Principles of Operation

Information and Entertainment System

Principles of Operation

NOTE: The Smart Junction Box (SJB) is also known as the Generic Electronic Module (GEM).

Audio Control Module (ACM)

The audio system can be operated while the key is in RUN or ACC. The accessory delay feature allows the audio system to be operated for a preset period of time after the key is placed in the OFF position and a front door has not been opened. The ACM sends AC voltage audio signals to the speakers or to the amplifier, depending on vehicle configuration. The ACM can produce its own DTCs, which can be communicated to the scan tool through the Medium Speed Controller Area Network (MS-CAN), or can be retrieved through the ACM self-test by simultaneously pressing presets 3 and 6. The ACM communicates via the MS-CAN.

Navigation System

The navigation module is integrated into the ACM and controls the operation and the interface between the user, the vehicle subsystems, and the external components. The navigation module is on the MS-CAN and can be diagnosed with a scan tool.

The vehicle navigation system guides the user to a pre-entered destination. A navigation map DVD stored in the navigation module sends route calculation data to the ACM. The ACM audibly and visually instructs the user of the maneuvers required to arrive at the destination entered.

In order to calculate the initial vehicle position, the Global Positioning System (GPS) antenna is used to track several available satellites simultaneously. The GPS antenna only receives data and does not communicate with the satellites. A gyroscope, integral to the navigation module, monitors the pitch and yaw of the vehicle created during cornering or turning. Vehicle speed and reverse signals received through the MS-CAN are also used to detect vehicle speed and direction changes.

Noise Suppression Equipment

The radio frequency suppression equipment reduces interference transmitted through the speakers by the engine ignition and electrical systems. When installing any new radio suppression equipment components, make sure that a good contact is made at all connections.

Satellite Audio

The satellite audio system consists of a Satellite Digital Audio Receiver System (SDARS) module, a satellite radio antenna, and an antenna cable. The satellite radio antenna receives digital audio signals and sends them to the SDARS module, where the signals are converted to analog and sent to the ACM, the Rear Entertainment Module (RETM) (if equipped with the DVD entertainment system but not the SYNC system), or the Accessory Protocol Interface Module (APIM) (if equipped with the SYNC system). The SDARS module communicates via the MS-CAN.

Antenna - AM/FM

For sedans, the combination AM/FM antenna is located on the rear window glass. An antenna isolator module is used to reduce interference from the rear window defroster. The audio signals are sent to the ACM via a coaxial cable. The AM/FM antenna cannot be replaced separately from the rear window glass.

For wagons, a fixed-mast AM/FM antenna is used, instead of an in-glass antenna.

Antenna - Satellite Radio

The satellite radio antenna is located on the roof of the vehicle. The antenna receives digital audio signals and sends them to the SDARS module through the satellite radio antenna cable. For sedans, a dedicated satellite radio antenna is used. For wagons, a combination AM/FM/satellite radio antenna is used.

Subwoofer

The Audiophile system is equipped with a subwoofer and subwoofer amplifier. The ACM controls the subwoofer amplifier through the enable/clip detection circuit. The enable/clip detection circuit carries out 2 functions: to turn the amplifier on, and to indicate to the ACM when the subwoofer output distortion signal reaches a damaging level. The ACM then clips the audio output signal to prevent damage to the subwoofer.

DVD Entertainment System

The DVD entertainment system utilizes a RETM, mounted to the headliner, which provides video playback on a screen when a video DVD is played. The audio signals to the rear speakers are routed from the ACM through the RETM. The wake-up signal for the RETM is sent from the ACM through the MS-CAN.

Single-Play Mode

In single-play mode, any audio input routed through the RETM is broadcast through all of the vehicle speakers. These audio inputs include the RETM, satellite audio, SYNC audio, and peripheral gaming devices plugged into the RETM.

Dual-Play Mode

In dual-play mode, the ACM continues to control the output to the front speakers, while the RETM mutes the audio to the rear speakers. The RETM continues to broadcast the rear audio source to the headphones. When the headphones are set to channel A, all audio sources can be accessed. When the headphones are set to channel B, only the DVD audio and auxiliary audio sources (such as a gaming system) can be sent to the headphones.

SYNC System

The SYNC system allows interaction with several types of customer devices, including mobile phones and media devices. The system is comprised of the APIM, a microphone (located in the auto-dimming interior mirror), the Universal Serial Bus (USB) cable and port, and the audio input jack. The APIM contains an on-board Bluetooth chipset, which enables certain wireless devices to interact with the system.

The APIM consists of 2 internal modules: the Consumer Interface Processor (CIP) and the Vehicle Interface Processor (VIP). The modules are not replaceable individually, but can be flashed independently, if required.

The CIP interfaces with all of the inputs to the APIM. The CIP contains an analog-to-digital-to-analog converter, as well as the Bluetooth chipset. Any consumer-available application upgrades that are available are loaded directly to the CIP through the USB port.

The VIP provides an interface between the CIP and the vehicle. The main functions of the VIP are controlling the APIM power management and translating both inbound and outbound signals over the Controller Area Network (CAN).

