O2 sensor TOYOTA PRIUS 2001 Service Repair Manual

BODY ELECTRICAL ± AIR CONDITIONING
174BE06
Ex-HI
Blower
Air
Volume
LO
Low
Required Outlet
Air TemperatureHigh[C]
174BE07
HI
Calculated
Air Volume
LO
OFF[C]
Coolant Temperature (a) (b) (c) 168
Blower Control System
1) Blower Motor Startup Control
When the blower motor is started up, the blower voltage in the auto mode (low speed) is output to the
blower controller for 3 seconds. This is designed to protect the blower controller from a sudden startup
current surge.
2) Manual Control
Sets the blower speed according to operation of the blower switch.
3) Automatic Control
a. Stepless Air Volume Control
As shown on the right, when the AUTO
switch on the heater control panel is pushed,
the air conditioning ECU automatically reg-
ulates the voltage to the blower controller, in
accordance with the required outlet air tem-
perature, to deliver stepless air volume.
b. Warm-Up Control
When the coolant temperature detected by the engine coolant temperature sensor is below a predeter-
mined level and the air outlet is in the FOOT or BI-LEVEL mode, the blower does not operate. When
the coolant temperature reaches specified temperature (b), the blower motor operates at low speed.
When the coolant temperature is between specified temperature (b) to (c), the air flow calculation using
the engine coolant temperature sensor signal, and, the air flow calculation using the required outlet air
temperature are compared, and the lesser of the two is automatically selected as the air flow to be used.
When the coolant temperature reaches specified temperature (c) or more, the blower motor runs at high
speed. Moreover, when the coolant temperature is under specified temperature (a), and the warm-up
control is effected (blower motor off), the air outlet is switched to the DEF mode. Later, when the blower
motor turns on, the air outlet changes from the DEF mode to the FOOT or BI-LEVEL mode.

BODY ELECTRICAL ± AIR CONDITIONING
174BE08
Ex-HI
Blower
Air
Volume
LO
0
Time (a) (b) (c)
Sec.
174BE09
Ex-HI
Blower
Air
Volume
LO
0
Time(a) (b) Sec.169
c. Time-Lagged Air Flow Control
2 types of time-lagged air flow control (in accordance with the temperature detected by the evaporator
temperature sensor) help prevent hot air from being emitted from FACE or BI-LEVEL vent.
i) Evaporator temperature sensor at specified temperature or more
As shown in the diagram on the right, this
control turns OFF the blower motor for
approximately specified time (a) and turns
ON the compressor to cool the air condi-
tioning unit.
After approximately specified time (a)
have elapsed, the blower motor rotates in
the manual LO mode, allowing the cooled
air to be discharged from the vents. Thus,
the discomfort that is associated with the
discharge of warm air is prevented.
Between approximately specified time (b)
to (c), the airflow volume according to the
timelagged airflow control and the airflow
volume of the blower control according to
the calculation of the required outlet air
temperature are compared. The airflow
volume is then regulated at the smaller vol-
ume of the two.
After specified time (c) have elapsed, con-
trol is effected by the blower control ac-
cording to the calculation of the required
outlet air temperature.
ii) Evaporator temperature sensor at specified temperature or less
As shown in the diagram on the right, for
approximately specified time (a), the blow-
er motor rotates in the manual LO mode.
Thereafter, up to approximately specified
time (b), the airflow volume according to
the time-lagged airflow control and the air-
flow volume according to the blower con-
trol of the calculation of the required outlet
air temperature are compared. The airflow
volume is then regulated at the smaller vol-
ume of the two.
After specified time (b) have elapsed, con-
trol is effected based on the blower control
according to the calculation of the required
outlet air temperature.

BODY ELECTRICAL ± AIR CONDITIONING
182BE51
Hi
Lo Blower
Air
Volume
Small Large
Amount of Sunligt
182BE28182BE29
1
0
Small Large
Vehicle Speed Fresh Air
Recirculation
182BE52
Outlet Air
Half
Inlet Air
Low High
TAO (Temperature Air Outlet) 170
d. Sunlight Air Flow Control
Controls the blower speed in accordance
with the intensity of the sunlight when the air
outlet mode is at FACE or BI-LEVEL. The
blower low speed can be adjusted up to 4
steps, in response to the sunlight signal re-
ceived from the solar sensor.
2-Way Flow Mode Control
At the time of selecting FRESH mode, air conditioning ECU will judge it as 2-way flow mode when the
blower outlet is selected to FOOT or FOOT / DEF, the tentative air mix damper opening angle is above the
specified valve (MAX HOT), and either the blower volume is more than the specified volume or the vehicle
speed is less than the specified speed.
Half Inlet Air Mode Control
At the time of selecting FRESH mode, air condi-
tioning ECU will judge it as half inlet air mode
when the blower outlet mode is selected to FACE
or BI-LEVEL and TAO (Temperature Air Out-
let) is more than the specified temperature, and
operates both outlet air introduction and inlet air
circulation at the same time.

