Circuit Description

How the Circuit Works (USA: EX, Si)

Diagram 156-24:

This navigation unit 2-DIN assembly consists of the navigation unit, audio unit, and display panel. Additional components of the navigation system include the GPS Antenna, Microphone, Voice Control Switch, Stereo Amplifier (2-door), and the front speakers. Signals from the system's yaw rate sensor (inside the navigation unit) detects the vehicle turning while the ECM/PCM vehicle speed pulse (VSP), and reverse signal enable the system to keep track of the vehicle's speed, and direction of travel. The navigation unit generates the screen graphics, and then displays them on the navigation display.

Power Supply
Fuse 23 (in the under-hood fuse/relay box) is hot at all times and supplies battery voltage to the navigation unit. With the ignition switch in ACC (I) or ON (II), battery voltage is supplied through fuse 35 (in the under-dash fuse/relay box) to the navigation unit. Both fuses are located in the under-dash fuse box.

User Controls
The navigation system can be controlled in three ways; (1) voice commands, (2) hard button inputs, and (3) touch screen inputs. The voice commands are communicated to the navigation unit by the microphone in the roof console when the TALK switch on the steering wheel is pressed. The navigation unit compares the microphone signal with a library of stored voice files in order to find a match. When the voice control system is in use, all of the speakers are muted. Most of the navigation, audio functions can be controlled with voice commands. Refer to the Navigation System Owner's Manual, or to the "Voice Command Help" information screen for a list of valid voice commands.

Navigation Function
The navigation system utilizes the GPS signals obtained by the GPS antenna, the vehicle speed signal from the ECM/PCM, and the yaw rate sensor contained in the navigation unit to get a user from a starting position to a destination. The GPS signals, the vehicle speed and reverse signals, and the yaw rate sensor determine the position of the vehicle icon on the map. The navigation system relies on DVD maps, and points of interest (P01) in order to provide the user with the optimum route between starting and destination positions.

Audio Functions
The audio section of the navigation unit consists of the AM/FM tuner, external XM tuner, the CD player, PC card slot (digital media reader), and the amplifier and speakers. The audio features can be controlled using the hard buttons surrounding the display, or from the "Audio" screen display.

XM
The XM receiver is controlled using the GA-Net Bus.

CD Player
The single slot CD player can play CD, CD-R, MP3 or WMA formats. The audio screen can display track, artist, and album information (if available).

NOTE: Always advise customers to avoid stick-on labels for burned discs. Labels can lift and curl in a hot car and jam the CD mechanism. Recommend writing information on the disc with a marker pen.

PC Slot
This slot (located behind the display screen) is for playing MP3 or WMA audio files. The slot takes a standard type 2 PCMCIA adaptor with a flash memory device such as a Compact Flash, or SD Flash memory. These devices can be purchased at any computer store. The limits for music on any one card are 999 tracks (files), 99 folders, and 9 levels of directories. Only WMA and MP3 files can be played.

See the audio section in the shop manual for more information about troubleshooting PC card issues.

Route Guidance
When en route to a destination, the navigation system provides turn-by-turn map and voice guidance. The navigation system outputs the navigation voice guidance prompts to the front speakers. During navigation voice guidance prompts, the normal audio signal to the front speakers is muted, while the rear audio continues to play.

GPS Signal Reception
The GPS signals obtained by the GPS antenna are provided by 24 or more GPS satellites in orbit. The navigation unit supplies the GPS antenna with 5 V through a coax cable to power the antenna's amplifier. The GPS receiver in the navigation unit receives the amplified GPS signals back through the same coax cable. The GPS receiver identifies the satellites, and processes the different GPS signals. These signals are then converted to actual locations by the navigation unit in order to determine the position of the vehicle.

NOTE: Metallic window tinting, electronic accessories such as radar detectors or cell phones, and other loose items sitting on the dashboard can interfere with GPS signal reception.

GA-NET BUS
The GA-Net bus allows control of audio components such as the XM receiver and other audio accessories. Information passed on the bus includes audio/XM channel selections and XM station/music title names. Because the bus is shared among audio components, any open or short in the GA-Net bus harness will cause any or all of these functions to become inoperative.

Display-Clock
The time on the navigation display is updated by the navigation unit and is accurate to a second. The time is automatically adjusted for daylight savings time and when driving across time zone borders. When the battery is disconnected, the internal GPS clock is reset to "0:00." The clock will reset to the correct time after the system finishes the GPS initialization. If necessary, settings can be adjusted in the navigation "Setup" menu.

Illumination
The navigation unit automatically switches the display mode between the "night", and "day" settings using the headlights. When the headlights are on, the navigation display goes into the night display mode. If the dash brightness control setting is increased to full brightness using the "+" button, then this overrides the "night" display mode and allows a daytime navigation display with the lights on.