troubleshooting TOYOTA PRIUS 2001 Service Repair Manual

2001 PRIUS (EWD414U)
A INTRODUCTION
This manual consists of the following 13 sections:
No.
SectionDescription
A
INDEXIndex of the contents of this manual.
A
INTRODUCTIONBrief explanation of each section.
BHOW TO USE THIS
MANUALInstructions on how to use this manual.
CTROUBLE±
SHOOTINGDescribes the basic inspection procedures for electrical circuits.
DABBREVIATIONSDefines the abbreviations used in this manual.
E
GLOSSARY OF
TERMS AND
SYMBOLS
Defines the symbols and functions of major parts.
FRELAY LOCATIONSShows position of the Electronic Control Unit, Relays, Relay Block, etc.
This section is closely related to the system circuit.
GELECTRICAL
WIRING ROUTINGDescribes position of Parts Connectors, Splice points, Ground points, etc.
This section is closely related to the system circuit.
INDEXIndex of the system circuits.
H
SYSTEM CIRCUITS
Electrical circuits of each system are shown from the power supply through ground
points. Wiring connections and their positions are shown and classified by code
according to the connection method. (Refer to the section, ºHow to use this manualº).
The ºSystem Outlineº and ºService Hintsº useful for troubleshooting are also contained
in this section.
IGROUND POINTShows ground positions of all parts described in this manual.
JPOWER SOURCE
(Current Flow Chart)Describes power distribution from the power supply to various electrical loads.
KCONNECTOR LISTDescribes the form of the connectors for the parts appeared in this book.
This section is closely related to the system circuit.
LPART NUMBER OF
CONNECTORSIndicates the part number of the connectors used in this manual.
M
OVERALL
ELECTRICAL
WIRING DIAGRAM
Provides circuit diagrams showing the circuit connections.

2001 PRIUS (EWD414U)
HOW TO USE THIS MANUAL B
This manual provides information on the electrical circuits installed on vehicles by
dividing them into a circuit for each system.
The actual wiring of each system circuit is shown from the point where the power
source is received from the battery as far as each ground point. (All circuit
diagrams are shown with the switches in the OFF position.)
When troubleshooting any problem, first understand the operation of the circuit
where the problem was detected (see System Circuit section), the power source
supplying power to that circuit (see Power Source section), and the ground points
(see Ground Point section). See the System Outline to understand the circuit
operation.
When the circuit operation is understood, begin troubleshooting of the problem
circuit to isolate the cause. Use Relay Location and Electrical Wiring Routing
sections to find each part, junction block and wiring harness connectors, wiring
harness and wiring harness connectors, splice points, and ground points of each
system circuit. Internal wiring for each junction block is also provided for better
understanding of connection within a junction block.
Wiring related to each system is indicated in each system circuit by arrows
(from__, to__). When overall connections are required, see the Overall Electrical
Wiring Diagram at the end of this manual.

2001 PRIUS (EWD414U)
B
[O]: Explains the system outline.
[P]: Indicates values or explains the function for reference during troubleshooting.
[Q]: Indicates the reference page showing the position on the vehicle of the parts in the system circuit.
Example : Part ºL4º (Light Failure Sensor) is on page 36 of the manual.
*The letter in the code is from the first letter of the part, and the number indicates its order in parts
starting with that letter.
Example : L 4 Parts is 4th in order
Light Failure Sensor
[R]: Indicates the reference page showing the position on the vehicle of Relay Block Connectors in the system circuit.
Example : Connector º1º is described on page 18 of this manual and is installed on the left side of the instrument
panel.
[S]: Indicates the reference page showing the position on the vehicle of J/B and Wire Harness in the system circuit.
Example : Connector º3Cº connects the Instrument Panel Wire and J/B No.3. It is described on page 22 of this
manual, and is installed on the instrument panel left side.
[T]: Indicates the reference page describing the wiring harness and wiring harness connector (the female wiring
harness is shown first, followed by the male wiring harness).
Example : Connector ºIE1º connects the floor wire (female) and Instrument panel wire (male). It is described on
page 42 of this manual, and is installed on the left side kick panel.
[U]: Indicates the reference page showing the position of the ground points on the vehicle.
Example : Ground point ºBOº is described on page 50 of this manual and is installed on the back panel center.
[V]: Indicates the reference page showing the position of the splice points on the vehicle.
Example : Splice point ºI5º is on the Cowl Wire Harness and is described on page 44 of this manual.

