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 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 turned to OFF and a front door has not been opened. The ACM sends AC voltage audio signals to the speakers or to the subwoofer 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).
Front Controls Interface Module (FCIM)
The Front Controls Interface Module (FCIM) is the customer interface to the ACM. It is separate from the ACM, and utilizes the MS-CAN to send button press information to the ACM.
Front Display Interface Module (FDIM)
The Front Display Interface Module (FDIM) is a stand-alone module. It receives message for all of its displays, which include:
- Audio information
- Climate control fan speed and temperature setting
- Outside air temperature
- Compass heading
The FDIM communicates over the MS-CAN.
Satellite Audio
The satellite audio system consists of the ACM, the satellite radio antenna, and the satellite radio antenna cable (part of the AM/FM/satellite radio combination antenna). The satellite radio antenna receives digital audio signals and sends them to the ACM.
Antenna
The fixed-mast antenna receives AM/FM radio waves and sends them to the ACM via the antenna co-axial cable.
If the vehicle is equipped with satellite audio, a combination AM/FM/satellite radio antenna is utilized. The combination antenna receives voltage from the ACM to amplify the satellite audio signal.
Subwoofer
The Audiophile subwoofer is powered by a dedicated amplifier. The amplifier is controlled by the enable/clip detection circuit, which 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.
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 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 sources:
- USB port
- Audio input jack
- 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.
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.
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 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 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 can 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 Global Positioning System Module (GPSM) provides vehicle location for real-time traffic reports and re-routing, and for identifying vehicle location in the event of a collision. The vehicle location information is broadcast to the APIM over the MS-CAN.
The APIM communicates via the MS-CAN and High Speed Controller Area Network (HS-CAN). Communication with the scan tool is established through the HS-CAN.
Steering Wheel Controls
The steering wheel controls consist of a series of resistors. Each steering wheel controls 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.
On vehicles equipped with the SYNC system, the PHONE (an icon of a phone and an up-and-down arrow), VOICE (an icon of someone speaking), and OK buttons interface directly with the APIM, while the other audio steering wheel controls interface with the ACM.
Audio Input Jack
The audio input jack allows for a portable MP3 audio device to be connected to the vehicle audio system. When a portable MP3 player is connected, audio from the MP3 audio device can be played through the vehicle speakers. The audio stream from the audio input jack routes to the APIM if the vehicle is equipped with the SYNC system, or directly to the ACM if the vehicle is not equipped with the SYNC system.
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.
Audio Signals
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. A 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.
On vehicles equipped with the SYNC system, all of the audio signals that the ACM receives are provided by the APIM. The only audio signals that the ACM produces on its own are those generated while the audio system is in radio tuner (AM/FM) mode.
Network Communication
The following audio system components communicate via the MS-CAN:
- ACM
- FCIM
- FDIM
- APIM
- GPSM
There are numerous messages internal to the audio system. The functions of these message include (but are not limited to):
- Changing the audio source
- Updating the FDIM display
In addition, the following messages are utilized by the audio system in conjunction with systems outside of the audio system:
