2001 TOYOTA PRIUS ABS

THS (TOYOTA HYBRID SYSTEM)
182TH33
31
± REFERENCE ±
The MG1 and the MG2 are generally shut down when the shift lever is in the N position.
However, the shut-down function is canceled under the following exceptions:

During driving, if the brake pedal is depressed and a wheel locks up, the ABS is activated. After this, low
torque is requested from the MG2 to provide supplemental power in order to restart the rotation of the wheel.
Even if the shift lever is in the N position at this time, the shut-down function is canceled to allow the wheel
to rotate. After the wheel rotation has been restarted, the system resumes its shut-down function.

When the vehicle is driven in the D or B position and the brake pedal is depressed, the regenerative brake
operates. At this time, as the driver moves the shift lever to the N position, the brake hydraulic pressure in-
creases while the request torque of the regenerative brake decreases gradually so as not to create a sluggish
brake feel. After this, the system effects its shut-down function.
When any of the conditions described below is pres-
ent, the message prompt as shown appears in the
multi information display, accompanied by the illu-
mination of the master warning light and the continu-
ous sounding of the buzzer.

The ªREADYº light is illuminated, the shift lever
is in the N position, and the HV battery is dis-
charged.

The ªREADYº light is illuminated, the shift lever
is in the N position, and the driver's door is open.

The ªREADYº light is illuminated, the parking brake is engaged, the shift lever is in the B or D position, and
the driver's door is open.

THS (TOYOTA HYBRID SYSTEM)
182TH29
Rotational
Magnetic FieldU PhaseStator Coil
Rotor
Repulsion
W Phase V Phase
: From inverter
: Connected internally in the motor
Attruction
182TH09
Magnetized Side
Coil A
Coil B
Coil C Speed Sensor
(Resolver)Output Side
182TH10
Inverter Power Cable HV Battery
Junction
BlockPortion routed through
the center floorAuxiliary
Battery
Under-
the-Floor
Reinforcement
12 V
Power Cable
Voltage 
Power Cable
Voltage

34
1. Permanent Magnet Motor
When a three-phase alternating current is passed
through the three-phase windings of the stator
coil, a rotational magnetic field is created in the
electric motor. By controlling this rotating mag-
netic field according to the rotor's rotational posi-
tion and speed, the permanent magnets that are
provided in the rotor become attracted by the ro-
tating magnetic field, thus generating torque.
The generated torque is for all practical purposes
proportionate to the amount of current, and the
rotational speed is controlled by the frequency of
the alternating current.
Furthermore, a high level of torque, all the way to
high speeds, can be generated efficiently by prop-
erly controlling the rotating magnetic field and the
angles of the rotor magnets.
2. Speed Sensor (Resolver)
This is an extremely reliable and compact sensor
that precisely detects the magnetic pole position,
which is indispensable for ensuring the efficient
control of MG1 and MG2.
The sensor's stator contains 3 coils as illustrated, and
output coils B and C are electrically staggered 90 de-
grees. Because the rotor is oval, the distance of the
gap between the stator and the rotor varies with the
rotation of the rotor. Thus, by passing an alternating
current through coil A, output that corresponds to the
sensor rotor's position is generated by coils B and C.
The absolute position can then be detected from the
difference between these outputs.
In addition, the amount of positional variance
within a predetermined time is calculated by the
HV ECU, thus enabling this sensor to be used as
an rpm sensor.
3. Power Cable
The power cable is a high-voltage, high-amperage
cable that connects the HV battery with the inverter,
and the inverter with MG1 and MG2. Starting from
the connector at the left front of the HV battery lo-
cated in the luggage compartment, the power cable
is routed under the rear seat, through the floor panel,
along the under-the-floor reinforcement, and con-
nects to the inverter in the engine compartment. A
shielded cable is used for the power cable in order to
reduce electromagnetic interference.
The 12 V  wiring of the auxiliary battery also
follows the same route.
For identification purposes, the high-voltage wir-
ing harness and connectors are color-coded
orange to distinguish them from those of the ordi-
nary low-voltage wiring.

CHASSIS ± P111 HYBRID TRANSAXLE
182CH02
Power Splitting Device
Transaxle
Damper
MG2
Sun Gear
Carrier
Ring GearMG1
Oil Pump
Silent ChainEngine
Counter Gears
Final Gears
182CH03
Coil Spring
Drive force
from the
engine 80
TRANSAXLE UNIT
1. General
The transaxle unit consists primarily of a transaxle damper, MG (Motor Generator) 1, MG2, power splitting
device and a reduction unit (containing a silent chain, counter gears, and final gears).
2. Transaxle Damper

A coil-spring type damper with low-twist char-
acteristics has been adopted as the mechanism
to transmit the drive force from the engine.

A torque fluctuation absorbing mechanism that
uses a dry-type single-plate friction material
has been adopted.

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 ± SUSPENSION AND AXLES
182CH36
12-point Nut
Double-Row Angular
Ball Bearing
182CH37
ABS Speed Sensor
Double-Row
Angular Ball
Bearing99
AXLES
1. Front Axle

The front axle use a double-row angular ball bearing which offers low rolling resistance.

A lock nut (12-point) has been adopted and staked for tightening the axle hub in order to ensure the tighten-
ing performance. This nut cannot be reused.
2. Rear Axle

The rear axle use a double-row angular ball
bearing which offers low rolling resistance.

ABS speed sensor and rotor are built in the axle
bearing.

CHASSIS ± BRAKES
182CH38
100
BRAKES
DESCRIPTION
The front brakes use ventilated disc brakes and the rear brakes use leading-trailing drum brakes.
To adjust the clearance between the shoes and drum, the rear drum brakes uses the incremental type hy-
draulic auto adjuster.
On the Prius uses a pedal type parking brake that is released by pressing the pedal further.
A hydraulic brake booster in which the master cylinder and booster are integrated has been adopted.
The Prius has adopted the ABS with EBD (Electronic Brake force Distribution) as a standard equipment.
A regenerative brake system, which uses the MG2 that is used for driving the vehicle as a generator to
efficiently convert the energy that is created during braking has been adopted. This system enables to col-
lect more driving energy by having the control to cooperate the hydraulic brake and the regenerative brake.

CHASSIS ± BRAKES
182CH39
182CH40
101

Specifications 
Master CylinderTypeSingleMaster CylinderDiameter mm (in.)22.22 (0.87)
Brake Booster TypeHydraulic
TypeVentilated Disc
Front BrakeCaliper TypePE54Front BrakeWheel Cylinder Dia. mm (in.)54.0 (2.13)
Rotor Size (D x T)* mm (in.)255 x 22 (10.04 x 0.87)
TypeLeading-Trailing Drum
Rear BrakeWheel Cylinder Dia. mm (in.)20.64 (0.81)
Drum Inner Dia. mm (in.)200 (7.87)
Brake Control Valve TypeP & B Valve
TypeDrum
Parking BrakeSize mm (in.)200 (7.87)g
Lever TypePedal
ABS with EBDSTD
*: D: Outer Diameter, T: Thickness
FRONT BRAKE
The PE54 type brake calipers and ventilated disc
rotor have been adopted. These brake calipers are
lightweight and compact to realize excellent brake
performance.
REAR BRAKE
General
The leading-trailing type drum brakes using
drums with a 200 mm (7.87 in.) inner diameter
have been adopted.
A hydraulic system that adjusts the clearance
between the shoes and the drum has been
adopted.