2001 PRIUS (EWD414U)
B HOW TO USE THIS MANUAL
The ground points circuit diagram shows the connections from all major parts to the respective ground points. When
troubleshooting a faulty ground point, checking the system circuits which use a common ground may help you identify
the problem ground quickly. The relationship between ground points (
EA, IB and IC shown below) can also be
checked this way.

I GROUND POINT
FAN MAIN RELAY
FAN MAIN RELAY
A/C FAN RELAY NO.2
A/C FAN RELAY NO.3
RADIATOR FAN MOTOR
RETRACT CONTROL
RELAY
RETRACT MOTOR RH
RETRACT MOTOR LH
FRONT TURN SIGNAL
LIGHT RH
PARKING LIGHT RH
FRONT TURN SIGNAL
LIGHT LH
PARKING LIGHT LH
DOOR LOCK CONTROL
SW RH
DOOR KEY LOCK
SW RH
DOOR LOCK MOTOR
RH
BLOWER RESISTOR
A/C AMPLIFIER
RADIO AND PLAYER
HEATER RELAY
AUTO ANTENNA
MOTOR
BLOWER SW
PARKING BRAKE SW
COMBINATION METER
HORN SW [COMB. SW]
TURN SIGNAL FLASHER
DOOR KEY LOCK SW LH
DOOR LOCK MOTOR LH
FUEL CONTROL SW
WOOFER AMPLIFIER
COMBINATION METER
COMBINATION METER
FUEL SENDER
CIGARETTE LIGHTER
O/D MAIN SW
CLOCK
5
5
5
5
4
4
4
4
4BA15
IB18
EA2 10
3E5
3E
6 3G
13 3F
3 3D
1 3B
7
ID115
IC33
IA12
E 3
A
A AW±B
W±BW±B W±B
W±B W±B
W±B
W±B
W±B
W±B
W±B
W±B
W±B
W±B
W±B W±BW±B W±B W±B W±B
W±B W±B
W±BW±B
W±B
W±B
W±B W±B
W±B
BR
W±B
BR BRW±BW±B
W±B
W±B
W±B
W±B
W±B
W±B
W±B
W±B
W±B W±B
W±B
W±B
W±B
W±B
BR W±B
BR BR
BR W±B W±BW±B
W±BW±BBR W±B (4A±GZE)
W±B A A A
I 6
I 6
I 2
I 2
I 2
B 5I 5
I 5
I 5
B 5
B 5
B 5
I 5
I 5
I 3I 3
E 3
E 3
E 3
E 2
E 4
E 5
E 4
E 5
E 6E 4
E 4
B 4
EAI 4
B 4
B 4
I 4I 8
IBIC
3C7
4
JUNCTION
CONNECTOR J 1
4
DOOR LOCK CONTROL
RELAY
ELECTRICAL IDLE-UP
CUT RELAY (M/T)FRONT SIDE MARKER
LIGHT RH
FRONT SIDE MARKER
LIGHT LH
BRAKE FLUID LEVEL
WARNING SW
UNLOCK WARNING
SW WIPER AND WASHER
SW [COMB. SW] LIGHT CONTROL SW
[COMB. SW] HEATER CONTROL
ASSEMBLY
HEATER SERVO
MOTOR AMPLIFIER
DIMMER SW
[COMB. SW]
CRUISE CONTROL
MIRROR SW
REAR WINDOW
DEFOGGER SW
POWER WINDOW
MASTER SW
POWER WINDOW
CONTROL RELAY
DOOR LOCK CONTROL
SW
REMOTE CONTROL
MIRROR SW
*The system shown here is an EXAMPLE ONLY. It is different to the actual circuit shown in the SYSTEM CIRCUITS SECTION.

To Ignition SW
IG Terminal
Fuse
Voltmeter SW 1
Relay
SW 2Solenoid[A]
[B]
[C]
Ohmmeter
SW
Ohmmeter
Diode
Digital Type Analog Type
2001 PRIUS (EWD414U)
C TROUBLESHOOTING
VOLTAGE CHECK
(a)Establish conditions in which voltage is present at the check
point.
Example:
[A] ± Ignition SW on
[B] ± Ignition SW and SW 1 on
[C] ± Ignition SW, SW 1 and Relay on (SW 2 off)
(b)Using a voltmeter, connect the negative lead to a good ground
point or negative battery terminal, and the positive lead to the
connector or component terminal.
This check can be done with a test light instead of a voltmeter.
CONTINUITY AND RESISTANCE CHECK
(a)Disconnect the battery terminal or wire so there is no voltage
between the check points.
(b)Contact the two leads of an ohmmeter to each of the check
points.
If the circuit has diodes, reverse the two leads and check
again.
When contacting the negative lead to the diode positive side
and the positive lead to the negative side, there should be
continuity.
When contacting the two leads in reverse, there should be no
continuity.
(c)Use a volt/ohmmeter with high impedance (10 kW/V
minimum) for troubleshooting of the electrical circuit.

