Cellular System, Entertainment System, and Navigation System: Overview

Circuit/System Description

The radio receives a vehicle speed signal from the electronic brake control module in order to correlate actual vehicle speed to the movement of the vehicle calculated by the navigation system and reported serial data.

The radio communicates with the radio controls via serial data. This DTC indicates a fault in the radio controls. No external circuits are involved. The radio may continue to respond normally to faceplate functions when this DTC is set.

The multi-band antenna is located on the roof of the vehicle. The radio antenna is enabled when the radio is turned on. The radio provides battery voltage to the antenna using the center conductor of the antenna coaxial cable. When a 12 V signal is seen on the center conductor of the antenna coax, both AM and FM signals are amplified.

The digital radio receiver, located inside the radio, receives digital radio information from the digital radio antenna located on the outside of the vehicle. The digital radio receiver is connected to the digital radio antenna via a shielded coax cable. The digital radio antenna contains an amplifier which is powered by the radio through the coax cable.

When the radio is on, a discrete 12 V signal is supplied on the entertainment remote enable circuit to the Audio Amplifier, Color Info Display Module (if equipped), the Seatback Video Displays (if equipped), and the Active noise Cancellation Module (if equipped). This signal is used to control the power state of the components.

When the radio is initially installed in the vehicle, the radio receives VIN information via serial data. The radio stores a portion of the VIN and compares this sequence to the VIN information received each time the radio powers on. The VIN in the radio is a single one-time learn.

The radio theft deterrent system is intended to disable or limit radio functionality if incorrect vehicle information is received by the radio. The radio disables functionality if the VIN information received by the radio does not match the VIN information that has been learned by the radio. This DTC is generated by the module when the Theft Protection is activated.

The radio amplifier control circuit provides varying pulse width modulated (PWM) signals to control overall muting of the amplifier. The PWM signals are varying duty cycle percentages ranging from 0-100 percent. A low duty cycle un-mutes all amplifier channels and a high duty cycle mutes all amplifier channels. The amplifier control circuit will measure less than 1 V when the mute function is OFF, and approximately 8 V DC when at full mute. The radio monitors the amp control circuit for faults.

The radio can command the seatback video display mode on vehicles equipped with rear seat entertainment (RSE) video. The radio utilizes discreet mode control circuits to each display to control the screen display mode via a pulse width modulated signal. If the display screen does not receive a signal, the display screen will operate in a default full screen mode.

The radio can control the seatback video display brightness on vehicles equipped with rear seat entertainment (RSE) video. A single brightness control circuit is used by the radio to control the display screen brightness for both displays via a pulse width modulated signal. If the display screen does not receive a signal, the display screen will operate at default brightness, which is a middle brightness level.

The telematics 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 telematics communication interface control module on the signal circuit. The telematics communication interface control module provides a ground for the cellular phone microphone via the low reference wire.

The navigation antenna is connected to the telematics communication interface control module and the radio through the navigation signal splitter. The navigation signal splitter distributes the navigation signal to both the telematics communication interface control module and the navigation radio. The telematics communication interface control module supplies 5 V through the coax cable to power the internal antenna amplifier through the signal splitter. The radio supplies 5 V through the center conductor of the coax cable to power the splitter.

The cellular phone and navigation antenna is connected to the telematics communication interface control module. This module supplies 5 V to the cellular phone and navigation antenna to power the internal amplifier. When the vehicle is equipped with the optional navigation radio, a navigation signal splitter is installed to distribute the GPS signal to both the telematics communication interface control module and the navigation radio. The navigation radio supplies 5 V through the GPS antenna coaxial cable to the navigation signal splitter to power the internal navigation radio signal amplifier.

The OnStar® button assembly consists of 3 buttons, Call/Answer, OnStar® Call Center, and OnStar® Emergency. The telematics communication interface control module 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 telematics communication interface control module over the keypad signal circuit. Depending upon the voltage range returned, the telematics communication interface control module is able to identify which button has been activated.

The term application refers to any piece of software that works on a system (hardware) that is being operated by it's 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 (1/8 in.) auxiliary audio input jack is located in the console. All circuits from the auxiliary jack are connected directly to the radio. When a device is connected to the auxiliary jack an internal switch opens. The radio detects the device and switches to AUX as the audio source. Audio signals from the device are sent to the radio from the auxiliary input jack via the left, right, and common audio signal circuits.

USB Port

The vehicle may be equipped with a USB port in the console. 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 or multimedia player interface module. 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.

Auxiliary Audio Input Jack

The 3.5 mm (1/8 in.) auxiliary audio input jack is located in the console. When a portable audio playback device is connected to the auxiliary jack, an internal switch opens the detection signal circuit and the radio will switch to AUX as the audio source. The radio detects the device and switches to AUX as the audio source. Audio signals from the device are sent to the radio from the auxiliary input jack via the left, right, and common audio signal circuits.

