Principles of Operation

WARNING: This page is about a different car, the 2010 Lincoln Town Car. However, it is still accessible from the selected car via links, so may be relevant.

Standard Audio

When the audio unit is powered up, audio output signals are sent continuously to the speakers as a fluctuating AC voltage, thus producing sound from the speakers. 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 has a self-diagnostic mode that can be entered by pressing preset buttons 3 and 6 simultaneously.

Rear Auxiliary Audio Controls

The rear auxiliary audio controls (if equipped) allow control of certain audio functions by the rear seat passengers. The rear auxiliary controls are located on the top rear of the center console. The signals are sent to the rear audio and temperature control (RATC) module, which sends the signals to the audio unit through the audio corporate protocol (ACP) network.