gas type TOYOTA PRIUS 2001 Service Repair Manual

NEW MODEL OUTLINE
182MO18
182MO19
182EG03
kW
60
50
40
30
20
10 N´m
120
11 0
100
90
80
Engine Speed (rpm) 1,000 2,000 3,000 4,000 5,000(52/4,500)
(111/4,200)
Torque
Output
15
HV Battery Charging
When high load operation is continued, the engine
does not stop to charge the HV battery even
if the vehicle is stopped, in order to keep the
HV battery charged to a given level. (when
ªREADYº light is ON.) ;however, the engine does
not charge the HV battery when the lever is
shifted into the ªNº position.
The engine speed may also be increased during normal
traveling in order to charge the HV battery.
1NZ-FXE Engine
The new Prius is fitted with a 1.5
gasoline engine which has been developed for the use with the TOYOTA
hybrid system. A mass of leading-edge technology has been implemented to achieve excellent fuel economy,
low emissions, light weight, compactness, and low vibration and noise.
Outline of the 1NZ-FXE Engine Engine performance curve
1NZ-FXE
Displacement (m
)1,497
TypeDOHC 4 valves
Bore y Stroke (mm)75.0 y 84.7
Compression ratio13.0
Maximum output [kW (HP)/rpm]52 (70)/4,500
Maximum torque [N´m (lb´ft)/rpm]111 (82)/4,200
FuelGasoline

NEW MODEL OUTLINE
MAIN MECHANISM
182CH29
16
4 Features of the 1NZ-FXE engine
1. Highly efficient and high expansion ratio gasoline engine
Adoption of a super fuel-efficient engine developed for use with THS. Its high expansion ratio cycle is achieved by applying the
Atkinson cycle*1 which obtains high thermal efficiency.
2. Reduction in frictional loss
The maximum engine speed is set at 4,500 rpm to reduce frictional resistance, thereby producing a highly efficient low-speed
engine.

An offset crankshaft with 12 mm deviation from the center axis of the cylinder bore is utilized to reduce frictional resistance
of the piston.

Frictional resistance is reduced through the use of low tension valve springs and piston rings.

Lightweight design has been adopted for reciprocating engine parts.
The above measures for reducing frictional loss contribute to improved fuel economy.
3. VVT-i (Variable Valve Timing -intelligent)
The timing of the opening and closing of the intake valves is controlled by the computer according to driving conditions, such
as engine speed and level of acceleration. Thus, smooth intake and exhaust are achieved to greatly improve torque in the low
and medium speed zones. This also contributes to better fuel economy and purification of exhaust gas. Then the VVT-i function
is used to reduce vibration when the engine starts.
4. Compact, lightweight, and low emission
Adoption of an aluminum cylinder block and compact design of parts. And, by positioning the catalytic converter near the engine
for a backwards exhaust layout, we have been able to reduce emissions when the engine is cold started.
*1 : Atkinson Cycle: Proposed by an English engineer named James Atkinson, this thermal cycle enables the compression stroke
and the expansion stroke of the mechanism to be set independently of each other.
Suspension
MacPherson strut type suspension with L-shape
lower arms has been adopted in the front and
torsion beam with toe control link suspension
in the rear. Also, each component part is opti-
mally located and tuned for both excellent con-
trollability and enhanced riding comfort.
EMPS (Electric Motor-assisted Power Steering)
System
Vehicle speed sensing type electric motor-assisted power steering is fitted as standard. Unlike conventional
hydraulic power steering, EMPS does not depend on an engine for its power source, providing a steering feel
in no way inferior to conventional steering when the engine has stopped. Thus it is suitable for the HV system.
Other merits include improved fuel economy through energy conservation, lighter weight, and no need to fill
the power steering fluid.

ENGINE ± 1NZ-FXE ENGINE62
ENGINE CONTROL SYSTEM
1. General
The engine control system for the 1NZ-FXE engine has following system.
System
Outline
SFI
Sequential Multiport
Fuel InjectionAn L-type SFI system directly detects the intake air volume with a hot-wire
type mass air flow meter.
ESA
Electronic Spark
AdvanceIgnition timing is determined by the ECM based on signals from various
sensors. The ECM corrects ignition timing in response to engine knocking.
VVT-i
Variable Valve
Timing-intelligentControls the intake camshaft to an optimal valve timing in accordance with
the engine condition.
ETCS-i
Electronic
Throttle Control
System-intelligentOptimally controls the throttle valve opening in accordance with the ECM,
and the conditions of the engine and the vehicle, and comprehensively
controls the ISC and cruise control system.
Fuel Pump Control
Fuel pump operation is controlled by signal from the ECM.

To stop the fuel pump during operation of the SRS airbag.
Oxygen Sensor Heater
ControlMaintains the temperature of the oxygen sensors at an appropriate level to
increase accuracy of detection of the oxygen concentration in the exhaust gas.
Evaporative Emission
Control

The ECM controls the purge flow of evaporative emissions (HC) in the
charcoal canister in accordance with engine conditions.

