steering TOYOTA PRIUS 2001 Service User Guide

2001 PRIUS (EWD414U)
M OVERALL ELECTRICAL WIRING DIAGRAM
1
234
21 PRIUS
2ACC
IG1
ST1
IG2
ST2 AM1
7AM2
1
120A MAIN
1B 1C
1D2H 1
5A AM1
2B 3
ID Co wl s id e
panel LH2K 8
1B 215A
AM2 1J 92C 2
2G 1
A
W±B W± B W± GW
W±R B
WB±G
W±R W± G
I15
IGNITION SW
100 A DC/ DCBATTERYF18
FUSI BLE L I NK
BLOCK NO. 2F11 F12,
FUSIBLE LINK
BL OCK NO. 1BCF13, DSI L TC 5B 12B 19B 6B12C9C7C10C
12
SPI RAL
CA BLE
21
2 1 14 B 13 B 10 B 11 B 9 B 20 B
21 15 B 26 B
B± W
IG2
Y±R
Y
Y± B
A17 A1 8,
AI RBAG SENSOR ASSEMBLYAB
Y± G B± W BR±WW±RBR
F 2
FRONT AIRBAG
S ENSOR RH A21
AI RBAG SQUI B
(
Steering Wheel
Pad)A20
AI RBAG SQUI B
(
Front Passenger
Airbag As sembly)
F 1
FRONT AI RBAG
SENSOR LH±SL +SL ±SR +SR P± P+ D± D+
GR
LG
L±Y
PESR SSR± SSR+ VUPR ACC
3IL1 4IL1 1IL1 2IL1
BR±WW±RBR
GR W P±B
A19 , C
B±O
To Data Link Connector 3
<2±5><2±6>
2 1 6A 5AY±R Y± GS 6
SIDE AIRBAG
SQUIB LHSFL± SFL+
C 2C 1
21
Y± GY±RS 7
S I DE AI RBA G
SQUIB RHSFR+ SFR± 2E 3
C 5C 6
21
Y± BYP15
PRETENSIONER
RHPR± PR+
W± BPL+ PL±
P14
PRETENSIONER
LH
Y
Y± BA
1 21 2A4 3 2 1 123
7A 10A 12A 9A4
GR± L
LG±B
L±W
P±LESL SSL± SSL+ VUPR 3B
LA
B±Y2E 12A 9 2B 4
B±YL
W P± B
2B 5
2E 2B± W
10A ACC
2D 2
2 1
3 5 2C 8
10 A SRS ACC
2E 4
GR± R
P±L
6
B± W
3
P±L
ACC RELAY
S 4
SI DE AI RBAG SENSOR L HS 5
S I DE A I RBA G SE NSOR RH
SRS Power Source
C
B C
A5
B14
A
16 A
LBE+8To Buckle SW LH
< 9±3>
RBE+23 B
LGSW2To Hy brid Vehicle
Con t r ol ECU< 1 ±20 >
11
From Buckle SW RH
<9±3>
G±O
AC
G±O
GR± R BB
GR ±R
J26
JUNCTI ON
CONNECTOR
C10 C1 1,
SRS WARNI NG LI GHT
[COMB. METER]AB J27 J28,
JUNCTION
CONNECTORAB* 1 : w/ Side Air bags
(
*1) (
*1) (
*1) (
*1) (
*1) (
*1) (
*1) (
*1)
(
*1) (
*1) (
*1) (
*1)
28 B
E2
J11
JUNCTI ON
CONNECTOR
Right kick
panel
W±BIHB 27E1W±B
2A 7
2B 6 LLBR

MODEL CODE AND MODEL LINE-UP
3
MODEL CODE
NHW11 L ± A E E E B A
12345678
1BASIC MODEL CODE1NHW11: With 1NZ-FXE Engine
2STEERING WHEEL POSITION2L: Left-Hand Drive
3MODEL NAME3A: Prius
4BODY TYPE4E: 4-Door Sedan
5GEAR SHIFT TYPE5E: Automatic, Column
6GRADE6E: Standard
7ENGINE SPECIFICATION7B: Atkinson
DESTINATION
8A: U.S.A.
K: Canada
MODEL LINE-UP
TRANSAXLE
DESTINATIONENGINEBODY
TYPEGRADEAutomaticTYPE
P111
U.S.A.
1NZ FXESedanStandard
NHW11L-AEEEBA
Canada1NZ-FXESedanStandardNHW11L-AEEEBK

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.

CHASSIS ± SUSPENSION AND AXLES
182CH30
181CH22
King Pin Axis
Axle Center
Front93
2. Front Suspension
General
A MacPherson strut type independent suspension with an L-shaped lower arm has been adopted. Through
the optimal allocation of components, and the adoption of the nachlauf geometry, negative camber, and anti-
dive geometry, the front suspension realizes excellent riding comfort, stability, and controllability.
Nachlauf Geometry
The front suspension adopts the nachlauf geome-
try in which the king pin axis is located ahead of
the axle center.
As a result, excellent straightline stability has
been realized and the steering feeling has been
improved.

