Circuit/System Description
The radio receives a vehicle speed signal from the electronic brake control module (EBCM) in order to correlate actual vehicle speed to the movement of the vehicle calculated by the navigation system and reported serial data.
Each of the audio output channel circuits (+) and (-), at the radio and audio amplifier (if equipped) have a DC bias voltage that is one half of the battery voltage. When using a DMM, each of the audio output channel circuits will measure approximately 6.5 V DC. The audio being played on the system is produced by a varying AC voltage that is centered around the DC bias voltage on the same circuit. The AC voltage is what causes the speaker cone to move and produce sound. This voltage will vary depending on what type of audio is being listened to, talk or music and type of music, as well as the volume setting of the system. Low volume and talk settings will measure around 1V AC and less, where constant music may measure 3 V AC and slightly higher. In an amplified audio system, these similar AC voltage measurements may be slightly higher on the output of the amplifier and the typical AC voltage readings at the output of the radio are less than 1V AC.
Certain devices in the entertainment system must be programmed with specific software and other information to operate correctly. This DTC is the result of an unsuccessful USB programming event of the device. The symptom byte information is for engineering reference only. No external circuit diagnosis is involved
The digital radio receiver (DRR) receives an XM satellite radio signal via the digital radio antenna. This signal is passed to the DRR through the digital radio antenna coax. The DRR sends a varying AC mV signal through separate left and right audio circuits (+ and -) to the radio. The voltage amount and rate of change is dependent upon the type of signal being received. The radio then processes these signals and passes the audio to the appropriate speakers or amplifier.
The radio provides a remote amplifier mute output circuit to control overall muting of the remote amplifier. The amplifier receives pulse width modulated (PWM) signals on the control circuit at varying duty cycle percentages for controlling muted and unmuted functions of the amplifier. Circuitry internal to the radio monitors the remote amplifier mute circuit for faults and sets the appropriate DTC when faults are detected.
The radio can control the video display mode on vehicles equipped with rear seat entertainment (RSE) video. The radio varies a pulse with modulated (PWM) signal to the rear entertainment video screen to command the display mode.
The radio can control the video display brightness on vehicles equipped with rear seat entertainment (RSE) video. The radio varies a pulse with modulated (PWM) signal to the rear entertainment video screen to command the screen brightness to the desired level.
The infrared module is supplied with 10.5 volts from the rear audio/HVAC module when the rear audio system is active. The infrared module is permanently grounded at G300.
The vehicle communication interface control module provides the cellular phone microphone with a supplied voltage on the cellular phone microphone signal circuit. When the microphone is in use, voice data from the user is sent back to the vehicle communication interface control module on the signal circuit. The vehicle communication interface control module provides a ground for the cellular phone microphone via the low reference wire.
The vehicle communications interface module (VCIM) receives information from the radio antenna located on the outside of the vehicle. The radio antenna is connected to the telematics communication interface control module via a shielded coaxial cable. The antenna cable also provides a path for DC current for powering the radio antenna.
The radio antenna is connected to the vehicle communication interface module (VCIM) with a RG-58 coax cable. The VCIM polls the data from the radio antenna once every second.
The OnStar® button assembly consists of 3 buttons, Call/Answer, OnStar® Call Center and OnStar® Emergency. The communication interface module (CIM) supplies the OnStar® button assembly with 10 V via the keypad supply voltage circuit. Each of the buttons, when pressed, completes the circuit across a resistor allowing a specific voltage to be returned to the CIM over the keypad signal circuit. Depending upon the voltage range returned, the CIM is able to identify which button has been activated.
Bluetooth® wireless technology is a short-range communications technology intended to replace the cables connecting portable and/or fixed devices while maintaining high levels of security. The operating range of the signal is approximately 30 feet.
The Bluetooth® antenna is a small fixed antenna connected directly to the telematics communication interface control module and is used to send and receive signals from a Bluetooth® enabled cellular phone.
The term application refers to any piece of software that works on a system (hardware) that is being operated by its own software. Applications are typically small software programs which uses the hardware to perform a specific task, as opposed to operating the entire system.
