O2 sensor TOYOTA PRIUS 2001 Service Manual PDF

ENGINE ± 1NZ-FXE ENGINE
ECM
EFI MAIN RELAY BATTERY+B BATT, BM
HTE
ETH
SPHV
ESTP
GO HV ECU
(Hybrid Vehicle Control ECU)
VACUUM SENSOR
(for TOYOTA HCAC SYSTEM)ACCELERATOR PEDAL
POSITION SENSORHCLS
VAPOR PRESSURE SENSORPTNK VPA 1, 2
DATA LINK CONNECTOR 3SIL
TC
AIR CONDITIONING ECU AIR CONDITIONING CUT-
OFF CONTROL
ACT
COOLING FAN RELAYCOOLING FAN
CONTROLFA N
VSV (for EVAP) EVAP CONTROLEVP1
VSV (for CANISTER
CLOSED VALVE) CCV
VSV (for PURGE FLOW
SWITCHING VALVE)TBP
METER ECU
AIR CONDITIONING ECU
DISPLAY ECU
BODY ECU
VSV
(for TOYOTA HCAC SYSTEM)
EFI MAIN RELAY
MALFUNCTION INDICATOR
LAMP MPX1
NEO
MPX2
HCC
MREL
W
64

ENGINE ± 1NZ-FXE ENGINE
182EG22
Circuit
Opening
Relay
VSV
(for
EVAP)
Intake
Air Temp.
SensorThrottle
Position
Sensor
ECMHV
ECU
Accelera-
tor Pedal
Position
Sensor
Cooling
Fan Relay
Throttle
Control
Motor
Igniter
Camshaft Position Sensor
Knock
Sensor
Mass Air
Flow Meter
VSV
(for Toyota
HCAC
System)Vacuum
Sensor
(for Toyota
HCAC
System)
Crankshaft
Position Sensor Injector
Camshaft
Timing
Oil Con-
trol Valve
Engine
Coolant
Te m p .
Sensor
TWC
Heated Oxygen
Sensor (Bank 1,
Sensor 1)
Heated Oxygen
Sensor (Bank 1,
Sensor 2)
Actuator (for HC
Adsorber)
TWC (with HC
Adsorber)
VSV (for Purge Flow
Switching Valve)
Vapor Pressure Sensor
VSV (for Canister Closed Valve)
Charcoal
Canister
Fuel Pump65
3. Engine Control System Diagram

ENGINE ± 1NZ-FXE ENGINE
182EG23
VSV (for TOYOTA
HCAC System)VSV (for EVAP)Oil Control Valve
ECMIgnition Coil
with IgniterVSV (for Purge Flow Switching Valve)
Charcoal Canister
Vapor
Pressure
Sensor
Trap Filter
VSV (for Canister
Closed Valve) DLC 3
Heated Oxygen Sensor
(Bank 1, Sensor 2)
Heated Oxygen Sensor
(Bank 1, Sensor 1) Engien Coolant
Temp. Sensor Camshaft
Position
Sensor
Injector Crankshaft
Position
Sensor Knock
Sensor Throttle
Control
Motor Mass Air
Flow Meter 66
4. Layout of Components

ENGINE ± 1NZ-FXE ENGINE
182EG24
VVT-i Controller
ECM
Camshaft Position
Sensor
Camshaft Timing
Oil Control Valve Crankshaft
Position
Sensor67
5. Main Components of Engine Control System
The main components of the 1NZ-FXE engine control system are as follows:
Components
OutlineQuantity
Mass Air Flow MeterHot-Wire Type1
Crankshaft Position Sensor (Rotor's Teeth)Pick-Up Coil Type (36-2)1
Camshaft Position Sensor (Rotor's Teeth)Pick-Up Coil Type (3)1
Throttle Position SensorLinear Type (Double)1
Knock SensorBuilt-In Piezoelectric Element Type1
Oxygen Sensor
Heated Oxygen Sensor
(Bank 1, Sensor 1)
(Bank 1, Sensor 2)
2
Injector12-Hole Type4
6. VVT-i (Variable Valve Timing-intelligent) System
General
The VVT-i system is designed to control the intake camshaft within a wide range of 43 (of crankshaft
angle) to provide a valve timing that is optimally suited to the engine condition, thus realizing improved
torque in all the speed ranges and fuel economy, and reduce exhaust emissions.

