. These include the National Cellular Network Infrastructure, the cellular telephone carriers within the network, and the Global Positioning Satellite system.

The cellular operation of the OnStar® system may be inhibited by factors such as the user's range from an analog cellular tower, the state of the cellular carriers' equipment, and the location where the call is placed. Making an OnStar® keypress in areas that lack sufficient cellular coverage or have a temporary equipment failure will result in either the inability of a call to complete with a data transfer or the complete inability to connect to the OnStar® Call Center. The OnStar® system may also experience connection issues if the identification numbers for the module (STID and ESN numbers) are not recognized by the cellular carriers local signal receiving towers. OnStar® cellular connection issues such as these require the assistance of the General Motors Technical Assistance Center OnStar® Group, which coordinate with cellular carriers to resolve connection issues. The satellites that orbit earth providing the OnStar® system with GPS data have nearly no failures associated with them. In the event of a no GPS concern, the failure will likely lie with the inability of the system to gain GPS signals because of its location (i.e. in a parking structure), hardware failure, or being mistaken with an OnStar® call which has reached the Call Center without vehicle data. During diagnostic testing of the OnStar® system, the technician should ensure the vehicle is located in an area that has a clear unobstructed view of the open sky, and preferably, an area where analog, cellular calls have been successfully placed. These areas can be found by successfully making an OnStar® keypress in a known good OnStar® equipped vehicle and confirming success with the OnStar® Call Center advisor. Such places can be used as a permanent reference for future OnStar® testing.

Operation of the Hands Free Cellular Phone

The hands free, personal calling cellular phone feature is an additional option to the OnStar® system. During a hands free call, the microphone and audio system operate the same way as a standard 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 are specific commands 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 Vehicle Communication Interface Module. 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 the caller can say "HELP" and the VCIM will return an audible list of available commands. If the customer concern is not being understood or not being heard by the OnStar® system, the user should place a call to the OnStar® call center to verify proper operation of the microphone. Here is an example of the commands and the OnStar® system responses. A complete list of commands is supplied in the information provided to the customer with the OnStar® system.

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Operation of the OnStar® Speech Recognition Systems

OnStar® Gen F1 users communicate with two speech recognition systems. Speech recognition allows the user to speak to one computer in the vehicle, and one reached over a phone line. The computer tries to understand the user's command, and responds by speaking back, or by taking the appropriate action, e.g. dialing the phone.

1. Personal Calling uses a speech recognition system that resides in the vehicle. When the user presses the dot button, the system states, "Ready", and listens for the user's command. The user can speak commands to control the hands-free phone.
2. Virtual Advisor is a remote speech recognition system that the caller access by making a phone call. The user connects to Virtual Advisor by requesting it during personal calling use. The user is then transferred to the Virtual Advisor server and talks to it via a cellular connection.

The OnStar® speech recognition systems use speech technology that is designed to understand a wide range of American English speakers. Although there is no one "right" way to speak English, the system will work best when users try to modify their pronunciation should they encounter difficulty. Users who do not obtain good results are advised to try the tips and "workarounds" found in this section.

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See also:
• CHECKING AFTERMARKET ACCESSORIES
• TESTING FOR INTERMITTENT AND POOR CONNECTIONS
• FASTENER NOTICE
• DIAGNOSTIC SYSTEM CHECK-CELLULAR COMMUNICATION
• ONSTAR DESCRIPTION AND OPERATION
• SYMPTOMS-CELLULAR COMMUNICATION