USB Port and SD Card Reader

The navigation system has a USB port and SD card reader slot located in the center console. The USB port and the card reader slot interface with a hub device, internal to the auxiliary jack, USB, and memory card receptacle assembly. The internal hub device interfaces directly with the radio via a USB cable. The auxiliary jack, USB, and memory card receptacle assembly receives fused battery voltage and ground from the harness to power the internal hub device as well as providing additional amperage to power USB devices.

The internal hub device interfaces directly with the radio via a standard USB cable. A Mini type USB connector is 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.

The USB port allows 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.

Not all portable media player devices or file types are compatible. Refer to the owner's manual for information on USB devices, control, and operation.

SD Card Reader

The navigation system in this vehicle uses an SD Card to store map information. The map database SD card must be inserted in the console SD card reader slot for the navigation system to function. If the map database SD card cannot be accessed, navigation related selections will not be available to the infotainment system. The SD card reader is dedicated for map data only, no other file types are supported.

The Bluetooth ® antenna is internal to the telematics communication interface control module and is used to send and receive signals from a Bluetooth ® enabled cellular phone.

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 owners manual, supplements, and the device manufacturers information for information on devices, control, operation. and pairing instructions.

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.

When voice recognition for the navigation equipped infotainment system is started, voice signals from the cellular phone microphone are passed through the telematics communication interface control module to the radio via the voice recognition audio circuits.

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 telematics communication interface control module transmits signals to the audio system on the audio signal and audio common circuits.

The navigation antenna is connected to the telematics communication interface control module. The module supplies 5 V to the antenna to power the internal amplifier through the center conductor of the antenna coax cable.

When the vehicle is equipped with the optional navigation radio, a navigation signal splitter is installed to distribute the navigation signal to both the telematics communication interface control module and the navigation radio. The telematics communication interface control module supplies 5 V through the coax cable to power the internal antenna amplifier through the signal splitter.

The telematics communication interface control module 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 radio controls and information display are separate components from the radio. Each component is supplied battery voltage and ground. The radio uses the wake up circuit to control the power state of the display. The radio controls communicate with the info display module through the LIN serial data circuit. Display backlighting dimming level, graphical data, and radio control inputs are communicated over the CGI data circuits between the display and the radio.

Communications between the HVAC controls and the HVAC control module are on a separate LIN circuit. The HVAC control module communicates status information to the radio via GMLAN for HVAC information display.

The radio/HVAC controls are supplied battery voltage and ground. The radio controls the power state of the controls via a wake up circuit. Communications between the radio controls and the radio are through the CGI serial data circuits.

The radio info display module is supplied battery voltage and ground. The radio controls the power state of the display through the remote enable circuit, which is also used to control the power state of other infotainment devices. Display backlighting dimming level, and screen touch signal are communicated over the touch data circuits. The radio sends graphical image data to the display via a dedicated video interface cable.

Each of the audio output channel circuits (+) and (-), at the radio and audio amplifier have a DC bias voltage that is approximately one half of 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. 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.

The telematics communication interface control module 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 telematics communication interface control module 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.

USB Port and SD Card Reader

SD Card Reader

USB Port

Not all portable media player devices or file types are compatible. Refer to the owner's manual for information on USB devices, control, and operation.

The infrared remote signal is used to transmit signals from the rear seat entertainment (RSE) remote control via pulse width modulated (PWM) signals to the radio. When a key on the remote is pressed, the remote control sends an infrared message to the infrared receiver located in the DVD display. The infrared receiver converts these infrared signals into a frequency and sends the message to the radio to perform the appropriate function. Both seatback displays contain receivers for the infrared remote, which are connected to common (+) and (-) signal circuits to the radio.

The driver seatback DVD display contains the infrared transmitter for the wireless headphones. The audio that is sent over the DVD audio signal circuits is a varying AC voltage. The transmitter processes the signal and transmits the audio signals to the headphones. If the display is in the closed position, the infrared signals will not be available for the operation of the wireless headphones and the remote control.

The telematics communication interface control module is capable of interpreting voice commands received over the cellular microphone circuit. 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.

OnStar Description and Operation

This OnStar® system consists of the following components

Telematics 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.

Mobile Identification Number and Mobile Directory Number

The telematics 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 work arounds 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 (with Monochrome Display)

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 .

Each item in the list below represents topics covered in detail below.