ENGINE ± 1NZ-FXE ENGINE
182EG25
Engine Load
Full Load Performance
Range 4Range 5
Range 3
Range 2
Range 1Engine Speed
TDC
EXIN
BDCLatest
timing
To retard
side
IN
EX
To advance
side
EX IN71
In proportion to the engine speed, intake air volume, throttle position and water temperature, the ECM cal-
culates an optimal valve timing under each driving condition and control the camshaft timing oil control
valve. In addition, ECM uses signal from the camshaft position sensor and the crankshaft position sensor
to detect the actual valve timing, thus performing feedback control to achieve the target valve timing.

Operation During Various Driving Condition (Conceptual Diagram) 
Operation StateRangeValve TimingObjectiveEffect
During Idling1
182EG26
Eliminating overlap to
reduce blow back to the
intake sideStabilized
idling rpm
Better fuel
economy
At Light Load2
182EG27
Decreasing overlap to
eliminate blow back to
the intake sideEnsured
engine
stability
At Medium
load3
182EG28
Increasing overlap to
increase internal EGR for
pumping loss elimination
Better fuel
economy
Improved
emission
control

ENGINE ± 1NZ-FXE ENGINE
182EG39
Front Airbag
Sensors
(RH and LH)Airbag
Sensor
AssemblyHV
ECUCircuit
Opening
Relay
Fuel Pump
Motor ECM73
7. Fuel Pump Control
A fuel cut control is adopted to stop the fuel pump when the SRS airbag is deployed, thus helping reduce fuel
leakage.
In this system, the airbag deployment signal from the airbag sensor assembly is detected by the HV ECU,
send the signal to ECM, which turns OFF the circuit opening relay.
After the fuel cut control has been activated, turning the ignition switch from OFF to ON cancels the fuel cut
control, thus engine can be restarted.

ENGINE ± 1NZ-FXE ENGINE
182EG31
Accelerator Pedal
Position SensorThrottle Valve
Throttle Position Sensor
Throttle Control
Motor
HV
ECUECM
182EG33 182EG32
Accelerator Pedal
Position Sensor(V)
5.0
4.0
3.0
2.0
1.0
0 10 2030 405060 70 80
125Output Voltage
Accelerator Pedal Depressed AngleVPA2
VPA1 74
8. ETCS-i (Electronic Throttle Control System-intelligent)
General
The ETCS-i, which realizes excellent throttle control in all the operating ranges, has been adopted.
In the conventional throttle body, the throttle valve opening is determined invariably by the amount of
the accelerator pedal effort. In contrast, the ETCS-i used the ECM to calculate the optimal throttle valve
opening that is appropriate for the respective driving condition and uses a throttle control motor to control
the opening.
The ETCS-i controls the ISC (Idle Speed Control) system and the cruise control system.

System Diagram 
Construction
1) Accelerator Pedal Position Sensor
The accelerator pedal position sensor is mounted on the accelerator pedal. To detect the pedal opening
angle, 2 separate systems consisting of main and sub sensors are used, and 2 separate return springs are
used to improve reliability. In the detecting portions, Hall elements have been adopted. Due to the charac-
teristics of the Hall elements, different signals are output depending on whether the pedal is pressed all
the way or is released. To correct these signals, a mechanical device has been provided to detect the cor-
rect pedal opening angle. The sensors of the 2 systems output the same signals.

