Cellular Communication System Cadillac Escalade GMT800

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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. 5. 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® vehicle communication interface module (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

Scheme 126

Circuit Description

The vehicle communication interface module (VCIM) detects that the cellular microphone is connected through the cellular microphone signal circuit and the cellular microphone low reference circuit.

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 VCIM detects an open in the cellular microphone low reference 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 VCIM 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 VCIM detects the microphone connected for 5 consecutive 100 millisecond cycles.
2. A history DTC clears after 50 malfunction free ignition cycles.
3. The VCIM 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 VCIM is sending out the proper supply voltage.

Scheme 127

The cellular portion of the cellular and navigation antenna is connected to the vehicle communication interface module with a RG-174 coax cable. The vehicle communication interface module (VCIM) polls the data from the 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 VCIM does not detect the presence of the cellular antenna
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 VCIM detects the presence of the cellular and 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 numbers below refer to the step numbers on the diagnostic table.

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

Scheme 128

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 (VCIM) on the keypad signal circuit. Depending upon the voltage range returned, the VCIM 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 VCIM 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 VCIM 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 VCIM 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 VCIM is sending out the proper supply voltage.

Scheme 129

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 (VCIM) on the keypad signal circuit. Depending upon the voltage range returned, the VCIM 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 pressed or stuck for more than 15 seconds.
2. The above conditions are present for greater than 15 seconds.

1. The VCIM 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 VCIM 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.

Scheme 130

The navigation portion of the cellular and navigation antenna is connected to the vehicle communication interface module (VCIM) with a RG-174 coax cable. The VCIM polls the data from the 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 VCIM 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 VCIM detects the presence of the cellular and navigation antenna.
2. A history DTC clears after 50 malfunction free ignition cycles.
3. The VCIM receives the clear DTC command from the scan tool.

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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.

Diagnostic Aids

1. The diagnostic procedure used for DTC U1500 in OnStar® systems with single module generations of OnStar® differ greatly from previous generations with 2 modules. While these older generations denoted a failure of the 3-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 2-module generation of OnStar® is used should be confirmed. Refer to «ONSTAR DESCRIPTION AND OPERATION»(/cadillac/escalade/gmt800-2001-2006/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.

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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 .

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 pressing the white dot button at the end of 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.

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Symptoms - Cellular Communication

Important: The following steps must be completed before using the symptom tables.

1. Perform the «DIAGNOSTIC SYSTEM CHECK - CELLULAR COMMUNICATION»(/cadillac/escalade/gmt800-2001-2006/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»(/cadillac/escalade/gmt800-2001-2006/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 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»(/cadillac/escalade/gmt800-2001-2006/remont/entertainment-systems/#cellular-communication-system)
2. «UNABLE TO CONTACT ONSTAR CALL CENTER»(/cadillac/escalade/gmt800-2001-2006/remont/entertainment-systems/#cellular-communication-system)
3. «ONSTAR BUTTON LED INOPERATIVE»(/cadillac/escalade/gmt800-2001-2006/remont/entertainment-systems/#cellular-communication-system)
4. «NO (OR NOISY) ONSTAR AUDIO»(/cadillac/escalade/gmt800-2001-2006/remont/entertainment-systems/#cellular-communication-system)
5. «MICROPHONE INOPERATIVE - CALLER CANNOT BE HEARD»(/cadillac/escalade/gmt800-2001-2006/remont/entertainment-systems/#cellular-communication-system)
6. «VOICE RECOGNITION INOPERATIVE»(/cadillac/escalade/gmt800-2001-2006/remont/entertainment-systems/#cellular-communication-system)
7. «ONSTAR STEERING WHEEL CONTROL FUNCTIONS INOPERATIVE»(/cadillac/escalade/gmt800-2001-2006/remont/entertainment-systems/#cellular-communication-system__onstar-steering-wheel-control-functions-inoperative)
8. «GLOBAL POSITIONING SYSTEM (GPS) DATA NOT CURRENT OR INACCURATE»(/cadillac/escalade/gmt800-2001-2006/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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OnStar Steering Wheel Control Functions Inoperative

Some vehicles equipped with the OnStar® system have the capability of accessing voice mailboxes and other automated phone systems by means of the steering wheel controls, while the OnStar® Personal Calling (OPC) feature is in use. If the "Talk" or "Mute" button (depending upon the vehicle) on the steering wheel controls are depressed during an OPC call, the Vehicle Communication Interface Module receives the message on the Class 2 serial data bus from either the radio, driver information module, or body control module. This message is interpreted as a request to turn any spoken numbers into Dual Tone Multi-Frequency (DTMF) tones to be delivered over the airwaves to the phone system the user is communicating with. Complete instructions for operation of these features can be found in the information provided to the customer with the OnStar® system.

