Principles of Operation
PRINCIPLES OF OPERATIONThe audio control unit can be powered up when the ignition is in the ON or ACC position. The audio control unit provides audio signals to the speakers, thus producing sound.
The audio control unit directs the audio signals to the speakers through separate positive and negative circuits for each of the 4 audio channels: LH front, RH front, LH rear, and RH rear. The audio control unit provides internal circuit protection for shorts to ground, shorts to B+ battery or shorts between any output circuits.
The subwoofer speaker is powered from a separate subwoofer amplifier. The enable/clip circuit carries out 2 functions: to turn on the subwoofer amplifier, and to indicate to the audio control unit when the subwoofer output distortion signal reaches a damaging level. The audio control unit then reduces the audio output signal to the subwoofer amplifier.
The DVD player receives a wake up signal from the audio control unit through the controller area network (CAN). 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 control unit.
The radio suppression equipment reduces interference transmitted through the speakers by the engine ignition and electrical systems.
The steering wheel audio control consists of a specific resistor value for each button function creating a voltage divider. When a button is pressed, a specific reference voltage is sent to the audio control unit. The audio control unit then uses this reference voltage to determine which control input function has been selected.