How the Circuit Works
Navigation SystemHow the Circuit Works
Diagram 156-4 (EX-L):
System Diagram
Overview
The Honda Navigation System is a highly sophisticated hybrid locating system that uses satellite inputs and a map database to show the vehicles current location and to guide the driver to a desired destination. The navigation system receives signals from the global positioning system (GPS). The system is comprised of a network of 24 or more satellites in orbit around the earth. By receiving signals from several of these satellites, the navigation system can determine the approximate latitude, longitude and elevation of the vehicle. In addition, signals from the system's yaw rate sensor and the PCM (vehicle speed pulse) enable the system to keep track of the vehicle's direction and speed of travel. Because of this, the navigation system can keep track of the vehicle's position even when satellite signals cannot be received.
The Honda navigation system has advantages over systems that are entirely self-contained or those which completely rely on the GPS for vehicle position. The navigation system applies the location, direction, and speed information to the maps and calculates a route to the destination entered. As you drive to that destination, the system provides both visual and audio guidance.
The navigation system provides a trip computer function. The fuel economy display is calculated by data provided from the PCM/Gauge assembly via the F-CAN bus, and a dedicated speed signal (VSP).
Power Supply
Fuse 7 (hot at all times) and fuse 32 (hot in acc or on) in the under-dash fuse/relay box supplies battery voltage to the navigation display unit and to the navigation unit.
With the ignition switch in ACC (I) or ON (II) battery voltage is applied through fuse 9 to the navigation unit and to the navigation display unit.
Display Unit
The dash mounted display unit uses a liquid crystal display (LCD). The LCD is a 7-inch diagonal thin film transistor (TFT), stripe type with 280,800 picture elements. The color film and fluorescent light are laid out on the back of the liquid crystal film. The display touch system consists of a grid of 20 vertical and 9 horizontal infrared beams shining across the screen, creating 180 sensing locations. When your finger interrupts these beams, or touches a hard button the signal is sent via the GA-NET bus to the navigation unit. Resting you fingers on the rim of the display can interfere with the touch function.
The display unit, audio unit, and climate control unit are serviced as a single assembly (Audio-HVAC Display Module)). These three components interact with each other via internal ribbon cable connections to a common "motherboard". The "motherboard" supplies the audio-HVAC sub display unit (upper display) with navigation clock time, driver's and front passenger's temperatures, and audio information.
Navigation Unit
The navigation unit calculates the vehicle's position and guides the driver to the desired destination. The unit performs map matching correction (updates the position of the vehicle icon to the streets on the map, when on digitized roads), GPS correction, and distance tuning (adjusts for tire wear and pressure difference). It also controls the menu functions and the DVD-ROM drive. The navigation unit creates and transmits the red-blue-green (RBG) color and sync signals to the display unit. The navigation unit receives the microphone voice input, matches the command against the recognized vocabulary, and performs the appropriate navigation, climate or audio function. Voice command prompts are output along with a muting signal to the audio system. The illumination input is used to switch between the "Day", and "Night" display modes. Because the speed pulses have no direction associated with them, the reverse signal lets the navigation unit know to make the vehicle icon go backwards on the map.
Audio Unit
The audio unit's speakers are used to provide voice guidance. When the navigation unit issues voice guidance, a muting signal is sent to the audio unit, which mutes the front speakers and routes the voice guidance to them. When using the navigation voice control system (TALK, or BACK buttons) all speakers are temporarily muted when you give voice commands, or if the system is providing voice feedback.
GA-Net II Bus
The GA-Net II bus connects the navigation display to the navigation control unit. This communication bus passes hard button and touch sensing information from the display to the navigation control unit. The GA-Net II bus is also used by the navigation unit to pass climate and audio commands (initiated by voice control) to the display unit. In addition the GA-Net II bus is used to communicate with the XM receiver (04 model), and other audio accessories that may have been added.
GPS Antenna
The GPS antenna amplifies and transmits the signals received from the satellites to the GPS receiver. The navigation control unit provides 5 volts to the electronics in the antenna through the antenna cable's conductor. The antenna electronics filter and amplify the satellite signal before sending it to the GPS receiver, which is located in the navigation control unit.
GPS Receiver
The GPS receiver is built into the navigation unit. It calculates the vehicle's position by receiving the amplified satellite positioning signals from the GPS antenna. The GPS receiver's output is used to position the vehicle position (VP) icon accurately on the map.