2001 TOYOTA PRIUS Service Repair Manual

BODY ELECTRICAL ± ACCESSORIES179
5. GPS (Global Positioning System) Voice Navigation
General
The GPS (Global Positioning System) function receives, via an GPS antenna, the signals that are trans-
mitted from the GPS satellites located in space at an approximate altitude of 20,000 km, in order to deter-
mine the vehicle's present position.
The GPS voice navigation function combines the radiowave navigation system that determines the pres-
ent position through the GPS signals, and the self-contained navigation system that detects the driven
distance and the direction of travel through the speed sensors and the gyro sensor that is contained in the
navigation ECU. The GPS voice navigation function is a high-precision navigation system that indicates
the vehicle position on the map display on the DVD and guides the route from the present position to the
destination on a map and pictogram and through voice instructions.
The multi-information display shows the data that has been calculated by the radiowave navigation sys-
tem and the self-contained navigation system.
Construction and Operation
The GPS voice navigation function consists of the following components:
GPS Antenna
Speed Sensor
GPS Receiver (contained in the navigation ECU)
Gyro Sensor (contained in the navigation ECU)
Navigation ECU
Speaker
For details on the basic operation of the GPS antenna and the navigation ECU, see page 175.
1) Speed Sensor
The navigation ECU will receive the vehicle speed signal directly from the meter ECU.
2) GPS Receiver
The GPS receiver demodulates the signals that are received by the GPS antenna from the satellites and
outputs them to the navigation ECU.

BODY ELECTRICAL ± ACCESSORIES
Vibration DirecitonTurning Axis Center
Coriolis Force
Detection Portion
182BE49
180
3) Gyro Sensor
The gyro sensor is designed to detect the yaw rate of vertical axis turn of the vehicle and installed in the
Navigation ECU.
The gyro sensor has a turning-fork shape type piezoelectric ceramic piece inside. This piezoelectric ce-
ramic piece deforms by charging voltage and generates voltage by deforming with force.
The piezoelectric ceramic piece inside the gyro sensor is vibrated by the driving circuit and when the
vehicle turns (when the detection portion turns to the axis direction), coriolis force is added to the detec-
tion portion. With this force, the detection portion is twisted. The voltage generated by this twisting is
signal-processed inside the gyro sensor and outputted.
Navigation ECU receives this signal and judges the yaw rate of the vehicle.
4) Speaker
Outputs the sound signals that are transmitted from the power amplifier. Also outputs the navigation
voice instructions via the front left speaker.

BODY ELECTRICAL ± ACCESSORIES
151LBE24
GPS Sateilites
Difference
Difference
Difference
Difference181
5) Detecting the Vehicle Position
The navigation ECU calculates the position based on the principle of a 3-point measurement.
The GPS satellites are equipped with high-precision clocks. Thus, the satellites are able to transmit con-
tinuous orbit signals and radiowave transmission time signals.
The navigation ECU also contains a clock, which can understand the radiowave time signals that are re-
ceived from the satellites.
As a result, the length of time that is taken by the radiowaves to arrive from the satellites to the antenna
can be determined. Thus, the lengths of time that elapse for the radiowaves of the 4 satellites to reach
the antenna are measured. Each of these lengths of time are multiplied by the luminous flux (the rate of
transmission of luminous energy: approximately 300,000 km per second), the results of which are the
distances from the satellites to the antenna. Because the positions of the GPS satellites are known by their
signals, the receiving point (vehicle position) can be rendered as the point in which the 4 spheres (of
which the centers are the respective satellites) converge.
However, due to the differences that exist between the clocks of the satellite and the ECU, the 4 spheres
do not converge at a single point. Therefore, the ECU uses another satellite to calculate the point at which
the 4 spheres converge at a single point and corrects its internal clock. As a result, the ECU determines
the vehicle position and adjusts its internal clock to the clocks of the satellites.

BODY ELECTRICAL ± ACCESSORIES
182BE40
Power
Window
Master
SwitchUART
Body
ECUFront
Passenger
Switch
Rear LH
Passenger
SwitchRear RH
Passenger
Switch 182
POWER WINDOW SYSTEM
The power window system has the following features:
This system includes one-touch auto-up and down and key-off operation function. The one-touch auto up
and down function automatically fully closes and opens the driver's side window. The key-off operation
function makes it possible to operate the power windows for approximately 45 seconds after the ignition
key is turned to the ACC or LOCK position, if the front doors are not opened.
Also, a jam protection function has been adopted to the closing operation of the driver's window. If a for-
eign object becomes jammed in the window during one-touch auto-up or key-off operation of the driver's
window, this function automatically stops the power window and moves it downward.
This system controls the driver's door through the power window master switch, and the front passenger
and rear passenger doors through the body ECU. The power window master switch and the body ECU
maintain communication through the UART (Universal Asynchronous Receiver Transmitter).

System Diagram 

BODY ELECTRICAL ± ACCESSORIES
182BE41
RRP DBody
ECUUARTPower
Window
Master
SwitchDoor Control
Switch (Manual)
Door Control
Switch (Key-linked)
169BE10
Key Unlock
Warning SwitchDoor Courtesy
Switch
Door Lock
MotorsBody
ECU
Serial Data Link
Wireless Door
Control Receiver
Horn
RelayHeadlight
RelayTaillight
RelayTransmitter183
DOOR LOCK CONTROL SYSTEM
The door lock control system has the following features:
This system has a ªkey-linked lock and unlockº, ªkey-confine preventionº and ªmanual unlock prohibi-
tionº functions.
A 2-step unlock function is provided to unlock the driver's door by turning the key cylinder first and to
unlock passenger's door by turning it the second time.
The control of this system is effected by the body ECU. The door lock control signal from the driver's door
is transmitted from the power window master switch to the body ECU through the UART (Universal
Asynchronous Receiver Transmitter).
If you unlock using the ignition key from the conditions in which all the doors are locked, the dome light
will be lighted.

System Diagram 
WIRELESS DOOR LOCK REMOTE CONTROL SYSTEM
The wireless door lock remote control system has the following features:
In this system, the wireless door control receiver performs the code identification process and the body
ECU effects the door lock control. Serial data link is provided for communication between the wireless
door control receiver and the body ECU.
A key-holder type transmitter has been adopted, and it contains the following three switches: the door lock
switch, door unlock switch, and panic switch.
A rolling code system, in which the signal configuration changes each time when a signal is transmitted
by the transmitter, has been adopted.
Panic alarm operation has been adopted.
The verification light function has been adopted. When the transmitter is used to lock or unlock the doors,
this function flashes the taillights to inform that the operation has been completed. However, at the time
of unlocking, the dome light will be lighted.