sat nav LEXUS LS430 2003 Factory Repair Manual

Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
1.Navigation system outline
a. Vehicle position tracking methods
It is essential that the navigation system correctly tracks the current vehicle position and displays it
on the map. There are 2 methods to track the current vehicle position: autonomous (dead
reckoning) and GPS* (satellite) navigation. Both navigation methods are used in conjunction with
each other.
* GPS (Global Positionin
g System)

HINT:
The combination of autonomous and GPS navigation makes it possible to display the vehicle
position even when the vehicle is in places where the GPS radio wave cannot receive a signal.
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57004b004800030050004400530053004c0051004a00030044[ccuracy may slightly decline.
Fig. 5: Identifying GPS Satellite

Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
b. Autonomous navigation
This method determines the relative vehicle position based on the running track determined by the
gyro and vehicle speed sensors located in the navigation ECU.
1. Gyro sensor
Calculates the direction b
y detecting angular velocity. It is located in the radio and navigation
map disc.
Map MatchingThe map data from the map disc is compared to the vehicle position and
running track data. Then, the vehicle position is matched with the
nearest road.
GPS CorrectionThe vehicle position is matched to the position measured by GPS. Then,
the measurement position data from the GPS unit is compared with the
vehicle position and running track data. If the position is widely
different, the GPS measurement position is used.
Distance CorrectionThe running distance signal from the vehicle speed sensor includes the
error caused by tire wear and slippage between the tires and road
surface. Distance correction is performed to account for this. The
navigation ECU automatically offsets the running distance signal to
make up for the difference between it and the distance data of the map.
The offset is automatically updated.

assy.
2. Vehicle speed sensor
Used to calculate the vehicle running distance.
c. GPS navigation (Satellite navigation)
This method detects the absolute vehicle position using radio wave from a GPS satellite.
* GPS satellites were launched by the U.S. Department of Defence for military purposes.
Fig. 6: Identifying Autonomous Navigation

Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
NUMBER OF SATELLITES CHART
d. Map matchin
g
Number of
satellitesMeasurementDescription
2 or lessMeasurement
impossibleVehicle position cannot be obtained because the number of
satellites is not enough.
32-dimensional
measurement is possibleVehicle position is obtained based on the current longitude
and latitude. (This is less precise than 3-dimensional
measurement)
43-dimensional
measurement is possibleVehicle position is obtained based on the current
longitude, latitude and altitude.

The current driving route is calculated by autonomous navigation (according to the gyro sensor and
vehicle speed sensor) and GPS navigation. This information is then compared with possible road
shapes from the map data in the map disc and the vehicle position is set onto the most appropriate
road.
Fig. 7: Identifying Map Matching

Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
2.DVD (Digital Versatile Disc) player outline (for navigation map)
a. The navigation ECU uses a laser pickup to read the digital signals recorded on a DVD.
HINT:
Do not disassemble any part of the navigation ECU.
Do not apply oil to the navigation ECU.
Do not insert anything but a DVD into the navigation ECU.
3.Multi-display outline
a. Touch switch
Touch switches are touch-sensitive (interactive) switches operated by touching the screen. When a
switch is pressed, the outer glass bends in to contact the inner glass at the pressed position. By
doing this, the voltage ratio is measured and the pressed position is detected.