Principles of Operation

WARNING: This page is about a different car, the 2006 Mercury Grand Marquis and 2006 Ford Crown Victoria. However, it is still accessible from the selected car via links, so may be relevant.

When the audio unit is powered up, a fluctuating AC voltage audio signal is sent from the audio unit to the speakers to produce sound. For vehicles equipped with an optional subwoofer, 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 amplified and sent to the subwoofer speakers as a fluctuating AC voltage.

The steering wheel controls are a multiplexed system that use a series of resistors 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 specific preset buttons simultaneously. For additional information, refer to the SPEAKER WALK-AROUND TEST and the AUDIO UNIT SELF-DIAGNOSTIC MODE .