Radio Circuit Operation
Information Display and Controls
Antenna System
Radio Reception
Speaker Operation
Audio Amplifier (If equipped)
Theft Deterrent
Auxiliary Audio Input Jack (If equipped)
Multimedia Player Interface Module (if equipped)
USB Port (If equipped)
Active Noise Cancellation (If equipped)
OnStar ®
Steering Wheel Controls (If equipped)
Auto Volume Control

Radio Circuit Operation

Radio Power

The radio does not use a discrete ignition feed circuit for power moding. The power mode master provides the system power mode to the radio via serial data messages. The power mode master 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 Audio 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.

Remote Enable Output

The remote enable circuit is a discrete 12 V signal supplied to infotainment system components when the radio is producing audio, needs the front display on, needs video entertainment system components on, or needs to produce chimes. This signal is used to control the power state of the components. There is no output on radio the remote enable circuit when the vehicle is in the CRANK powermode, this is to minimize current consumption from the attached modules and also to avoid audio pops during crank events.

Scheme 14

Scheme 14: Radio/HVAC Communications

Callout	Component Name
1	Radio/HVAC Controls
2	Info Display Module
3	Radio
4	HVAC Control Module
5	Data Link Connector
A	GMLAN
B	Local Interconnect Network-HVAC
C	CAN Graphical Interface
D	Local Interconnect Network-Radio

The radio/HVAC control is a separate component from the radio. The radio/HVAC controls contain the radio control knobs and buttons for all audio functions.

The radio/HVAC controls operate radio functions through serial data messages. The radio/HVAC controls communicate to the info display module through LIN serial data. The info display module communicates to radio through CGI serial data.

When the operator rotates a radio control knob to change radio stations or increase the volume a message is sent to the radio over serial data. After receiving the message the radio will make the adjustment. Messages communicated between the radio and the radio/HVAC controls and info display include the following

Button presses/knob rotations
Info display module dimming
Radio/HVAC controls back-lighting
Graphics and text information

HVAC data for controls and status indicators is communicated between the radio/HVAC controls and the HVAC control module with a separate LIN serial data circuit. HVAC status screen information from the HVAC control module is transmitted to the radio on the GMLAN serial data circuit. The radio then displays the desired screen information on the info display using the video data circuits.

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.

Radio/Audio System Description and Operation (with Color Display)

Each item in the list below represents topics covered in detail below.

Radio Circuit Operation
Information Display and Controls
Antenna System
Radio Reception
Speaker Operation
Audio Amplifier (If equipped)
Theft Deterrent
Bluetooth ® (UP9) (if equipped)
Applications (if equipped)
Auxiliary Audio Input Jack (If equipped)
USB Port (If equipped)
Active Noise Cancellation (If equipped)
Navigation System Components and Features (if equipped)
OnStar ®
Steering Wheel Controls (If equipped)
Auto Volume Control

Radio Power

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 Audio Outputs

Remote Enable Output

Scheme 15

Scheme 15: Information Display and Controls

Callout	Component Name
1	Radio/HVAC Controls
2	Info Display Module
3	Radio
4	HVAC Control Module
5	Data Link Connector
A	GMLAN
B	Local Interconnect Network
C	CAN Graphical Interface
D	Digital Video
E	Touch Screen Serial Data

The info display module has continuous power and ground. When the radio is on, a discrete 12 V signal is supplied on the remote enable circuit to the color display module. This signal is used to control the power state of the module, which is active when the signal is high and inactive when the signal is low.

The info display module receives digital video data from the radio for on-screen display information through a dedicated video cable. The radio communicates with the info display module over the touch screen serial data circuits for touch screen inputs and backlighting dimming level.

The radio/HVAC controls communicate radio control inputs directly to the radio with the CAN Graphical Interface (CGI) data circuits. After receiving the message the radio will perform the requested function. Messages communicated between the radio and the radio/HVAC controls include the following

Button presses/knob rotations
Commands for the state of indicators
Controls back-lighting

HVAC data for controls and status indicators is communicated between the radio/HVAC controls and the HVAC control module on a separate LIN serial data circuit. HVAC status screen information from the HVAC control module is transmitted to the radio on the GMLAN serial data circuit. The radio then displays the desired screen information on the info display using the video data circuits.

Video Entertainment System Description and Operation

Each item in the list below represents topics covered in detail below

Seatback Display Circuit Operation
Seatback Display System Components
Video Screens
Remote Control
Wireless Headphones
Video Inputs Only

Seatback Display Circuit Operation

Seatback Display Power

The Seatback display uses the common radio power enable voltage feed circuit and direct feed for B+ power moding.

Seatback Display Grounds

The vehicle harness provides a ground for the Seatback display system.

Seatback Display Outputs

The Seatback display can only output video to each screen.

Cellular System, Entertainment System, and Navigation System: Overview GMC Terrain I