The audio/video adaptor allows the connection of audio and video signals from an external device such as a camcorder, video game console or MP3 player to the rear seat entertainment system. The middle jack is for left audio (white), the right jack is for right audio (red) and the left jack is for video (yellow). The system requires standard RCA cables to connect your external device to the RCA jacks. The auxiliary audio and video circuits are connected to the radio.
Auxiliary Audio Input Jack
The 3.5 mm auxiliary audio input jack is located in either the instrument panel or the instrument panel center compartment. All circuits from the auxiliary jack are connected directly to the radio. Audio signals from the device are sent to the radio from the auxiliary input jack via the left, right and common audio signal circuits.
The infotainment system may also have an additional auxiliary audio input jack available on the radio face. This input interfaces internally with the radio, no external circuits are involved.
When a portable audio playback device is connected to an auxiliary jack, an internal switch detects the connection and the radio will switch to AUX as the audio source.
USB Port
The vehicle may be equipped with a USB port located in either the instrument panel or the instrument panel center compartment. This port allows USB connectivity to the infotainment system from portable media players or a USB storage device (memory stick/flash drive). When a device is connected to the USB port, the system detects the device and switches to USB as the audio source. Once connected, the device can be controlled from the radio controls.
The USB port is connected to the radio via a standard USB cable. Mini type USB connectors are used to connect the cable at the USB port and at the radio. Standard USB male to female connections are typically used for connecting USB cables together where an in-line connection is required. An in-line cable connection is typically found between the console and I/P harness.
Not all portable media player devices are compatible. Refer to the owner's manual for information on USB devices, control and operation.
The Bluetooth® antenna is internal to or is a small fixed antenna connected directly to, the telematics communication interface control module and is used to send and receive signals from a Bluetooth® enabled cellular phone. The antenna utilizes no cabling and is not external to the vehicle.
In order to use hands-free calling, the cellular phone must be paired to the vehicle. Up to five devices can be paired to the vehicle at one time, but only one can be connected at any given time. To pair a phone, the customer must know how to operate the Bluetooth® functionality of their phone. The pairing process must only be done one time for each phone, unless that phone's information is deleted. For safety reasons, the pairing process is disabled while the vehicle is moving.
Bluetooth® wireless technology is a short-range communications technology intended to replace the cables connecting portable and/or fixed devices while maintaining high levels of security. The operating range of the signal is approximately 30 feet.
The available features and functions are determined by the type of device and the software within the devices being used. For a feature or function to operate, it must be supported in both devices.
The Bluetooth® hardware is internal to the radio. The radio supports streaming of data (music, voice, information) from cellular phones and other mobile devices that support those features. The radio may also be capable of interfacing with cellular phones for hands-free features.
Refer to the vehicle owner's manual, supplements and the device manufacturers information for information on devices, control, operation. and pairing instructions.
The digital radio receiver (DRR) receives an XM satellite radio signal via the digital radio antenna. This signal is passed to the DRR through the digital radio antenna coax. The DRR sends a varying AC mV signal through separate left and right audio circuits (+ and -) to the radio. The voltage amount and rate of change is dependent upon the type of signal being received. The radio then processes these signals and passes the audio to the appropriate speakers or amplifier.
The vehicle communication interface module (VCIM) receives information from a specific radio antenna located on the outside of the vehicle. The radio antenna is connected to the vehicle communication interface module via a shielded coaxial cable. The antenna cable also provides a path for DC current for powering the antenna.
The telematics communication interface control module provides the cellular phone microphone with a supplied voltage on the cellular phone microphone signal circuit. When the cellular phone microphone is in use, voice data from the user is sent back to the telematics communication interface control module on the signal circuit. The telematics communication interface control module provides a ground for the microphone via the low reference wire.
The vehicle navigation radio provides verbal directions to the driver through the radio speakers, The navigation radio receives an audio voice signal from the communication interface module (CIM).
The vehicle navigation radio and OnStar® system both utilize the cellular microphone to receive voice commands. The navigation radio receives an audio voice signal from the vehicle communication interface module (VCIM).
When an OnStar® keypress is made, a serial data message is sent to the audio system to mute all radio functions and output OnStar® originated audio. After the audio system is muted, the vehicle communication interface control module transmits signals to the audio system on the audio signal and audio common circuits.
The communication interface module (CIM) has the capability of commanding the horn, initiating door lock/unlock or operating the exterior lamps using the serial data circuits. These functions are commanded by the OnStar® Call Center per a customer request.