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
NOTICE
Be sure to use the jack-up points that are provided on the body when raising the vehicle on a jack. Never
apply a jack under the axle beam, training arm, or the bushing of the rear suspension.
182CH34
Never use these areas
as jack-up points. 96
3. Rear Suspension
General

A torsion beam type suspension with toe control links has been adopted, in which an axle beam is located
in the middle of the trailing arm.

The torsion beam type rear suspension minimizing change in the tire-to-road camber during cornering,
thus delivering good cornering stability and driving stability.

The stabilizer bar has been adopted to realize excellent drivability and stability.

A toe control link mechanism has been adopted in the construction of the trailing arm bushings. The toe-
correct function that is effected by the movement of the links results in optimal compliance steering, thus
achieving excellent drivability, stability, and riding comfort at high levels.

CHASSIS ± STEERING
182CH62
122
STEERING
DESCRIPTION
A vehicle-speed sensing type EMPS (Electric Motor-assisted Power Steering) has been adopted. The
EMPS uses the EMPS ECU to control a DC motor that is mounted on the steering gear in accordance with
the signals received from various sensors to provide power assist to the steering effort.
A rack and pinion type steering gear and a stepless tilt steering have been adopted.
The steering column has adopted an energy absorbing mechanism that uses energy absorbing plate.

Specifications 
Gear Ratio (Overall)16.4
18.3
No. of Turns Lock to Lock3.99
Rack Stroke mm (in.)149.6 (5.89)

CHASSIS ± STEERING
182CH68
Rear Wheel
Speed SensorsBrake ECU
Torque Sensor Signal 1
Torque Sensor Signal 2
EMPS
ECUMeter ECU
Gateway ECUDLC3
Display ECU
Multi-information
Display
123
EMPS (Electric Motor-assisted Power Steering)
1. General
In accordance with sensor information such as that provided by the rear wheel speed sensors, the torque sen-
sor that is mounted on the steering gear, and the EMPS ECU determines the direction and the force of the
power assist and actuates the DC motor that is mounted on the steering gear to provide power assist to the
steering effort.
The EMPS in the Prius the following features:
This system can provide power assist even when the engine is stopped.
This system offers excellent fuel economy characteristics because power assist is provided by the DC mo-
tor that is mounted on the steering gear, and this motor consumes energy only when power assist is re-
quired.
Unlike the conventional hydraulic power steering system, this system excels in serviceability because it
does not require pipes or the power steering fluid.

System Diagram 

CHASSIS ± STEERING
182CH69
Meter ECU
EMPS ECU
Relay
DC MotorRear Wheel Speed
Sensors and Rotors
Brake ECU Multi-information Display 124
2. Layout of Main Components
3. Function of Main Components
ComponentsFunction
St i
Torque Sensor
Detects the twist of the torsion bar, converts the torque that is applied
to the torsion bar into an electrical signal, and outputs this signal to
the ECU.
Steering
Gear
DC MotorGenerates power assist in accordance with a signal received from the
EMPS ECU.
Reduction
MechanismReduces the rotation of the DC motor and transmits it to the pinion
shaft.
EMPS ECU
Actuates the DC motor mounted on the steering gear for providing
power assist, based on the signals received from various sensors and
the rear wheel speed signal.
Meter ECUOutputs a signal for displaying the PS warning on the center display
in case of a malfunction in the system.
Brake ECURear wheel speed signals are outputted to EMPS ECU.
RelaySupplies power to the DC motor for power assist.
Multi-information DisplayDisplays the PS warning in case of a malfunction in the system.

CHASSIS ± STEERING
182CH70
182CH71
182CH72
Torque
Sensor
Rack and
PinionDC Motor
Reduction Mechanism
Motor
Shaft
Stator
Rotor
Pinion Gear
Motor Shaft
DC Motor
Ring Gear
Pinion Shaft125
4. Construction and Operation of Main Components
Steering Gear
1) General
The steering gear consists of the rack and pin-
ion, DC motor, reduction mechanism, and
torque sensor. The front suspension compo-
nents have been optimized to reduce the load
on the DC motor. Also, the components have
been optimally allocated to ensure ample rack
travel and wheel turning angle, resulting in
excellent cornering performance.
2) DC Motor
The DC motor is mounted on the gear hous-
ing. The DC motor consists of the motor shaft
that is integrated with the hypoid pinion to
transmit the torque that has been generated by
the drive force of DC motor to the pinion
shaft, the rotor and stator.
3) Reduction Mechanism
A reduction mechanism that transmits the
rotation of the motor to the pinion shaft has
been mounted on the steering gear. The reduc-
tion mechanism consists of the ring gear that
is secured to the pinion shaft and the pinion
gear that is integrated with the motor shaft.
The power assist of the motor is transmitted
by the reduction mechanism to the pinion
shaft, which provides power assist to the
steering effort.