BODY ELECTRICAL ± ACCESSORIES175
4. Construction and Operation
General
This system mainly consists of a multi-information display, navigation ECU, display ECU, gateway ECU,
GPS antenna and audio unit.
The navigation ECU, display ECU, gateway ECU, and the audio unit all maintain communication through
the AVC-LAN.
Navigation ECU
The navigation ECU is provided on the models with the GPS voice navigation. Based on the map data on
the DVD, signals from the GPS satellites, signals from the built-in gyro sensor, and signals from the ve-
hicle's speed sensor, this ECU calculates the vehicle's present position, direction of travel, and driven dis-
tance, and transmits the data to the display ECU. In addition, it outputs navigation voice instructions.
Display ECU
Upon receiving the vehicle information that is transmitted by the gateway ECU, the navigation information
that is transmitted by the navigation ECU, and the operation information from the audio unit, the display
ECU displays these data on the multi-information display.
Gateway ECU
The gateway ECU transmits the vehicle information to the display ECU in order for it to be displayed on
multi-information display. Because vehicle information is transmitted by the ECUs that maintain commu-
nication on the BEAN (Body Electronics Area Network), the gateway ECU converts this information into
signals for AVC-LAN use and sends it to the display ECU.
GPS Antenna
The GPS antenna is provided on the models with the GPS voice navigation.
The GPS antenna receives signals from the GPS satellites that are located on the orbits that circle the earth
at an approximate altitude of 20,000 km. The GPS satellites continuously transmit orbit signals and the sig-
nal transmission time.
Multi-information Display
The multi-information display has the functions for displaying the map screen, audio screen, information
screen, adjustment screen, interrupt screen, and on-screen.
This system's self-diagnosis function can be displayed and operated on the multi-information display.
For details, refer to the 2001 Prius Repair Manual (Pub. No. RM778U).

BODY ELECTRICAL ± ACCESSORIES 176
1) Map Screen
The map screen is a function that is provided in the GPS voice navigation system.
Based on the map data on the DVD, signals from the GPS satellites, signals from the built-in gyro sensor,
and signals from the vehicle's speed sensor, the vehicle's present position, direction of travel, and driven
distance are calculated and displayed on this screen. This screen has the display functions listed below.
Item
Outline
Heading Up / North UpChanges the orientation of the map.
Front WideDisplays a map in the direction of travel of the vehicle in
an enlarged form.
Stepless Scale DisplayChanges the scale of the map from the basic 11 steps to
an even finer display.
Direct Scale ChangeDirectly select and display the map scale.
Multi-step Scale DisplayChange and display the map scale in 11 stages.
Map DisplayScroll DisplayScrolls the screen to display the desired point on the map.Map Display
Split-view DisplayDisplays different modes on a screen that is split into two
views.
Points-of-Interest
DisplayDisplays selected types of marks on the map.
Taillight-interlocked
Map Color ChangeChanges the displayed color on the map screen when the
taillights are turned ON.
Road Number Sign
Board DisplayDisplays the road numbers on the map.
Hybrid Points-of-interest
SearchNarrows the search by names of the points-of-interest,
category, and areas.
Points-of-interest
Pinpoint DisplayPinpoints and displays the position of the point-of-
interest.
House Number SearchSearches for a house number.
Special Memory PointSets a pre-registered point as a destination point while
driving.
Destination
SearchNearest Points-of-
Interest Search List
Display
Searches nearest points-of-interest and displays a list.
Intersection SearchBy specifying two streets, the point at which they
intersect is set as the destination point.
Emergency SearchPerforms a specific search for hospitals, police stations,
and dealers.
Freeway Entrance / Exit
SearchSearches for the destination by the name of the street that
connects to a freeway entrance / exit.
Route SearchSearches for multiple routes.
Search
Search Condition
DesignationSearches for the recommended, shortest, and other
routes.
SearchRegulated Road
ConsiderationPerforms search while considering regulated roads.
Avoidance AreaAvoids a designated area and searches a route.
(Continued)