The APIM can receive inputs from the following audio sources:

- USB port
- Audio input jack
- SDARS module
- Bluetooth

The USB port can be used for connecting a media device (such as an iPod(R)) with the device's available cable, or for directly plugging in a portable mass storage device (such as a "thumb drive"). When playing media files stored on a mass storage device, the SYNC system only plays files that do not have Digital Rights Management (DRM) protection. The USB port can also be used for uploading vehicle application upgrades.

The USB port is powered by the APIM, so no external power source is needed to power a device plugged into the USB port if the device supports this feature.

The audio input jack can be used for connecting a media device (such as an iPod(R)) utilizing a 1/8-inch audio jack. When a device is connected through the audio input jack, only the speaker volume can be controlled by the ACM. All other functions (such as seek, fast forward, pause, etc.) must be carried out on the device itself.

If the vehicle is equipped with satellite audio, the audio signals from the SDARS module are sent to the APIM, rather than directly to the ACM. The APIM then relays the satellite audio signals to the ACM.

The Bluetooth interface can accommodate both Bluetooth-enabled mobile phones and Bluetooth-enabled media devices. Any Bluetooth device used with the SYNC system must first be paired with the system before it is operational.

Bluetooth is a secure, short-range radio frequency that allows devices to communicate wirelessly through radio waves. The operating range of a Bluetooth signal is a maximum of 32 feet.

Only one Bluetooth phone and one Bluetooth media device can be connected to the system at any one time. If an additional device of either type is paired with the system and made active, the APIM disconnects any active connection and establishes a connection with the new device.

It is important to understand that not all mobile phones have the same level of features when interacting with the SYNC system. For a list of compatible phones, refer to the SyncMyRide website .

In addition to audio information, metadata may also be sent to the APIM from a device plugged into the USB port. Metadata consists of such information as artist, album title, song title, and genre. The metadata is used by the APIM to create indexes that can be used to sort for particular music, based on customer preference. Not all USB devices send metadata to the APIM; also, no metadata is transferred when a device is connected through the audio input jack. When a new media device is connected to the SYNC system, the APIM automatically indexes the information. This may take up to several minutes (depending on the amount of data on the device), and is considered normal operation. When a device that was previously connected to the SYNC system is reconnected, the APIM updates the index (rather than creating a new one), which reduces the amount of time needed to create the index.

The APIM receives both stereo and mono sound inputs, and can also transmit both stereo and mono sound. The mono function is used to receive the microphone input, and to send sound to the ACM for voice prompts, the Text-To-Speech (TTS) feature, ringtones, and any audio received through a connected mobile phone. The TTS feature speaks information so that it does not have to be read from the display.

The APIM communicates via the MS-CAN.

Voice Recognition For Vehicles With Navigation And The SYNC System

When the audio system enters voice recognition mode, the ACM initially controls the voice recognition feature. The microphone is wired directly to the APIM, which relays the microphone input to the ACM through dedicated wiring. If the first command spoken is part of the ACM voice recognition set, the ACM retains control of the voice recognition and takes the appropriate action(s). If the first command spoken is part of the APIM voice recognition set, the ACM shuts off its own voice recognition and broadcasts a Controller Area Network (CAN) message to the APIM, transferring the voice recognition to the SYNC system and providing the voice command that was spoken. The ACM controls the voice engine for the base audio, navigation, and climate control systems. The APIM controls the voice engine for the SYNC system (USB port, audio input jack, Bluetooth).

Steering Wheel Controls

The steering wheel controls consist of a series of resistors. Each steering wheel control switch function corresponds with a specific resistance value within the switch. When a switch is pressed, the ACM (or the APIM) monitors the change in reference voltage to determine the requested function.

Audio Input Jack - Vehicles Without The SYNC System

The audio input jack allows for a portable MP3 player to be connected to the vehicle audio system. When a portable MP3 player is connected, audio from the MP3 player can be played through the vehicle speakers.

Audio Signals

Audio signal flow varies greatly depending on vehicle content.

Stereo signals contain left and right channel information, and are used for most audio signals.

A mono signal is used for the microphone input to the APIM. The mono signal is also used for the voice prompts, the TTS feature, ringtones, and any audio received through a connected mobile phone. These audio signals are output from the APIM to the ACM. The mono and stereo outputs from the APIM utilize separate circuits.

A digital signal is used to transmit data from a media device connected through the USB port to the APIM. The APIM then converts the signal to analog and relays the signal to the ACM.

A wireless signal is used to broadcast audio signals from a Bluetooth device to the APIM. As with a digital signal sent through the USB port, the APIM converts the wireless audio signal to analog and relays it to the ACM.

Network Communication

The following audio system components communicate via the MS-CAN:

- ACM
- Navigation ACM
- SDARS module
- RETM
- APIM

There are numerous messages internal to the audio system. The functions of these messages include (but are not limited to):

- Changing the audio source
- Changing equalizer settings
- Updating the ACM display
- Dialing phone numbers from the ACM (if equipped with the SYNC system)

In addition, the following messages are utilized by the audio system in conjunction with systems outside of the audio system:

Audio System: