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 Control Module (ACM) can be operated with the ignition in RUN or ACC. The accessory delay feature allows the audio system to be operated for a preset period of time after the ignition is turned to OFF and a front door has not been opened. The ACM (Audio Control Module) sends AC voltage audio signals to the amplifier(s). The ACM (Audio Control Module) can produce its own DTCs, which can be communicated to the scan tool through the Medium Speed Controller Area Network (MS-CAN).

Front Controls Interface Module (FCIM)

The Front Controls Interface Module (FCIM) acts as a customer interface with the audio system and the climate control system. All of the switches on the panel are part of the FCIM (Front Controls Interface Module), so it is necessary for the module to broadcast messages over the MS-CAN (Medium Speed Controller Area Network) when any switch (audio, climate control, etc.) is pressed. When a climate control switch is pressed, the HVAC module broadcasts a message back to the FCIM (Front Controls Interface Module) to illuminate the correct switches to indicate the status of the climate control.

Front Display Interface Module (FDIM)

The Front Display Interface Module (FDIM) is hardwired to the ACM (Audio Control Module). When the touchscreen is pressed, a signal is sent to the ACM (Audio Control Module), which acts on the signal either by changing the audio setting or by broadcasting a message via the MS-CAN (Medium Speed Controller Area Network) to the module controlling the function that was selected. The audio system, navigation (if equipped), and climate control video feed to the FDIM (Front Display Interface Module) is provided by the ACM (Audio Control Module). If equipped with a rear view camera, the video feed for the camera is provided directly to the FDIM (Front Display Interface Module) by the rear view camera.

Satellite Radio

The satellite radio antenna receives digital audio signals and sends them to the ACM (Audio Control Module) through the satellite radio antenna cables.

Jukebox Feature

The ACM (Audio Control Module) contains a 10 Gigabyte on-board hard drive that is capable of storing music ripped (recorded) from a music disc. The music can be loaded into the jukebox by inserting a disc (in the proper format) and following the on-screen instructions to load the music into the ACM (Audio Control Module). The jukebox cannot rip MP3 discs.

Premium Sound

Audio signals are sent from the ACM (Audio Control Module) to the audio amplifier and to the subwoofer amplifier, which process the audio signals and send them to all of the speakers. An enable/clip detection circuit is utilized for both amplifiers. The circuit carries out 2 functions: to turn the amplifier on, and to indicate to the ACM (Audio Control Module) when the speaker output distortion signal reaches a damaging level. The ACM (Audio Control Module) then clips the audio output signal to prevent damage to the speakers.

THX(R) Sound

The THX sound system provides optimal quality sound in the vehicle. Audio signals are sent from the ACM (Audio Control Module) to the audio Digital Signal Processing (DSP) module, which processes the audio signals and send them to all of the speakers. The audio DSP (Digital Signal Processing) module uses internal software to produce an optimal sound environment. An enable circuit is utilized to enable and mute the audio DSP (Digital Signal Processing) module. The audio DSP (Digital Signal Processing) module communicates on the MS-CAN (Medium Speed Controller Area Network). Customer preference settings such as fade and balance are broadcast to the audio DSP (Digital Signal Processing) module by the ACM (Audio Control Module).

Navigation System

The vehicle navigation system guides the user to a pre-entered destination. No navigation map DVD is needed, as the map guidance information is stored in the ACM (Audio Control Module). The ACM (Audio Control Module) calculates route information based on Global Positioning System (GPS) data. The GPS (Global Positioning System) antenna tracks several satellites simultaneously. The ACM (Audio Control Module) also uses vehicle speed and transmission gear selected messages received through the MS-CAN (Medium Speed Controller Area Network) to detect vehicle speed and direction, resulting in more accurate navigation tracking.

The navigation display is shown on the FDIM (Front Display Interface Module). Either the FDIM (Front Display Interface Module) touchscreen or the buttons on the FCIM (Front Controls Interface Module) can be used to interact with the navigation system.

The compass heading is derived from the GPS (Global Positioning System) antenna signal. There are no serviceable parts for the compass.

A voice recognition system allows the user to interface with the system without using the touchscreen. The microphone provides a direct input to the ACM (Audio Control Module). The microphone is shared with the SYNC system.

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 Accessory Protocol Interface Module (APIM), a microphone, the Universal Serial Bus (USB) cable and port, and the audio input jack. The APIM (Accessory Protocol Interface Module) contains an on-board Bluetooth chipset, which enables certain wireless devices to interact with the system.

The APIM (Accessory Protocol Interface Module) 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 (Consumer Interface Processor) interfaces with all of the inputs to the APIM (Accessory Protocol Interface Module). It 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 (Consumer Interface Processor) through the USB (Universal Serial Bus) port.

The VIP (Vehicle Interface Processor) provides an interface between the CIP (Consumer Interface Processor) and the vehicle. Its main functions are controlling the APIM (Accessory Protocol Interface Module) power management and translating both inbound and outbound signals over the CAN (Controller Area Network). In addition, the VIP (Vehicle Interface Processor) interrogates the modules on the network to retrieve any DTCs when a vehicle health report is requested.

The APIM (Accessory Protocol Interface Module) can receive inputs from the following audio sources:

- USB (Universal Serial Bus) port

- Audio input jack

- Bluetooth

The USB (Universal Serial Bus) 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 (Universal Serial Bus) port can also be used for uploading vehicle application upgrades.

The USB (Universal Serial Bus) port is powered by the APIM (Accessory Protocol Interface Module), so no external power source is needed to power a device plugged into the USB (Universal Serial Bus) 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 (Audio Control Module). All other functions (such as seek, fast forward, pause, etc.) must be carried out on the device itself.

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 (Accessory Protocol Interface Module) disconnects any active connections 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 (Accessory Protocol Interface Module) from a device plugged into the USB (Universal Serial Bus) port. Metadata consists of such information as artist, album title, song title, and genre. The metadata is used by the APIM (Accessory Protocol Interface Module) to create indexes that can be used to sort for particular music, based on customer preference. Not all USB (Universal Serial Bus) devices send metadata to the APIM (Accessory Protocol Interface Module) ; 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 (Accessory Protocol Interface Module) automatically indexes the information. This may take 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 (Accessory Protocol Interface Module) updates the index (rather than creating a new one), which reduces the amount of time needed to create the index.

The APIM (Accessory Protocol Interface Module) 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. It is also used to send sound to the ACM (Audio Control Module) for voice prompts, the Text-To-Speech (TTS) feature, ringtones, and any audio received through a connected mobile phone. The TTS (Text-To-Speech) feature speaks information so that it does not have to be read from the display.

The APIM (Accessory Protocol Interface Module) communicates on the MS-CAN (Medium Speed Controller Area Network) and High Speed Controller Area Network (HS-CAN). Communication with the scan tool is established through the HS-CAN (High Speed Controller Area Network).

Voice Recognition For Vehicles With Navigation And The SYNC System

When the audio system enters voice recognition mode, the ACM (Audio Control Module) initially controls the voice recognition feature. The microphone is wired directly to the APIM (Accessory Protocol Interface Module), which relays the microphone input to the ACM (Audio Control Module) through dedicated wiring. If the first command spoken is part of the ACM (Audio Control Module) voice recognition set, the ACM (Audio Control Module) retains control of the voice recognition and takes the appropriate action(s). If the first command spoken is part of the APIM (Accessory Protocol Interface Module) voice recognition set, the ACM (Audio Control Module) shuts off its own voice recognition and broadcasts a Controller Area Network (CAN) message to the APIM (Accessory Protocol Interface Module), transferring the voice recognition to the SYNC system and providing the voice command that was spoken. The ACM (Audio Control Module) controls the voice engine for the base audio, navigation, and climate control systems. The APIM (Accessory Protocol Interface Module) controls the voice engine for the SYNC system (USB (Universal Serial Bus) 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 (Audio Control Module) (or the APIM (Accessory Protocol Interface Module)) monitors the change in reference voltage to determine the requested function.

Family Entertainment System

The Rear Entertainment Module (RETM) provides the interface between the DVD players and the rest of the audio system. The family entertainment system allows for single/dual-play mode. The RETM (Rear Entertainment Module) communicates via the MS-CAN (Medium Speed Controller Area Network).

Single-Play Mode

In single-play mode, any audio input routed through the RETM (Rear Entertainment Module) is broadcast through all of the vehicle speakers. These audio inputs include DVD audio, SYNC system audio, and peripheral gaming devices plugged into the DVD player auxiliary input jacks.

Dual-Play Mode

In dual-play mode, the ACM (Audio Control Module) continues to control the output to the front speakers, while the RETM (Rear Entertainment Module) mutes the audio to the rear speakers. The RETM (Rear Entertainment Module) continues to broadcast the rear audio source to the headphones.

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.

Network Communication

The following audio system components communicate via the MS-CAN (Medium Speed Controller Area Network) :

- ACM (Audio Control Module)

- Audio DSP (Digital Signal Processing) module

- FCIM (Front Controls Interface Module)

- RETM (Rear Entertainment Module)

- APIM (Accessory Protocol Interface Module)

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 FDIM (Front Display Interface Module) display

- Dialing phone numbers from the FCIM (Front Controls Interface Module) or FDIM (Front Display Interface Module)

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

Audio System Message List