Head Unit: General
The audio/navigation system head unit is located in the dashboard. The unit contains a DVD player, GPS receiver with gyro, and touchscreen.
The head unit is connected to the wiring harness and bus via three 16-pin connectors. The purpose of the head unit is, as the central audio and navigation unit, to control the system's units and functions.
The head unit's 6.5" touchscreen is used as the control panel and main display window, enabling the control of the system. The left-hand side of the touchscreen surround has a number of buttons - DVD eject, On/Off, navigation, sound source, display and system settings - and a volume knob.
Turn the system on with the On/Off button. Select audio or navigation with the SRC (audio) or NAV (navigation) button. All subsequent selections use the touchscreen, such as radio presets and choosing a destination for navigation.
The head unit contains a GPS receiver that receives signals from the GPS antenna and calculates the position of the car. The head unit also contains a gyro so that the system knows in which direction the car is travelling. The navigation system uses the gyro, DVD (digital maps), vehicle speed from the ESP control module, and GPS to make the calculations required for navigating to a destination.
The head unit communicates with the various other units and systems via the car's bus and wiring harnesses.