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 amplifiers, depending on vehicle configuration. The audio unit can produce its own diagnostic trouble codes (DTCs), which can be communicated to the diagnostic tool through the controller area network (CAN), or can be retrieved through the audio unit self-test by simultaneously pressing presets 3 and 6.

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.

Antenna
The antenna receives both AM and FM radio waves. The antenna is built into the rear window glass and has a module to interpret the audio signals. The audio signals are then sent to the audio unit through the antenna cable.

Subwoofer
The subwoofer speakers are powered by the subwoofer amplifier (Audiophile) or by the audio amplifiers (THX(R)). 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.

THX(R) Audio System
The THX(R) audio system provides theatre quality sound in the vehicle. Audio signals are sent to the digital signal processing (DSP) module, which processes the audio signals and sends them to 2 separate audio amplifiers. From the audio amplifiers, the audio signals are sent to the 12 speakers: 4 door speakers, 2 tweeter speakers, 3 front/center speakers, 1 rear/center speaker, and 2 subwoofer speakers.

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 only available with the THX(R) sound system.

Steering Wheel Controls
The steering wheel controls consist of a specific resistor value for each function creating a voltage divider. When a switch is pressed, a specific reference voltage is sent to the audio unit. The audio unit then uses this reference voltage to determine which control input function has been selected.