The steering wheel controls are a resistor network that consist of multiple momentary contact switches and a series of resistors. The switches and resistor network are arranged so that each switch has a different resistance value. When a switch is pressed, a voltage drop occurs in the resistor network, which produces a specific voltage value unique to the switch selected, to be interpreted by either the radio, dash integration module, or body control module. In the event the OnStar® steering wheel control functions are inoperative, technicians should Refer to DIAGNOSTIC SYSTEM CHECK - ENTERTAINMENT SYSTEM in Entertainment to begin diagnosis of the steering wheel control concern.

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® 3-button assembly has been damaged and the OnStar® 3-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.

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Removal Procedure

1. Remove the I/P trim panel. Refer to TRIM PANEL REPLACEMENT - INSTRUMENT PANEL (I/P) UPPER in Instrument Panel, Gages and Console.
2. Lower the headliner. Refer to HEADLINER REPLACEMENT in Interior Trim.
3. Disconnect the cables from the antenna base. Important: Observe the routing of the cables.
4. Remove the cable retainers from the roof and pillar.
5. Disconnect the cable (3) from the module.

Installation Procedure

1. Install the cable retainers to the roof and pillar.
2. Connect the cables (3) to the module.
3. Connect the cables to the antenna base. Important: Ensure the cables are routed properly and there is no sharp bends in the cables.
4. Install the headliner. Refer to HEADLINER REPLACEMENT in Interior Trim.
5. Install the I/P trim panel. Refer to TRIM PANEL REPLACEMENT - INSTRUMENT PANEL (I/P) UPPER in Instrument Panel, Gages and Console.

1. Lower the headliner. Refer to HEADLINER REPLACEMENT in Interior Trim.
2. Disconnect the cables from the antenna.
3. Loosen the retaining nut until the antenna assembly can be pulled from the top of the roof.

1. Place the antenna assembly on the roof opening.
2. Tighten the retaining nut. NOTE: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems. Tighten Tighten the nut to 6 N.m (53 lb in).
3. Connect the antenna cables.
4. Install the headliner. Refer to HEADLINER REPLACEMENT in Interior Trim.

OnStar Button Assembly Replacement (Pick-Up)

The OnStar button assembly located on the rearview mirror can not be serviced separately from the rearview mirror. Should the button assembly need to be replaced, the entire rearview mirror assembly will need to be replaced. Refer to REARVIEW MIRROR REPLACEMENT in Stationary Windows.

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Important: The vehicle communication interface module (VCIM) has a specific set of unique numbers that tie the module to each vehicle. These numbers, the 10-digit station identification and the 11-digit electronic serial number, are used by the National Cellular Network and OnStar® to identify the specific vehicle. Because these numbers are tied to the vehicle identification number of the vehicle, you must never exchange these parts with those of another vehicle.

1. Remove the Instrument Panel (I/P) upper trim panel. Refer to TRIM PANEL REPLACEMENT - INSTRUMENT PANEL (I/P) UPPER in Instrument Panel, Gages and Console.
2. Fully open the I/P storage compartment.
3. Disconnect the electrical connectors (2) from the Vehicle Communication Interface module (VCIM) (1).
4. Disconnect the coaxial cable (3) from the VCIM.
5. Remove the screws (1, 3) from the passenger side upper I/P support (2).
6. Remove the passenger side upper I/P support (2).
7. Remove the screw (1) retaining the VCIM bracket to the I/P.
8. Remove the retainer from the VCIM bracket.
9. Remove the nuts holding the mounting brackets to the VCIM.
10. Remove the VCIM and bracket assembly from the I/P.
11. Remove the nuts (4) from the VCIM mounting brackets (2).
12. Remove the mounting brackets (2) from the VCIM (1).

1. If replacing the VCIM, record the 10-digit STID number, and the 11-digit ESN number from the labels on the new module.
2. Ensure the nuts (3) are installed on the module mounting brackets (3).
3. Install the mounting brackets (2) to the VCIM (1).
4. Install the nuts (4). NOTE: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems. Tighten Tighten the nuts to 2 N.m (18 lb in).
5. Install the VCIM and bracket assembly to the I/P.
6. Install the push in retainer.
7. Install the VCIM screw (1) to the I/P. Tighten Tighten the screws to 2 N.m (18 lb in).
8. Install the passenger side upper I/P bracket (2).
9. Install the I/P upper bracket screws (3). Tighten Tighten the screws (3) to 2 N.m (18 lb in).
10. Install the I/P upper bracket screws (1). Tighten Tighten the screws (1) to 50 N.m (37 lb ft).
11. Connect the coaxial cable (3) to the VCIM.
12. Connect the electrical connectors (2) to the VCIM.
13. Install the I/P trim panel. Refer to TRIM PANEL REPLACEMENT - INSTRUMENT PANEL (I/P) UPPER in Instrument Panel, Gages and Console. 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.
14. Install the scan tool. Use the special functions menu in order to perform the OnStar® setup procedure for this vehicle.
15. 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.
16. 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.
17. Press the blue OnStar® button to connect to the OnStar® Call Center and perform the following procedure: 17.1. Tell the advisor that this vehicle has received a new VCIM. 17.2. Ask the advisor to add the new STID and the ESN to update the customer's account. 17.3. Follow any additional instructions from the OnStar® advisor. 17.4. Ask the advisor to activate the OnStar® Personal Calling feature, if available.
18. The default language for voice recognition in the generation 5 OnStar® module is English.