Using 3 VSVs and a vapor pressure sensor, the ECM detects any
evaporative emission leakage occurring between the fuel tank and the
charcoal canister, and vapor reducing fuel tank through the changes in the
tank pressure. For details, see page 79.
Toyota HCAC System
The ECM controls the VSV (for Toyota HCAC System) to improve the clean
emission performance of the exhaust gas when the temperature of the TWC
is low. For details, see page 58.
Air Conditioning
Cut-Off ControlBy turning the air conditioning compressor OFF in accordance with the
engine condition, drivability is maintained.
Cooling Fan ControlRadiator cooling fan operation is controlled by signals from ECM based on
the engine coolant temperature sensor signal (THW).
HV Immobiliser
Prohibits fuel delivery, ignition, and starting the HV system if an attempt is
made to start the HV system with an invalid ignition key. For details, see page
80.
DiagnosisWhen the ECM detects a malfunction, the ECM diagnoses and memorizes
the failed section.
Fail-SafeWhen the ECM detects a malfunction, the ECM stops or controls the engine
according to the data already stored in memory.

THS (TOYOTA HYBRID SYSTEM)
THS (TOYOTA HYBRID SYSTEM)
182TH03
Planetary Gear UnitMG1
InverterHV
Battery
MG2
Differential
Gear Unit
Engine
Hybrid Transaxle
Mechanical Power Path
Electrical Path
182TH01
Battery
*
1
Inverter
*
2Engine
Generator Electric Motor
*
1: Direct Current
*2: Alternating Current
182TH02
Battery
Inverter
Engine
Motor / Generator Transmission 22

DESCRIPTION
The hybrid system is a type of powertrain that uses a combination of two types of motive forces, such as an
engine and a motor (MG2). This system is characterized by its skillful use of two types of motive forces ac-
cording to the driving conditions. It maximizes the strengths of each of the motive forces and complements
their weaknesses. Thus, it can achieve a highly responsive, dynamic performance, as well as a dramatic re-
duction in fuel consumption and exhaust gas emissions. The THS can be broadly divided into two systems:
the series hybrid system, and the parallel hybrid system.
± REFERENCE ±
Series Hybrid System
In the series hybrid system, the engine runs a genera-
tor, and the generated electricity enables the electric
motor to drive the wheels. This type of vehicle can be
described as an electric car that is equipped with an
engine-driven generator.
Equipped with a low-output engine, the engine is op-
erated at a practically constant speed in its most ef-
fective range, in order to efficiently recharge the bat-
tery while the vehicle is in motion.
Parallel Hybrid System
This system uses both the engine and the electric mo-
tor to directly drive the wheels is called the parallel
hybrid system. In addition to supplementing the mo-
tive force of the engine, the electric motor in this sys-
tem can also serve as a generator to recharge the bat-
tery while the vehicle is in motion.

CHASSIS ± SUSPENSION AND AXLES
182CH32
Front BushingRear Bushing
A
AFront Bushing
Cross Section
Rear Bushing Cross Section A ± A Cross Section
182CH33
Ball Joint
Stabilizer LinkStabilizer Link
Stabilizer Bar95
Shock Absorber
Low-pressure (N
2) gas sealed shock absorbers that offer stable dampening force characteristics without
causing cavitation have been adopted.
The dampening force characteristics of the shock absorbers have been optimized to achieve excellent
riding comfort, drivability, and stability.
Lower Arm
An L-shaped stamped lower arm has been adopted.
Rubber bushings have been adopted, and the mounting position and the construction of the lower arm
have been optimized to improve the steering feel.
Stabilizer Bar
A ball-joint type stabilizer link has been adopted. Also, by mounting the stabilizer link to the shock absorber,
the excellent stabilizing efficiency has been provided while realizing both steering stability and riding com-
fort.

CHASSIS ± SUSPENSION AND AXLES
165CH48
Center of Bushing
BOUND
Center of Bushing
Camber Change Rate a/L
Camber Change Rate 100%a
L
Instantaneous
Center of
Right Axle
REBOUND
An alignment change that
is very close to that of the
semi-trailing suspension is
effected.
98
Toe and Camber Change
In the torsion beam type suspension, the camber angle and the toe change differ between the same direction
stroke case and the opposite direction stroke case, offering both straightline stability and excellent cornering
stability.
1) Same Direction Stroke Case
Similar to the full-trailing arm type suspension, the axis that joins the center of the right and left trailing
arm bushings is the center of the movement.
2) Opposite Direction Stroke Case
During opposite direction stroke case, or if a difference in suspension travel is created between the right
and left wheels, the torsion beam twists with its shearing center as the center of its rotation.
Also, camber changes in relation to the suspension travel are determined by the ratio of the distance be-
tween the No.1 trailing arm bushing and the axle center and the shearing center (`a' in the Fig. below)
and distance between the No.1 trailing arm bushing and the axle beam (`L' in the Fig. below).
Consequently, through the optimal allocation of the axle beam, the changes in the camber angle in rela-
tion to the suspension travel have been optimized, thus ensuring excellent cornering performance.
Shock Absorber

Low-pressure (N
2) gas sealed shock absorbers that offer stable dampening force characteristics without
causing cavitation have been adopted.

