2001 TOYOTA PRIUS AUX

THS (TOYOTA HYBRID SYSTEM) 24

MAIN FUNCTIONS OF COMPONENTS
MG1Generates high-voltage electricity by being powered primarily by the engine.
Also functions as a starter to start the engine.
Hybrid
Trans-
axle
MG2
Primarily provide additional power to the engine in order to increase the
overall drive force. During braking, or when the accelerator pedal is not
depressed, it generates electricity to recharge the HV battery (Regenerative
brake system).
Planetary
Gear UnitDistributes the engine's drive force as appropriate to directly drive the vehicle
as well as the generator.
HV Battery
Supplies electric power to the MG2 during start-off, acceleration, and uphill
driving; recharged during braking or when the accelerator pedal is not
depressed.
InverterA device that converts the high-voltage DC (HV battery) into AC (MG1 and
MG2) and vice versa (Converts AC into DC).
Converter
Drops the high-voltage direct current (DC 273.6 V) into DC12 V in order to
supply electricity to body electrical components, as well as to recharge the
auxiliary battery (12 V).
HV (Hybrid Vehicle
Control) ECU
Information from each sensor as well as from the ECU (ECM, Battery ECU,
ABS ECU) is received, and based on this the required torque and output power
is calculated.
The HV ECU sends the calculated result to the actuators and controllers.
ECMSends a throttle open command to the electronically-controlled throttle in
accordance with the engine output request factor received from the HV ECU.
Battery ECUMonitors the charging condition of the HV battery.
Brake ECU
Controls the regenerative brake that is effected by the MG2 and the hydraulic
brake so that the total braking force equals that of a conventional vehicle that
is equipped only with hydraulic brakes.
Also, the brake ECU performs the ABS control conventionally.
Accelerator PedalConverts the accelerator angle into an electrical signal and outputs it to the HVAccelerator Pedal
Position Sensor
Converts the accelerator angle into an electrical signal and outputs it to the HV
ECU.
Shift Position SensorConverts the shift lever position into an electrical signal and outputs it to the
HV ECU.
SMR (System Main
Relay)Connects and disconnects the high-voltage power circuit through the use of
a signal from the HV ECU.
Service plugShuts off the high-voltage circuit of the HV battery when this plug is removed
for vehicle inspection or maintenance.

THS (TOYOTA HYBRID SYSTEM)
Shift Position
Sensor
182TH05
Accelerator
Pedal Position
Sensor
BRAKE
ECU
Shift Position
(Main and Sub)
Accelerator Angle
(Main and Sub)
Regenerative
Request FactorHV ECUInverter
Voltage
SMR Control
MG2MG1
RPMEngine
Power
RequestCharging
Condition,
Amperage
SMRSMR
Amperage
HV
Battery Engine
Planetary Gear
Unit
Wheel
Wheel
ECM
Battery
ECU
Hydraulic
Brake
Actual
Regenerative
Braking Factor
Auxiliary
Battery
Mechanical Power Path
Electrical Signal Hydraulic
Converter
25

SYSTEM DIAGRAM

THS (TOYOTA HYBRID SYSTEM)
M-UU,
VU, WU
M-SDOWN
G-UU,
VU, WU
CONT 3
SENSORS ACTUATORS
INVERTER (for MG1)
INVERTER (for MG2)
G-SDOWN
DATA LINK CONNECTOR 3 SIL, TC
IGCT RELAYAUXILIARY
BATTERY MRELBATT
BATTERY ECU
ABS ECU
VEHICLE SPEED SIGNAL
(for Hybrid Transaxle)
ACCELERATOR PEDAL
POSITION SENSOR
SHIFT POSITION SENSOR
CRUISE CONTROL SWITCH
AIRBAG SENSOR ASSEMBLY
CIRCUIT BREAKER SENSOR
INTERLOCK SWITCH
(for Inverter Cover and Service Plug)
STOP LIGHT SWITCH
A / C ECU
CONVERTER NODD
MG2
M-REF,
SIN, COS
MG1
G-REF,
SIN, COS
ECM
COMBINATION METER

Vehicle Speed Signal SPD
INVERTER
(for MG1)
INVERTER
(for MG2)
CONT 2
SYSTEM MAIN RELAY NO.1
SYSTEM MAIN RELAY NO.2
SYSTEM MAIN RELAY NO.3
G-MOTT
M-MOTT
CONT 1
HV ECU
HTD, DTH
HTB, BTH
VPA1, 2
SFT, P, R,
N, D, B
CCS
ABFCS
ACS
ILK
STP EGON
HTE, ETH
ACON
G-INVT
G-IU, IV, IW
M-SINV, FINV
M-INVT
M-IU, IV, IW
GO
SPDO
ESTP
IB
G-SINV, FINV
MG1
MG2
28
2. Construction
The configuration of the THS control system in the Prius is shown in the following chart.

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.

