Operation CHARM: Car repair manuals for everyone.

Principles of Operation (How Does It Work?)

PRINCIPLES OF OPERATION

When the audio unit is powered up a wake-up signal is sent to the subwoofer amplifier. Audio output signals are then sent continuously to the subwoofer amplifier. These signals are then amplified and sent to the speakers as a fluctuating AC voltage (thus producing sound from the speakers). A fluctuating AC voltage audio signal is also sent to the remaining speakers, directly from the audio unit, to produce sound. The steering wheel controls are a multiplexed system that use different resistor values to produce different voltage levels on a single circuit. Each button that is pressed results in a unique voltage signal at the audio unit. This voltage signal is then interpreted by the audio unit as a distinct command. The audio unit is linked to the SCP network, therefore trouble codes can be obtained with a diagnostic tool. The audio unit also has a self-diagnostic mode that can be entered by pressing preset buttons 3 and 6 simultaneously. The DVD player sends fluctuating AC voltage audio output signals to the audio unit. These signals are then amplified by the audio unit and sent to the speakers.