Cellular Communication System: Overview Chevrolet TrailBlazer I

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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The number(s) below refer to the step number(s) 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 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.

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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 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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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 .

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 Remote Radio Audio Output (-) circuit is shorted to voltage the Vehicle Communication Interface Module has been damaged and requires replacement.

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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.

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. The following 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® Generation 5 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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