O2 sensor TOYOTA PRIUS 2001 Service Repair Manual

CHASSIS ± STEERING
182CH95
182CH76
Twist Angle
Basic Position
Cornering
Torque
[V]
Voltage
Voltage difference between
outputs 1 and 2 during
straight line driving (0)
Torque Sensor 2
Torque Sensor 1
0 ±+
Right Turn Left Turn127
ii) Steering to the right
When the driver turns the steering to the
right, the steering torque is transmitted to
the pinion shaft's input shaft, causing the
input shaft to rotate. Because the reaction
force of the ground surface acts on the rack
bar, the torsion bar that links the input shaft
and the pinion twists until a torque that
equalizes with the reaction force is gener-
ated. Thus, a relative displacement is
created between the resistor that is secured
onto the input shaft and the contact that is
secured onto the pinion shaft's output shaft.
As a result, the resistance changes, causing
the torque sensor's outputs 1 and 2 to
change as shown in the right diagram. The
EMPS ECU uses this voltage difference to
calculate the power assist torque to drive
the DC motor, thus generating a power as-
sist force in the pinion shaft via the reduc-
tion mechanism.
iii) Steering Hold Condition
The torsion bar shift to a position in which the sum of the driver's steering torque and the motor's assist
torque equalizes with the reaction force of the ground surface in order to maintain the steering holding
condition.
EMPS ECU
1) EMPS Control
The EMPS ECU receives signals from various sensors, judges the current vehicle condition, and deter-
mines the assist ampere to be applied to the DC motor accordingly.
2) Self-Diagnosis
If the EMPS ECU detects a malfunction in the EMPS system, the warning light that corresponds to the
function in which the malfunction has been detected lights up to alert the driver of the malfunction.
The EMPS ECU will also store the codes of the malfunctions. The DTCs (Diagnostic Trouble Codes)
can be accessed through the use of a hand-held tester. For details, see the 2001 Prius Repair Manual (Pub.
No. RM778U).
3) Fail-Safe
If the EMPS ECU detects a malfunction in the EMPS system, the system basically turns OFF the power
to prohibit power assist. As a result, the EMPS system operates the same way as manual steering.
However, depending on the location in which the malfunction occurred, power assist may be provided
by reducing the power assist amperage or by fixing the amount of power assist without relying on the
vehicle speed.

BODY ± ENHANCEMENT OF PRODUCT APPEAL
182BO16
Gas Pressure from
the Gas Generator
RackBobbinSeat Belt
Planetary Gear
Pinion GearClutch Mechanism
139
SEAT BELT
1. General

The front seats are provided with an electrical sensing type seat belt pretensioner and a seat belt force limit-
er. In the beginning of a collision, the seat belt pretensioner instantly pulls up the seat belt thus providing
the excellent belt's effectiveness in restraining the occupant.
When the impact of a collision causes the tension of the seat belt applied to the occupant to reach a predeter-
mined level, the force limiter restrains the tension, thus controlling the force applied to the occupant's chest
area.

In accordance with the ignition signal from the airbag sensor assembly, the seat belt pretensioner activates
simultaneously with the deployment of the SRS airbags for the driver and front passenger.

The passenger seats are provided with ALR (Automatic Locking Retractor) / ELR (Emergency Locking
Retractor) seat belts.
2. Seat Belt Pretensioner
General
The pretensioner mechanism mainly consists of a rack, pinion gear, planetary gear, clutch mechanism, and
a bobbin.
During the deployment of this pretensioner mechanism, the gas pressure from the gas generator pushes the
rack down and retracts the seat belt via the pinion gear, planetary gear, clutch mechanism, and bobbin.

BODY ± ENHANCEMENT OF PRODUCT APPEAL
174BO02
Energy Absorbing Shaft
Lock Sensor AssemblySeat Belt
Bobbin
Sleeve 140
3. Seat Belt Force Limiter
The seat belt force limiter mainly consists of an energy absorbing shaft, lock sensor assembly, bobbin, and
sleeve.
When the seat belt is pulled out at a rate that exceeds the specified acceleration rate, the ELR (Emergency
Locking Retractor) becomes activated, causing the lock sensor assembly to lock the energy absorbing shaft.
Because the bobbin on which the seat belt is attached is secured to the energy absorbing shaft via the sleeve,
the energy absorbing shaft becomes twisted. The twisting of the energy absorbing shaft causes the bobbin
to rotate and the seat belt to be pulled out, thus maintaining the tension that is applied to the seat belt.