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
182BE44
SRS
Warning LightInflator and Bag
for Front Passenger
Front Airbag
Sensor (RH)
Side Airbag
Assembly (RH)
Seat Belt
Pretensioner (RH)
Side Airbag
Sensor (RH) Airbag Sensor
Assembly Seat Belt
Pretensioner (LH) Side Airbag
Sensor (LH) Side Airbag
Assembly (LH)Front Airbag
Sensor (LH)Inflator and Bag
for Driver
182BE45
CollisionImpact
Front Airbag Sensors
Airbag Sensor
Assembly
 Inflator
 (For Driver and Front Passenger)
 Seat Belt Pretensioner
 (LH and RH)
Inflator
(For Right Side or Left Side)
CollisionImpactSide
Airbag
Sensor 188
SRS AIRBAG AND SRS SIDE AIRBAG
The SRS (Supplemental Restraint System) airbags are provided for the driver and front passenger. The
SRS airbags have been designed to help reducing the shocks to the heads and chests of the driver and front
passenger in the event of a frontal impact collision as supplements to the seat belts.
This system is a 3-sensor type airbag system to detect the impact during a front collision using the airbag
sensor assemblies and front airbag sensor, and to make the airbag system and seat belt pretensioner operate
as well.
Also, the function of the ECU to memorize the seat belt wearing condition while inflating the airbag is
added.
The SRS side airbags are provided for the driver and front passenger as an option. The SRS side airbags
have been designed to help reducing the impact energy that is transmitted to the driver and front passenger
in the event of a side collision.
The driver side and the front passenger side are each provided with one sensor.
A fuel cut control has been adopted to stop the fuel pump when the SRS airbag is deployed, thus helping
reduce fuel leakage.

System Diagram 

BODY ELECTRICAL ± ACCESSORIES
182BE46
Cruise Control Switch Signal
Brake Cancel Signal
(Stoplight Switch)
Accelerator Opening Angle Signal
(Accelerator Pedal Position Sensor)
Shift Position Signal
(Sift Position Sensor)
Brake ECUHV ECU
Cruise Control Area

Switch Input Value

Processing

Required Vehicle Speed

Calculation
Hybrid Control Area

Required Torque

Calculation

Drive Force Distribution

between Engine and
Electric Motor
Indicator Light
ECM
Inverter189
CRUISE CONTROL SYSTEM
1. General
The Prius has adopted a cruise control system that uses the hybrid system, and it is offered as an option. This
system, which is controlled by the HV ECU that is integrated with the cruise control ECU, operates the ve-
hicle through an optimal combination of the drive forces of the electric motor and the engine in accordance
with the setting on the cruise control switch.
2. Construction
The cruise control system mainly consists of an HV ECU, cruise control switches, indicator, stoplight switch,
accelerator pedal position sensor, and the shift position sensor.
The table below shows each of the functions.
Item
Function
HV ECUControls all the functions of the cruise control system in accordance with the
signals from the sensors.
Cruise Control Main
SwitchCruise control system's ON / OFF signal requirement.
Cruise Control Switch
A three-directional switch that provides the SET / COAST, RESUME /
ACCEL, and CANCEL functions. It requires the functions and settings in
accordance with its operations.
Indicator LightIt is provided in the combination meter to display whether the system is ON
or OFF.
Stop Light SwitchDetects that the driver has stepped on the brake pedal.
Accelerator Pedal
Position SensorDetects the accelerator pedal opening angle.
Shift Position SensorDetects the shift position.

BODY ELECTRICAL ± ACCESSORIES
182BE47 Warning
Buzzer
(Driver)
Seat Belt
Warning
Light
(Driver)Seat Belt
Warning Light
(Front Passenger Side)
Combination Meter
Seat Belt
Buckle
SwitchOccupant Detection
Sensor
Seat Belt Buckle
Switch
Driver
SideFront Passenger
Side
159BE19 159BE18
182BE53
Occupant Detection Sensor
Front Passenger Seat
Upside ViewSpacerElectrode Sheet
Electrode Sheet
Sensor OFF
Occupant
Sensor ON 190

SEAT BELT WARNING SYSTEM
1. General
A seat belt warning system has been adopted. If the driver's seat belt is not buckled, the warning light flashes
and the buzzer sounds. If the front passenger seat belt is not buckled, it flashes the warning light. When the
ignition switch is turned ON, this system determines whether or not the seat belt is buckled by the ON or OFF
condition of the switch that is provided in the seat belt buckle. The occupant detection sensor provided in
the seat cushion of the front passenger seat determines whether or not an occupant is seated in the front pas-
senger seat.
2. Occupant Detection Sensor
The occupant detection sensor, which is enclosed in the seat cushion of the front passenger seat, is used to
detect whether or not the front passenger seat is occupied.
This sensor, which is shaped as illustrated below, consists of a construction in which two sheets of electrodes
sandwich a spacer. When the occupant is seated, the electrode sheets come in contact with each other through
the hole that is provided in the spacer portion, thus enabling the current to flow.
Thus, the sensor detects whether or not an occupant is seated in the front passenger seat.