ENGINE ± 1NZ-FXE ENGINE
150EG39150EG40
Close
Open
VC VTA1 VTA2 E2V
5
0 Close
Output Voltage
Open VTA1 VTA2
Accelerator Pedal Depressed Angle75
2) Throttle Position Sensor
The throttle position sensor is mounted on the throttle body.
The throttle position sensor converts the amount of accelerator pedal effort into two types of electrical
signals with distinct output characteristics. The signals are then input into the ECM.
3) Throttle Control Motor
A DC motor with excellent response and minimal power consumption is used for the throttle control mo-
tor. The ECM performs the duty ratio control of the direction and the amperage of the current that flows
to the throttle control motor in order to regulate the opening angle of the throttle valve.
Operation
The ECM drives the throttle control motor by determining the target throttle valve opening in accordance
with the respective operating condition.
1) Idle Speed Control
The idle speed control is effected entirely by the ETCS-i. The following are the contents of the control:
idle-up control during cold engine operation, intake air volume control to improve the startability of the
engine, and control for when the electrical load changes such as when the air conditioning switch is turned
ON or OFF.
2) Cruise Control
Through the adoption of the ETCS-i, the vehicle speed is now controlled by the throttle control motor,
which controls the throttle valve.

ENGINE ± 1NZ-FXE ENGINE
182EG34
Air CleanerIntake Air Chamber
VSV
(for EVAP)
ECM
Fresh Air Line
Purge Line
EVAP Line
VSV
(for Purge Flow Switching Valve)
Charcoal Canister
Recircle Line
Vapor Pressure
Sensor
VSV (for Canister Closed Valve)77
9. Evaporative Emission Control
General
A vacuum system has been newly adopted to detect leaks in the evaporative emission control system. This
vacuum system detects leaks by forcefully introducing the purge vacuum into the entire system and moni-
toring the changes in the pressure.
In order to detect evaporative emission leaks from the vapor reducing fuel tank, a density method has been
adopted. This system uses an oxygen sensor to measure the HC density in the exhaust gases in order to detect
leaks.
It consists of the following main conponents:

A VSV (for canister closed valve) has been provided between the fresh air line and the fuel tank.

The VSV (for purge flow switching valve) switches the passages from the charcoal canister to the purge
line and from the fuel tank to the purge line.

A vapor pressure sensor has been provided in the fuel tank in order to further ensure the precision of the
vapor pressure sensor.

DTCs (Diagnostic Trouble Codes) have been added. For details on the DTCs (Diagnostic Trouble
Codes), refer to the 2001 Prius Repair Manual (Pub. No.RM778U).

ENGINE ± 1NZ-FXE ENGINE 78
Operation
Initially, the VSV (for canister closed valve) is closed, and the VSV (for EVAP) is open, enabling the VSV
(for purge flow switching valve) to keep the passage between the charcoal canister and the purge line open.
This causes a vacuum to be applied to the purge line, evaporator line, recirculation line, and the line from
the charcoal canister to the fuel tank.
Next, the VSV (for EVAP) is closed in order to maintain a vacuum from the VSV (for EVAP) to the inside
of the fuel tank. Then, any subsequent changes in the pressure are monitored by the vapor pressure sensor
in order to check for evaporative emission leaks.
Next, the VSV (for canister closed valve) and the VSV (for EVAP) open, enabling the VSV (for purge flow
switching valve) to keep the passage between the fuel tank and the purge line open. Then, the air in the fuel
tank is drawn in by the vacuum of the intake chamber, and the density of HC in the exhaust gases is measured
by the oxygen sensor to detect any leaks.
If a leak is detected, the malfunction indicator lamp (MIL) illuminates to inform the driver. Also, the diag-
nostic trouble code (DTC) can be accessed through the use of a hand-held tester.
For details on the DTCs, refer to the 2001 Prius Repair Manual (Pub. No.RM778U).
10. HV Immobiliser System
The HV immobiliser system has been designed to prevent the vehicle from being stolen. This system uses
a HV ECU that stores the ID code of the authorized ignition key. If an attempt is made to start the HV system
using an unauthorized key, the HV ECU prohibit fuel delivery, ignition, and starting the HD system effective-
ly disabling the engine.
For details see page 184 in the HV Immobiliser System section.
11. Diagnosis System
The diagnostic trouble codes can be output via DLC3 to an OBD-II scan tool or a hand-held tester. For details,
refer to the 2001 Prius Repair Manual (Pub. No.RM778U).