Navigation Audio Unit

WARNING: This page is about a different car, the 2005 Lincoln Town Car. However, it is still accessible from the selected car via links, so may be relevant.

When the audio unit is powered up, a wake-up signal is sent to the amplifier. Audio output signals are then sent continuously to the amplifier. These signals are then amplified and sent 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 navigation unit is responsible for generating the displays shown on the video screen display by using video circuits (color generation and display synchronization), between the navigation unit and video screen. When an on-screen menu key is pressed on the video screen display a signal is sent to the navigation unit through the controller area network (CAN) circuits. Refreshed data is then sent through the video circuits, and a new screen is displayed corresponding to the key that was pressed. Diagnostic communication between the navigation unit and the video screen display takes place over the CAN circuits. Refer to NAVIGATION SYSTEM for further information about the navigation system.