The OnStar® button assembly consists of 3 buttons, Call/Answer, OnStar® Call Center and OnStar® Emergency. The communication interface module (CIM) supplies the OnStar® button assembly with 10 V via the keypad supply voltage circuit. Each of the buttons, when pressed, completes the circuit across a resistor allowing a specific voltage to be returned to the CIM over the keypad signal circuit. Depending upon the voltage range returned, the CIM is able to identify which button has been activated.
AM and FM radio reception is dependent on the following components
- Radio antenna
- Coax cable between the radio antenna and the radio
- Radio
The multi-band antenna is located on the roof of the vehicle. A switched B+ output from the radio entertainment remote enable circuit is used to power the AM/FM portion of this antenna. The antenna enable circuit is also used to control the power state of the amplifier (if equipped) and the rear seat entertainment video display (if equipped).
Each of the audio output channel circuits (+) and (-), at the radio and audio amplifier have a DC bias voltage that is one half of the battery voltage. When using a DMM, each of the audio output channel circuits will measure approximately 6.5 V DC. The audio being played on the system is produced by a varying AC voltage that is centered around the DC bias voltage on the same circuit. The AC voltage is what causes the speaker cone to move and produce sound. This voltage will vary depending on what type of audio is being listened to, talk or music and type of music, as well as the volume setting of the system. Low volume and talk settings will measure around 1 V AC and less, where constant music may measure 3 V AC and slightly higher. In an amplified audio system, these similar AC voltage measurements may be slightly higher on the output of the amplifier and the typical AC voltage readings at the output of the radio are less than 1V AC.
The vehicle communication interface module (VCIM) is a cellular device that allows the user to communicate data and voice signals over the national cellular network. When an OnStar® keypress is made, the VCIM activates and connects the system to the cellular carriers communication system by interacting with the national cellular infrastructure. The module sends and receives all cellular communications over the cellular phone and navigation antenna and cellular antenna coax.
The CIM is capable of interpreting voice commands received over the cellular microphone circuits. Speech recognition allows the user to speak to one computer in the vehicle and one reached over the cellular communication network. The module attempts to understand the users command and responds by speaking back or by taking the appropriate action, e.g. dialing the phone.
Each item in the list below represents topics covered in detail below.
- Audio System Description
- Navigation System Components
- Navigation Radio
- Global Positioning System (GPS) Antenna
- Route Guidance
- Auxiliary RCA Video Jacks (If Equipped)
- Voice Recognition
- Points of Interest
Audio System Description
The Navigation radio operates similar to a traditional radio. For information on the audio description and operation, refer to Radio/Audio System Description and Operation .
OnStar Description and Operation
This OnStar® system consists of the following components
- Vehicle Communication interface Module
- OnStar® button assembly
- Microphone
- Cellular antenna
- Navigation antenna
- Bluetooth® antenna (If Equipped)
- Back Up Battery (If Equipped)
This system also interfaces with the factory installed vehicle audio system.
Scheme 15
| Callout | Component Name |
|---|---|
| HW | Hard-Wired |
| HW | Hard-Wired |
| HW | Hard-Wired |
| HW | Hard-Wired |
| HW | Hard-Wired |
| DB | Serial Data - GMLAN Low Speed |
| DD | Serial Data - GMLAN High Speed |
| B24 | B24 Cellular Phone Microphone |
| C3 | C3 Telematics Communication Interface Control Module Battery |
| S51 | S51 Telematics Button Assembly |
| T4G | T4G Cellular Phone, Navigation and Digital Radio Antenna |
| T4S | T4S Wireless Communication Antenna - Bluetooth |
| K73 | K73 Telematics Communication Interface Control Module |
| A11 | A11 Radio |
| X84 | X84 Data Link Connector |
Mobile Identification Number and Mobile Directory Number
The vehicle communication interface module utilizes 2 numbers for cellular device identification, call routing and connection, a mobile identification number and a mobile directory number. The mobile identification number represents the number used by the cellular carrier for call routing purposes while the mobile directory number represents the number dialed to reach the cellular device.
Operation of the OnStar® Speech Recognition Systems
OnStar® 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 users command and responds by speaking back or by taking the appropriate action, e.g. dialing the phone.