THS (TOYOTA HYBRID SYSTEM)
182TH26
Inverter
Converter
182TH17
F. L
MAINF.L DCDC12 V

Output
Auxiliary
Battery S34B20
Shielded 12 VInverter
SDC273.6 V
DC / DC Converter
Input Filter
20 V
Converter Control Circuit
HV ECU A / C ECUIG
IDH NODD 36
CONVERTER
1. General
The power source for auxiliary equipment of the
vehicle such as the lights, audio system, and the air
conditioner cooling fan, as well as the ECUs, is
based on a 12 V system. Because the THS genera-
tor outputs at 273.6 V, the converter is used to
transform the voltage from DC273.6 V to DC 12
V in order to recharge the auxiliary battery. The
converter is installed on the underside of the in-
verter.
2. Operation

The DC273.6 V input is initially converted into alternating current by the transistor bridge circuit and
transformed into a low voltage by the transformer. After this, the current is rectified, smoothed (into direct
current) and converted into DC12 V.

The voltage at the positive terminal of the auxiliary battery is monitored by the converter and is maintained
at a constant level. Consequently, the voltage of the auxiliary battery is unrelated to the engine rpm (even
if the engine is stopped) and to the auxiliary equipment (output current of converter).

THS (TOYOTA HYBRID SYSTEM)
182TH21
Lead-calcium Alloy 42
AUXILIARY BATTERY
DESCRIPTION
The shielded, maintenance-free 12V battery (S34B20L) for the Prius is used.
Battery fluid is filtered into separators in order to reduce hydrogen gas released which occurs when the battery
is charged.
Therefore, battery fluid does not need to be replaced, as long as the specified battery is used.
HV IMMOBILISER SYSTEM
The HV immobiliser system has been designed to prevent the vehicle from being stolen. This system uses a
ECM 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 ECM prohibit fuel delivery and ignition, effectively disabling the engine.

BODY ELECTRICAL
BODY ELECTRICAL ± BATTERY AND MULTIPLEX COMMUNICATION SYSTEM
182BE01
: BEAN : UART
: AVC-LAN : Serial Data
Link
Brake ECU
HV ECU
Air Condi-
tioning ECU
Meter ECU
ECM
Body ECU
Display ECU
Audio
ComponentsGateway
ECU
Power Window
Master SwitchDoor Con-
trol ReceiverBattery ECU
141
AUXILIARY BATTERY
DESCRIPTION
All the body electrical systems and auxiliary equipment operate using the same 12 V battery used on ordinary
gasoline engine vehicles.
However, as the battery structure is different, Prius uses an exclusive battery. See page 42 in the THS (TOYOTA
Hybrid System) section for details of the auxiliary battery structure.
MULTIPLEX COMMUNICATION SYSTEM
DESCRIPTION
A multiplex communication system has been adopted for body electrical system control and to achieve
a slimmer wiring harnesses configuration.
BEAN (Body Electronics Area Network) has been adopted between the body ECU, ECM, meter ECU,
air conditioning ECU, and the gateway ECU. Furthermore, AVC-LAN (Audio Visual Communication-
Local Area Network) has been adopted between the display ECU and the audio components.
The conversion of communication signals between BEAN and AVC-LAN is performed by the gateway
ECU.
UART (Universal Asynchronous Receiver Transmitter), which performs unidirectional communication,
has been adopted between the body ECU and the power window master switch.
A serial data link has been adopted between the body ECU and the door control receiver. In addition, a
serial data link has been adopted between the ECM, HV ECU, brake ECU, and the battery ECU, which
pertain to the control of the hybrid system.

System Diagram 

B04748
B04749
1. +Terminal
2. +Terminal3. ±Terminal
4. ±Terminal
B04750
± INTRODUCTIONFOR ALL OF VEHICLES
IN±13
13 Author: Date:
2001 PRIUS (RM778U)
2. PRECAUTIONS TO BE OBSERVED WHEN INSPECT-
ING OR SERVICING ENGINE COMPARTMENT
The PRIUS, automatically turns the engine ON and OFF when
the ignition switch is set to the ON position provided that the
READY light on the instrument panel is it.
Before inspecting or servicing the engine compartment, there-
fore, remove the ignition switch key.
3. ACTIONS TO BE TAKEN WHEN BATTERIES ARE DE-
PLETED
(a) Actions to be taken when the auxiliary battery is depleted
HINT:
The following phenomena indicate that the auxiliary battery is
depleted:

No display appears on the instrument panel when you
turn the ignition switch to the ON position.

The hybrid system does not start.

The headlights are dark.

The sound from the horn is weak.
NOTICE:
Never use a quick charger.
(1) Move the shift lever to the P position, and engage
the parking brake.
(2) Remove the ignition key plate from the ignition
switch.
(3) Using a booster cable, connect the 12 V battery of
the rescue vehicle and auxiliary battery of the
stalled vehicle, as shown in the illustration.
(4) Start the engine of the rescue vehicle and run the
engine at a speed slightly higher than the idling
speed for 5 minutes to charge the auxiliary battery
of the stalled vehicle.
(5) Turn the ignition switch of the stalled vehicle to the
START position to start the hybrid system.
If the hybrid system fails to start and the master and HV battery
warning lights come on, the HV battery may have been dis-
charged.
(6) Disconnect the booster cable in the reverse way of
the connection procedure.
NOTICE:
If the auxiliary battery needs to be replaced, replace it only
with a 12 V battery specially designed for the use of the
PRIUS.