Principles of Operation

Information and Entertainment System

Principles of Operation

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 off 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).

Audio Control Module (ACM) Illumination

The base (AM/FM) ACM has a hardwired illumination circuit from the Body Control Module (BCM). For all other ACMs, the illumination signal is received from the BCM via the MS-CAN.

Satellite Audio

The satellite audio system consists of a satellite radio receiver (integral to the ACM), a satellite radio antenna, and a satellite radio antenna cable. The satellite radio antenna receives digital audio signals and sends them to the ACM.

Sony(R) Sound

The Sony(R) sound system provides optimal quality sound in the vehicle. Audio signals are sent from the ACM to the audio Digital Signal Processing (DSP) module, which process the audio signals and sends them to all of the speakers. The audio DSP module uses internal software to produce an optimal sound environment. A mute circuit to the audio DSP module controls allows the ACM to mute the audio output. The audio DSP module is enabled through software. The audio DSP module communicates on the MS-CAN.

Navigation System

The 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. The ACM calculates route information based on GPS data. The GPS antenna tracks several satellites simultaneously. The ACM uses vehicle speed and transmission gear selected signals received through the MS-CAN to detect vehicle speed and direction, resulting in more accurate navigation tracking.

The navigation display is shown on the FDIM. Either the FDIM touchscreen or the buttons on the FCIM can be used to interact with the navigation system.

The compass heading is derived from the GPS 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. A microphone provides a direct input to the ACM. The microphone is shared with the SYNC(R) system, if equipped.

If equipped with a rear view camera, the video feed for the camera is provided by the rear view camera while the vehicle is in REVERSE. Refer to Parking Aid Testing and Inspection for information on the rear view camera.

SYNC(R) System

The SYNC(R) system allows interaction with several types of customer devices, including mobile phones and media devices. The system consists of the APIM, a microphone, the 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 the Consumer Interface Processor (CIP) and the Vehicle Interface Processor (VIP). The modules are not replaceable separately, but can be flashed independently, if required.

The CIP interfaces with all of the inputs to the APIM. 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 through the USB port.

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

The APIM can receive inputs from the following audio 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 flash drive). When playing media files stored on a mass storage device, the SYNC(R) 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 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.

The Bluetooth interface can accommodate both Bluetooth-enabled mobile phones and Bluetooth-enabled media devices. Any Bluetooth device used with the SYNC(R) 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 anytime. 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(R) 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 APIM uses the metadata to create indexes that can be used to sort for particular music, based on customer preference. Not all USB devices can 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(R) system, the APIM automatically indexes the information. Depending on the amount of data on the device, this may take several minutes and is considered normal operation. When a device that was previously connected to the SYNC(R) system is reconnected, the APIM updates the index (rather than creating a new one), which reduces the amount of time needed to index the device.

The APIM receives both stereo and mono sound inputs, and can also transmit both stereo and mono sound. The mono function receives the microphone input. It also sends 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 on the MS-CAN and the High Speed Controller Area Network (HS-CAN). Communication with the scan tool is established through the HS-CAN.

Global Positioning System Module (GPSM)

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 (part of the e911 feature). The vehicle location information is broadcast to the APIM over the CAN.

Voice Recognition For Vehicles With The SYNC(R) 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 CAN message to the APIM, transferring the voice recognition to the SYNC(R) 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(R) system (USB port, audio input jack and Bluetooth).

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 Steering Column Control Module (SCCM) monitors the change in reference voltage to determine the requested function. The SCCM sends the switch information to the BCM over the HS-CAN. The BCM gateways the information to the ACM or the APIM over the MS-CAN.

Audio Input Jack

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 and pause) must be carried out on the device itself.

AM/FM Antenna

A coaxial antenna cable connects the AM/FM antenna to the ACM.

Global Positioning System (GPS) Antenna

For vehicles equipped with navigation, the GPS antenna receives information from satellites. The compass heading is also derived from the GPS signal. A quad-band antenna is utilized.

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. 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 output from the APIM utilizes separate circuits from the stereo output.

A digital signal transmits 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 broadcasts audio signals from a Bluetooth media device to the APIM, which converts the wireless audio signal to analog and relays it to the ACM.

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:

- ACM
- Navigation ACM
- Audio DSP module
- FCIM
- FDIM (vehicles without navigation)
- APIM
- GPSM

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 display
- Dialing phone numbers from the FCIM or FDIM (if equipped with the SYNC(R) system)

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

Battery Load Shed

The BCM uses the battery current sensor to keep track of the battery state of charge. The battery current sensor is a hall-effect sensor attached to the battery ground cable. When the engine is off, and the BCM determines the battery state of charge is below 40% or 10% of the charge has been drained or 45 minutes have elapsed, a load shed message is sent over the Controller Area Network (CAN). This message turns off the audio/navigation system to save the remaining battery charge. Under this condition, SYS OFF TO SAVE BATT is displayed on the Front Display Interface Module (FDIM) to notify the driver that battery protection actions are active.

Engine off load shed occurs when the engine is not running, and the ignition is in the ACC or RUN position. To clear the load shed state, restart the engine.