- Personal Calling uses a speech recognition system that resides in the vehicle. When the user presses the phone button, the system states, Ready and listens for the user command. The user can speak commands to control the hands-free phone.
- Virtual advisor is a remote speech recognition system that the caller can 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.
| Concern | Tip for Better Result |
|---|---|
| Noise | Noise may confuse the speech recognition system. You usually get better performance from the system in quieter conditions: The HVAC fan creates noise. Turn it down or OFF for better speech system performance. Driving at high speeds creates louder engine noise and wind noise. You may get better results at lower speeds. An open window or an open sunroof allows more noise to enter the vehicle. Close all windows for better results. Noisy rainstorms can also reduce performance. If passengers are talking while you use the speech system, it may be confused by their speech. You will get better results if all occupants of the vehicle are quiet while the system is listening for commands. |
| When to Speak | In Personal Calling, the system is only listening after it prompts you to speak. When the system prompts you to speak, you have about 5 seconds to respond. If the system does not hear a response, it will prompt you again or cancel the transaction. If you begin to speak too soon, it will tell you "Slower, please." Try pausing for a half second before speaking. In the Virtual Advisor, the system is always listening for commands, even while it is speaking. |
| How to Speak | Speak forcefully and clearly. The noisier the environment, the louder you need to speak. If you are in the driver seat, speak facing the front of the car. If you are a passenger, speak facing the rearview mirror. Speak calmly and naturally. The system may sometimes fail your repeated attempts to give a command. If your speech is distorted by shouting or frustration, this may cause more errors. People with high-pitched voices may have better results by speaking in a deeper, lower-pitched voice. However, do not lower the volume of the voice. Avoid speaking with a rising intonation, like asking a question. Use a flat or falling intonation, like giving an answer. |
| What to Say | Personal Calling: One-word commands The Personal Calling system listens for only one word at a time. There are some exceptions, 2-word phrases that are spoken and understood as a single word, e.g. "virtual advisor", "voice feedback" and "my number". You can enter phone numbers only one digit at a time and the system repeats each digit as it hears it. Say "Help" at the Ready prompt to hear the list of Personal Calling commands. Virtual Advisor can understand sentences with more than one word. It also expects to hear a 4-digit number all at once when it asks for your PIN. Say, "What are my choices?" to hear a list of commands that the Virtual Advisor understands. |
| Entering a phone number | If you have trouble getting numbers correctly into the system, store your frequently-called number in the directory, so the system will remember them. After you have stored a number with a nametag, then you simply say "call" and the nametag in order to call the number. If the system cannot understand your numbers, ask another person to help you enter your frequently-called numbers. This person can speak the numbers, then you can speak the nametag. |
| Storing or dialing a number | When you have finished speaking your phone number, you do not need to say "store" or "dial" to indicate that you are done. If you pause and say nothing, the system will ask you if you want to store or dial. Say "yes". |
| Creating nametags | Short nametags that are similar may be easily confused by the system. You may get better recognition of your nametags if you make them longer, for example "George Washington" without pause, instead of "George" only. If you want to use nametags while driving, it is best to store the nametag with some vehicle noise in the background. If you are in park while you are storing nametags, you can turn the fan on low or open windows in order to create some background noise. |
| Virtual Advisor 4-digit PIN | Say the 4 digits in a natural way, without pausing between digits. |
| Interrupting | When the Virtual Advisor is speaking, you can interrupt it with another command. The first word in your command helps to get its attention. If the Virtual Advisor has trouble understanding your commands when you interrupt, try speaking the first word loudly and clearly, then pause for an instant, then continue with the rest of the command. For example: "Get... my weather" or "Lookup... a quote for General Motors". |
General Tips for Better Speech Recognition
Radio/Audio System Description and Operation
The entertainment system on this vehicle may have several different configurations available to it. To determine the specific configuration of the vehicle, please see the Service Parts ID Label and refer to RPO Code List .
The entertainment system on this vehicle is configured with either a base or an uplevel system. The base and uplevel systems each contain a radio, antenna, speakers and on some systems an audio amplifier. The uplevel system differs from the base system by providing the customer with enhanced audio system features. Some of those features may include the radio data system (RDS), an audio amplifier, programmable equalizer (EQ) and digital satellite radio (U2K).
