Principles of Operation

PRINCIPLES OF OPERATION

Audio Unit
The audio unit can be operated while the key is in RUN or ACC. The accessory delay feature allows the audio unit to be operated for a preset period of time after the key is moved to OFF and a front door has not been opened. The audio unit sends AC voltage audio signals to the speakers or to the amplifier, depending on vehicle configuration. The audio unit 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 audio unit self-test by simultaneously pressing presets 3 and 6. The audio unit communicates via the MS-CAN.

Satellite Audio
The satellite audio system consists of a satellite radio receiver, a satellite radio antenna, and an antenna cable. The satellite radio antenna receives digital audio signals and sends them to the satellite radio receiver, where the signals are converted and sent to the auxiliary audio module (or the DVD player, if equipped). The satellite radio receiver communicates via the MS-CAN.

Antenna - AM/FM
The combination AM/FM antenna is located on the right rear quarter-glass. An antenna amplifier is used to amplify the signals to the audio unit. The AM/FM antenna cannot be replaced separately from the quarter glass.

Subwoofer
The Audiophile subwoofer and amplifier are integral. The subwoofer in the THX(R) audio system is powered by the THX(R) amplifier. The enable/clip detection circuit carries out 2 functions: to turn the amplifier on, and to indicate to the audio unit when the subwoofer output distortion signal reaches a damaging level. The audio unit then clips the audio output signal to prevent damage to the subwoofer.

Auxiliary Audio Module
The auxiliary audio module allows rear-seat users to select audio functions. It allows for single/dual-play mode. The auxiliary audio module communicates via the MS-CAN.

Digital Versatile Disc (DVD) Player
When a video disc is inserted into the DVD player and the PLAY button is pressed, an image is displayed on the screen and a stereo signal is transmitted to the audio unit. The DVD player allows for single/dual-play mode. The DVD player communicates via the MS-CAN.

Single-Play Mode
In single-play mode, any audio input routed through the auxiliary audio module (or DVD player) is broadcast through all of the vehicle speakers. These audio inputs include the DVD player and peripheral gaming devices plugged into the auxiliary audio module (or DVD player).

Dual-Play Mode (All Audio Systems Except THX(R))
In dual-play mode, the audio unit continues to control the output to the front speakers, while the auxiliary audio module (or DVD player) controls the audio to the rear speakers and headphones.

Dual-Play Mode (THX(R))
In dual-play mode, the audio unit continues to control all of the vehicle speakers. The auxiliary audio module (or DVD player) controls the audio output to the headphones only.

THX(R) Audio System
The THX(R) audio system provides theatre quality sound in the vehicle. Audio signals are sent to the THX(R) amplifier, which processes the audio signals and sends them to the 12 speakers: 4 door speakers, 2 tweeter speakers, 3 front/center speakers, 2 D-pillar tweeters, and a subwoofer. The THX(R) amplifier communicates via the MS-CAN.

Navigation
The navigation audio unit generates a display on a video screen. When an on-screen menu key is pressed, a new screen is displayed corresponding to the key that was pressed. The navigation audio unit is available with the THX(R) or Audiophile sound systems.

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 audio unit monitors the change in reference voltage to determine the requested function.

Audio Input Jack
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.

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:
- Audio unit
- Navigation audio unit
- Satellite radio receiver
- Auxiliary audio module
- DVD player
- THX amplifier







The following messages are utilized by the audio system.