1. Remove the overhead console. Refer to CONSOLE REPLACEMENT - OVERHEAD in Interior Trim.
2. Disconnect the microphone (2) connector from the jumper harness.
3. Unclip the microphone bracket (1) from the overhead console.
4. Disconnect the microphone 2-way connector (2) from the mating 2-way connector.

1. Mount the microphone (1) to the overhead console at the left rear corner of the overhead console.
2. Clip the microphone bracket (1) to the overhead console.
3. Connect the microphone connector (2) to the mating 2-way connector.
4. Reinstall the overhead console. Refer to CONSOLE REPLACEMENT - OVERHEAD in Interior Trim.

OnStar Description and Operation

This vehicle uses the Generation 5 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 global positioning system (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 VCIM 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 rearview mirror on some vehicles or a separate unit on others. The button assembly is comprised of 3 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 Emergency button, which will display either a red or white cross, sends a high priority emergency call to the OnStar® call center when pressed.

The OnStar® button assembly receives 10 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® status LED is located to the right of the emergency button on a mirror-mounted assembly and to the left of the answer/end call button when the assembly is mounted on the dash or overhead console. 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® system is still able to make a call, the LED will flash red during the call. 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 rearview mirror assembly, or on some vehicle lines, can be a separate, stand alone 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

This vehicle will be equipped with either separate cellular and navigation antennas, or a combination cellular and navigation antenna, which brings the functions of both into a single part.

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 VCIM. 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.

Deactivated OnStar® Accounts

In the event a customer has not renewed their OnStar® account after expiration or the account was never activated, OnStar® will make a discrete cellular call to the vehicle to deactivate the OnStar® system. Before taking this action, customers are notified that the OnStar® system in their vehicle will be deactivated unless they elect to renew the account. After the vehicle has been successfully deactivated, customers will experience the following when attempting to contact OnStar from their vehicle

1. During an OnStar® Call Center button press, the customer will be connected to a dedicated sales team who can sell an OnStar® subscription and reactivate the vehicle. Depending on the type of OnStar® hardware in the vehicle, the customer may first hear a demonstration message stating there is no current OnStar® subscription for the vehicle, and directing the customer what to do to activate services.
2. During an Emergency button press, a demo message will be played indicating the service has been deactivated.
3. OnStar® Personal Calling (OPC) will not be available, as this feature requires the customer to have a current OnStar® account. Attempts to use this feature may result in cellular connection failure messages and the inability to connect to the number dialed.

It is of particular note, that when an OnStar® system is successfully deactivated, it will NOT attempt to connect to the OnStar® Call Center in the event of a collision or if the vehicle's front airbags deploy for any other reason.

Certain vehicles that have never had an active OnStar® account, that have been deactivated, may be unable to establish a connection with the OnStar® Call Center. When normal published diagnostic procedures do not indicate a possible cause for the no connect concern, the vehicle may have been deactivated. For deactivated vehicles, a no connect response should be considered normal operation. Further diagnosis and subsequent repair is only necessary should the customer elect to become an active OnStar® subscriber.

OnStar® Reconfiguration Procedure

Within the VCIM 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, or the OnStar® Reconfiguration Procedure found in the Cellular Communication diagnostic information and procedures section.

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 GPS 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 coordinates with cellular carriers to resolve connection issues.

The satellites that orbit earth providing the OnStar system with GPS data have almost 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.

OnStar® Personal Calling

The hand free, OnStar® Personal Calling (OPC) cellular phone feature is an additional option to the OnStar® system. This feature is already embedded within the VCIM, however, it must be activated by an OnStar® advisor. This is done most often during the initial OnStar® configuration, if the home location of the vehicle is in a geographic area where OnStar® Personal Calling is available. In the event this feature is not enabled, customers may connect to the OnStar® Call Center by pressing the blue OnStar® button, and asking an advisor if OPC is available in their area. Users of the Generation 5 OnStar® system can verify the system has been configured for OnStar® Personal Calling by pressing the answer/end call button, waiting for the system to respond "OnStar Ready" then speaking "dial". If the system responds "phone unavailable" the system has not been configured for OPC. All other responses confirm that OPC has been enabled.

Operation of the Hands Free Cellular Phone

OPC operates similar to most hand held cellular phones in that the availability for its usage is based on minutes or "units". The customer must have a current OnStar® subscription, as this feature cannot be utilized without it. To use OnStar® Personal Calling, the customer must also purchase units as outlined in the owners guide provided with the OnStar® system. When the customer purchases minutes, an OnStar® advisor "loads" these minutes into the VCIM over the airwaves at the time of the request, or through a discrete cellular call to the vehicle at a later time. Once loaded into the module, the units may be used for non-international, outbound cellular phone calls and connection with the OnStar® Virtual Advisor. Units begin to deplete (one unit is equal to one minute) as the customer makes outbound phone calls, answers inbound phone calls, or while connected to the OnStar® Virtual Advisor. In addition, units also have an expiration date, depending upon the type of units purchased. This date is established when the download is performed and any remaining units expire when the date within the VCIM (which is based on current date and time transmitted by GPS satellites) has passed. At any time, the user can press the answer/end call button, say "Units" and verify the number of units remaining.

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 "OnStar 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.

The Vehicle Communication Interface Module interprets all of the voice-activated commands. A complete 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. Following this description 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.

OnStar® Steering Wheel Controls

Some vehicles equipped with the OnStar® system have the capability of accessing voice mailboxes and other automated phone systems by means of the steering wheel controls, while the OnStar Personal Calling (OPC) feature is in use. If the "Talk" or "Mute" button (depending upon the vehicle) on the steering wheel controls are depressed during an OPC call, the Vehicle Communication Interface Module receives the message on the Class 2 serial data bus from either the radio, driver information module, or body control module. This message is interpreted as a request to turn any spoken numbers into Dual Tone Multi-Frequency (DTMF) tones to be delivered over the airwaves to the phone system the user is communicating with. Complete instructions for operation of these features can be found in the information provided to the customer with the OnStar® system.

The steering wheel controls are a resistor network that consist of multiple momentary contact switches and a series of resistors. The switches and resistor network are arranged so that each switch has a different resistance value. When a switch is pressed, a voltage drop occurs in the resistor network, which produces a specific voltage value unique to the switch selected, to be interpreted by either the radio, driver information module, or body control module.

OPC Features

The following is an abbreviated list of features that may have an impact for the technician when servicing or diagnosing an OnStar® system. For a full list of OnStar® Personal Calling features, consult the owners guide provided to the customer with the OnStar® system.

Voice Feedback

The OPC system has the capability of responding to the user with either an automated voice response or with a tone or "beep". These two types of responses can be switched back and forth by pressing the answer/end call button, waiting for the system to respond "OnStar Ready" and speaking the phrase "voice feedback". The system will then respond, "voice feedback is now on/off".

OPC Security/System Lock

Customers have the capability to lock their OPC system by pressing the answer/end call button, speaking "security" and entering a four-digit code. Once this process is complete, the user must enter the code before OnStar® Personal Calling is available. In the event the customer cannot remember their code and is unable to use their system, they can press the blue OnStar button and speak to an advisor to unlock the system by means of a discrete cellular call to the vehicle.

Nametags

Customers have the ability to store telephone numbers within the module, referenced by a "nametag" for the convenience of frequently dialed numbers. This process is initiated by pressing the answer/end call button, waiting for the system response, then speaking the response "store". The system will respond with "number please" at which time the user should enter the number desired to be stored. Once complete, saying the word "store" again lets the system know you are finished entering the number. At this time, the system will elicit the user to assign a "nametag" to that number. From this point forward, the user can dial this number by initiating the OPC feature, speaking the word "call", and repeating the nametag assigned. To delete a nametag, the user should initiate OPC, say "delete" then speak the nametag to be removed. In the event a nametag cannot be deleted in spite of repeated attempts from several speakers, the OnStar® module will require replacement.

Mobile Identification Number and Mobile Directory Number

The Generation 5 VCIM utilizes two numbers for cellular device identification, call routing and connection, a MIN (Mobile Identification Number) and a MDN (Mobile Directory Number). The MIN represents the number used by the cellular carrier for call routing purposes while the MDN represents the number dialed to reach the cellular devise. Although technicians have the capability to change these numbers by means of the scan tool, this should ONLY be done at the direction of and with explicit instruction from the General Motors Technical Assistance Center (GM TAC).

Scheme 143

Operation of the OnStar® Speech Recognition Systems

OnStar® Generation 5 users communicate with 2 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.

Scheme 144

Scheme 145

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See also:
• DIAGNOSTIC SYSTEM CHECK - CELLULAR COMMUNICATION
• ONSTAR DESCRIPTION AND OPERATION
• SYMPTOMS - CELLULAR COMMUNICATION
• ONSTAR STEERING WHEEL CONTROL FUNCTIONS INOPERATIVE