Each item in the list below represents topics covered in detail below.
- Radio Circuit Operation
- Antenna System
- AM/FM Reception
- Digital Radio Receiver
- Speaker Operation
- Audio Amplifier
- Radio Data System (RDS)
- Integral Multi Disc CD Changer (IMDX)
- Rear Seat Audio (RSA)
- Rear Seat Entertainment (RSE)
- Theft Deterrent
- OnStar®
- Steering Wheel Controls
- Auxiliary Input Jack
- USB Port (If equipped)
- Speed Compensated Volume (SCV)
Radio Circuit Operation
Radio Power
The radio is supplied power by a fused B+ circuit. The radio does not use a discrete ignition feed circuit for power moding. The power mode master (PMM) provides the system power mode to the radio via serial data messages. The PMM determines the system power mode by processing power mode information from ignition switch inputs. Serial data power modes supported by the radio are OFF, ACCESSORY, RUN and CRANK REQUEST.
Radio Grounds
The vehicle harness provides a ground for the radio circuits. The radio may also be case grounded.
Radio Data Link Communication
The radio communicates with other modules via serial data.
Radio Outputs
Each of the audio output channel circuits (+) and (-), at the radio have a DC bias voltage that is approximately one half of battery voltage. The audio being played on the system is produced by a varying AC voltage that is centered around the DC bias voltage on the same circuit. The AC voltage is what causes the speaker cone to move and produce sound. The frequency (Hz) of the AC voltage signal is directly related to the frequency of the input (audio source playing) to the audio system. Both the DC bias voltage and the AC voltage signals are needed for the audio system to properly produce sound.
Radio Head Dimming
Dimming and backlighting levels are determined by the serial data messages the radio receives.
Speaker Operation
Speakers turn electrical energy into mechanical energy to move air, using a permanent magnet and an electromagnet. The electromagnet is energized when the radio or amplifier (if equipped) delivers current to the voice coil on the speaker. The voice coil will form a north and south pole that will cause the voice coil and the speaker cone to move in relation to the permanent magnet. The current delivered to the speaker is rapidly changing alternating current (A/C). This causes the speaker cone to move in two directions producing sound.
Video Entertainment System Description and Operation (Non-Headrest DVD Systems)
Each item in the list below represents topics covered in detail below.
- Rear Seat Entertainment Circuit Operation
- Rear Entertainment System Components
- DVD Player
- Playing a Disc
- DVD Messages
- Parental Control
- Video Screen
- Remote Control
- Wireless Headphones
- Stereo RCA Jacks
- Rear Seat Audio (RSA)
- Audio Outputs
- Wired Headphone Jacks
Rear Seat Entertainment Circuit Operation
RSE Power
The rear seat entertainment (RSE) uses a switched battery voltage feed circuit for power moding. The radio outputs power to this circuit via the entertainment remote enable signal circuit.
RSE Grounds
The vehicle harness provides a ground for the RSE circuits.
RSE Data Link Communication
The RSE does not communicate with serial data.
RSE Outputs
At minimum volume, the plus (+) and minus (-) audio signals are approximately half battery voltage, measured to vehicle ground. These audio signals are sent from the radio to the Infrared Module, most systems have a common minus (-) signal.
Video Entertainment System Description and Operation (Dual Headrest DVD Systems)
Each item in the list below represents topics covered in detail below.
- Dual Headrest DVD Circuit Operation
- Dual Headrest DVD System Components
- Dual Headrest DVD Player
- Playing a Disc
- DVD Messages
- Parental Control
- Video Screen
- Remote Control
- Wireless Headphones
- AUX Inputs
- Audio Outputs
- Wired Headphone Jacks
Dual Headrest DVD Circuit Operation
Dual Headrest DVD Power
The Dual Headrest DVD uses a switched battery voltage feed circuit for power moding.
Dual Headrest DVD Grounds
The vehicle harness provides a ground for the Dual Headrest DVD system.
Dual Headrest DVD Data Link Communication
The Dual Headrest DVD system does not communicate with serial data.
Dual Headrest DVD Outputs
The Dual Headrest DVD system can only output video to each screen and through the AV output for external devices such as a camcorder.