BODY ELECTRICAL ± METER
182BE04
182BE16
U.S.A. Model
Canada Model Master Warning LightOutput Control
Warning Light
ªREADYº Light 146
METER
COMBINATION METER
1. General

The combination meter is available as a digital display type. It is located at the upper center of the instru-
ment panel to improve its visibility.

For this combination meter, a meter ECU that effects multiplex communication through the use of BEAN
(Body Electronics Area Network) has been adopted.

The display of the speedometer can be switched between km / h and MPH readings by operating the km / h-
MPH selector switch located in the middle of the center cluster. Furthermore, the odo / trip meter can be
switched between odometer and tripmeter readings by operating the odo / trip selector / reset switch located
in the middle of the center cluster.

A ªREADYº light that informs the driver that the vehicle is ready to be driven has been adopted.

A master warning light that informs the driver if an abnormality occurs in either the EMPS (Electric Motor-
assisted Power Steering), HV batteries, or the THS (TOYOTA Hybrid System) has been adopted.

An output control warning light has been adopted to show the drop of power function due to the output
drop of HV batteries.

For the purpose of making corrections in the calculation of the fuel level by the meter ECU, two inclination
sensors that detect the vehicle's longitudinal and latitudinal inclinations have been provided in the meter
ECU. In addition, an outer ambient temperature sensor has been provided in the fuel tank to detect the
temperature in the fuel tank.

BODY ELECTRICAL ± METER
182BE05
Km / h-MPH Selector Switch
182BE06
Odo Meter
Trip Meter A
Trip Meter B
Odo / Trip Selector / Reset Switch147
2. Construction and Operation
Speedometer

The speedometer is displayed digitally
through the VFD (Vacuum Fluorescent Dis-
play). It can be switched between the km / h
and MPH readings by operating the km / h-
MPH selector switch located in the middle of
the center cluster.

The vehicle speed signal, which originates at
the speed sensor that is installed in the hybrid
transaxle, travels via the HV ECU and ECM
(BEAN) and is received by the meter ECU.
Odo / Trip Meter
Similar to the speedometer, the odo / trip meter is
displayed digitally through the VFD (Vacuum
Fluorescent Display). By operating the odo / trip
selector / reset switch located in the middle of the
center cluster, its display can be switched in the
following sequence: odometer
trip meter A

trip meter B.
While trip meter A or B is displayed, pressing the
odo / trip selector / reset switch 0.8 seconds or
longer causes the driven distance displayed by
the current trip mode to revert to 0.0 mile or 0.0
km.
The trip meter will resume measuring the dis-
tance at the moment the odo / trip selector / reset
switch is released.

BODY ELECTRICAL ± METER
182BE07
Combination Meter
Sender
Gauge
Meter
ECU
Inclination Sensors
Temperature Signal
Sender
Gauge Signal Fuel Injection
Signal
ECM
Body ECU
Sender
Gauge Signal
Fuel TankAmbient
Temperature Sensor
Fuel Sender Gauge
Main Tank Sub Tank Fuel Pump 148
Fuel Gauge
For the purpose of correcting the calculation of the fuel level by the meter ECU, two inclination sensors
that detect the vehicle's longitudinal and latitudinal inclinations have been provided in the meter ECU, and
an ambient temperature sensor has been provided in the fuel tank to detect the temperature in the fuel tank.
The fuel level is calculated by the meter ECU in accordance with the signals of the sender gauge located
in the sub tank that have been received via the body ECU, and the fuel injection signals received from the
ECM. At this time, corrections are made by the signals from the inclination sensors that detect the vehicle's
longitudinal and latitudinal inclinations and the ambient temperature sensor that detects the temperature in
the fuel tank.