The dampening force characteristics of the shock absorbers have been optimized to achieve excellent
riding comfort, drivability, and stability.

CHASSIS ± BRAKES107
6. Construction and Operation
The brake system of Prius consists of the following components:
Components
Function
Pump and Pump Motor
Draws up the brake fluid from the reservoir tank
and provides high hydraulic pressure to the
accumulator.
Accumulator
Stores the hydraulic pressure that was generated
by the pump. The accumulator is filled with
highpressure nitrogen gas.
Power
Supply
PortionPressure Switches
Monitors the hydraulic pressure of the
accumulator and outputs control signals for the
pump motor.
There are two types: the pressure switch PH for
controlling the pump, and the pressure switch PL
for giving a warning when the pressure is low.
Hydraulic
Brake
Booster
Relief Valve
Returns the brake fluid to the reservoir tank to
prevent excessive pressure if the pump operates
continuously due to a malfunction of the pressure
switch.
Reservoir TankStores the brake fluid.
Brake Fluid Level
Warning SwitchDetects the low brake fluid level.
Master
Master Cylinder
Generates the hydraulic pressure in accordance
with the pedal effort that is applied to the brake
pedal.
Master
Cylinder
Portion
Brake Booster
Regulates the accumulator pressure in accordance
with the pedal effort that is applied to the brake
pedal and introduces this pressure to the boosterBrake Boosterpedal and introduces this pressure to the booster
chamber in order to provide a power assist to the
brakes.
Pressure SensorsDetects the pressure of the master cylinder,
regulator, and front and rear wheel cylinders.
Switching
Solenoid ValvesSwitches the hydraulic path between normal
braking and braking under control.
Brake
Actuator
ABS Control Solenoid
Valves
Pressure Holding
Valves
Pressure Reduction
Valves
Controls the hydraulic pressure that is applied to
the wheel cylinders during ABS control or EBD
control.
Actuator
Linear Solenoid Valve
Regulates the hydraulic pressure to the wheel
cylinders during braking in accordance with the
fluctuations in the regenerative brake force.
Reservoir
Temporarily stores the brake fluid when
regulating the hydraulic pressure to the wheel
cylinders in accordance with the fluctuations in
the regenerative brake force.
Stroke SimulatorGenerates a pedal stroke during braking in
accordance with the driver's pedal effort.

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 ELECTRICAL ± AIR CONDITIONING
163BE17
Inner FinAntibacterial Agent
Nylon Layer
Chromate Layer
Aluminum
Matrix
182BE48
ModulatorMulti-Flow Condenser
Condensing Portion
Gaseous Refrigerant
Liquid Refrigerant
Super-Cooling Portion 158
Evaporator
By placing the tanks at the top and the bottom of the evaporator unit and by adopting an inner fin construc-
tion, the heat exchanging efficiency has been improved and the evaporator unit's temperature distribution
has been made more uniform. As a result, it has become possible to realize a thinner evaporator construction.
Furthermore, the evaporator body has been coated with a type of resin that contains an antibacterial agent
in order to minimize the source of foul odor and the propagation of bacteria.
2. Condenser
The Prius has adopted sub-cool condenser in which a multi-flow condenser (consisting of two cooling por-
tions: a condensing portion and a super-cooling portion) and a gas-liquid separator (modulator) have been
integrated. This condenser has adopted the sub-cool cycle for its cooling cycle system to improve the heat
exchanging efficiency.
This condenser is integrated with the radiator to minimize the space they occupy in the engine compartment.
For details, see page 54 in the Engine Cooling System Section.
Sub-Cool Cycle
In the sub-cool cycle of the sub-cool condenser that has been adopted, after the refrigerant passes through
the condensing portion of the condenser, both the liquid refrigerant and the gaseous refrigerant that could
not be liquefied are cooled again in the super-cooling portion. Thus, the refrigerant is sent to the evaporator
in an almost completely liquefied state.

BODY ELECTRICAL ± AIR CONDITIONING
165BE24
Condenser and Modulator
Scroll Compressor
with Oil Separator
Separator
Compressor Refrigerant Gas +
Compressor Oil
Compressor Oil
Evaporator Expansion
Valve 162
Oil Separator
1) General
A CS (Centrifugal with Shutter) type oil separator has been adopted to reduce the circulation rate of the
compressor oil that is intermixed with the refrigerant and circulates in the refrigeration cycle.
This oil separator is provided with a cylindrical pipe in the separator case, enabling the refrigerant gas
that has been discharged through the discharge gas inlet to be separated into refrigerant gas and oil
through centrifugal force, and minimizing the outflow of the oil to the discharge service port. As a result,
the oil circulation rate has been reduced and makes energy savings possible.