BODY ELECTRICAL ± AIR CONDITIONING
182BE17
PTC Heaters
182BE18
ALT AM1Ignition
Switch
HTR
MAIN
PS
HTR1PTC
HTR1PTC
HTR2
Battery
Heater Core
Integrated
PTC HeaterPTC Heaters
IG
HTR0
Air
Conditioning
ECU
HTR2
GNDMPX
IDH
Switch Signals from
Heater Control Panel
ECM
Body
ECU
Converter
Ambient
Temperature Sensor
Engine Coolant
Temperature Sensor
156
PTC heaters have been provided in the air
duct at the footwell outlet in front of the air
conditioning unit. However, air condition-
ing without the PTC heaters is offered as an
option on the U.S.A. models.
This PTC heater, which is a honeycomb-
shaped PTC thermistor, directly warms the
air that flows in the duct.

Wiring Diagram 

BODY ELECTRICAL ± AIR CONDITIONING
182BE22
Air
Conditioning
ECUBEAN
ECM
Room Temper-
ature SensorEvaporator Tem-
perature SensorSolar SensorAmbient Tem-
perature SensorEngien Coolant
Temperature Sensor
182BE23
Ambient Temperature Sensor165
6. Air Conditioning ECU
General
An automatic control type air conditioning has been adopted. This system uses an air conditioning ECU
to perform the calculation of the required outlet air temperature control, temperature control, blower con-
trol, air inlet control, air outlet control, and compressor control.
The information that is necessary for effecting the controls are the signals from the room temperature
sensor, evaporator temperature sensor, and solar sensor that are directly transmitted to the air condition-
ing ECU, and the signals from the ambient temperature sensor and the engine coolant temperature sensor
that are transmitted via the ECM. These signals are calculated by the air conditioning ECU to effect the
proper control.

System Diagram 
Sensors
1) Ambient Temperature Sensor
The ambient temperature sensor has been pro-
vided on the left, in front of the condenser.
The signals from this sensor are transmitted to
the air conditioning ECU via the ECM.

BODY ELECTRICAL ± AIR CONDITIONING
182BE24Room Temperature
Sensor
182BE25
Evaporator Temperature
Sensor
182BE26
Solar Sensor
182BE27
Engine Coolant
Temperature Sensor 166
2) Room Temperature Sensor
The room temperature sensor has been pro-
vided inside the instrument finish lower panel.
The signals from this sensor are directly trans-
mitted to the air conditioning ECU.
3) Evaporator Temperature Sensor
The evaporator temperature sensor has been
provided behind the evaporator in the air
conditioning unit.
The signals from this sensor are directly trans-
mitted to the air conditioning ECU.
4) Solar Sensor
The solar sensor has been provided on top of
the instrument panel.
The signals from this sensor are directly trans-
mitted to the air conditioning ECU.
5) Engine Coolant Temperature Sensor
The water temperature sensor has been pro-
vided on the water outlet area on the left side
of the engine.
The signals from this sensor are transmitted to
the air conditioning ECU via the ECM.

BODY ELECTRICAL ± AIR CONDITIONING
182BE50
Large
Target
Damper
Opening
Angle
Small
Large Small
Tentative Damper Opening Angle167
Calculation of Required Outlet Air Temperature (TAO: Temperature Air Outlet)
After receiving the signals from the sensors and the temperature control switch setting, the air conditioning
ECU uses the formula shown below to calculate the required outlet air temperature, to regulate the servomo-
tors and blower motor. This is an outlet air temperature that is required in maintaining the set temperature
in a stable manner.
TAO=KSETx TSET±Kr x TR±KAMx TAMdisp±KsxTS+C±TCTA O = KSET x TSET ± Kr x TR ± KAM x TAMdisp ± Ks x TS + C ± TC
KSET= Setting Temperature Coefficient TSET = Setting Temperature
Kr = Room Air Temperature Coefficient TR = Room Air TemperatureKr= Room Air Temperature CoefficientTR= Room Air Temperature
K
AM= Ambient Air Temperature Coefficient TAMdisp = Ambient Air TemperatureAMppp
Ks = Solar Radiation Coefficient TS = Solar Radiation
C = Correct Constant TC = Compressor ON / OFF CorrectC= Correct ConstantTC= Compressor ON / OFF Correct
= Constant
Temperature Control System
1) Air Mix Damper Control
In response to the temperature control switch setting, the required ambient temperature, evaporator tem-
perature sensor, and engine coolant temperature sensor compensations are used by the air mix damper
control to calculate a tentative damper opening angle, through an arithmetic circuit in the air mix damper,
to arrive at a target damper opening angle.

Calculating the Target Damper Opening