10
3
0.2
11
(mm) Reference:
Tool Up Example:
(Case 1)
Terminal Retainer
Terminal Retainer
[Retainer at Full Lock Position]
[Retainer at Temporary Lock Position]StopperTerminal
Retainer
Secondary
Locking Device Example:
(Case 2)
2001 PRIUS (EWD414U)
C TROUBLESHOOTING
HOW TO REPLACE TERMINAL
(with terminal retainer or secondary locking device)
1.PREPARE THE SPECIAL TOOL
HINT : To remove the terminal from the connector, please
construct and use the special tool or like object shown on
the left.
2.DISCONNECT CONNECTOR
3.DISENGAGE THE SECONDARY LOCKING DEVICE OR
TERMINAL RETAINER.
(a)Locking device must be disengaged before the terminal
locking clip can be released and the terminal removed from
the connector.
(b)Use a special tool or the terminal pick to unlock the secondary
locking device or terminal retainer.
NOTICE:
Do not remove the terminal retainer from connector body.
[A] For Non±Waterproof Type Connector
HINT : The needle insertion position varies according to the
connector's shape (number of terminals etc.), so
check the position before inserting it.
ºCase 1º
Raise the terminal retainer up to the temporary lock
position.
ºCase 2º
Open the secondary locking device.

Retainer at
Full Lock Position
[Male] [Female] Retainer at
Temporary Lock Position
Locking Lug
Tool
2001 PRIUS (EWD414U)
C TROUBLESHOOTING
Push the terminal retainer down to the temporary lock position.
(c)Release the locking lug from terminal and pull the terminal out
from rear.
4.INSTALL TERMINAL TO CONNECTOR
(a)Insert the terminal.
HINT:
1. Make sure the terminal is positioned correctly.
2. Insert the terminal until the locking lug locks firmly.
3. Insert the terminal with terminal retainer in the temporary lock
position.
(b)Push the secondary locking device or terminal retainer in to
the full lock position.
5.CONNECT CONNECTOR

2001 PRIUS (EWD414U)
SRS
NOTICE: When inspecting or repairing the SRS, perform the operation in accordance with the following precautionary
instructions and the procedure and precautions in the Repair Manual for the applicable model year.

Malfunction symptoms of the SRS are difficult to confirm, so the DTCs become the most important source of information
when troubleshooting. When troubleshooting the SRS, always inspect the DTCs before disconnecting the battery.

Work must be started after 90 seconds from when the ignition switch is turned to the ºLOCKº position and the
negative (±) terminal cable is disconnected from the battery.
(The SRS is equipped with a back±up power source so that if work is started within 90 seconds from
disconnecting the negative (±) terminal cable of the battery, the SRS may be deployed.)

When the negative (±) terminal cable is disconnected from the battery, the memory of the clock and audio system will be
canceled. So before starting work, make a record of the contents memorized in the audio memory system. When work is
finished, reset the audio systems as they were before and adjust the clock. To avoid erasing the memory in each
memory system, never use a back±up power supply from outside the vehicle.

Before repairs, remove the airbag sensor if shocks are likely to be applied to the sensor during repairs.

Do not expose the steering wheel pad, front passenger airbag assembly, side airbag assembly, seat belt pretensioner,
airbag sensor assembly or side airbag sensor directly to hot air or flames.

Even in cases of a minor collision where the SRS does not deploy, the steering wheel pad, front passenger airbag
assembly, side airbag assembly, seat belt pretensioner, airbag sensor assembly and side airbag sensor assembly
should be inspected.

Never use SRS parts from another vehicle. When replacing parts, replace them with new parts.

Never disassemble and repair the steering wheel pad, front passenger airbag assembly, side airbag assembly, seat belt
pretensioner, airbag sensor assembly or side airbag sensor assembly in order to reuse it.

If the steering wheel pad, front passenger airbag assembly, side airbag assembly, seat belt pretensioner, airbag sensor
assembly or side airbag sensor assembly has been dropped, or if there are cracks, dents or other defects in the case,
bracket or connector, replace them with new ones.

Use a volt/ohmmeter with high impedance (10 kW/V minimum) for troubleshooting the system's electrical circuits.

Information labels are attached to the periphery of the SRS components. Follow the instructions on the notices.

After work on the SRS is completed, perform the SRS warning light check.

If the vehicle is equipped with a mobile communication system, refer to the precaution in the IN section of the Repair
Manual.

THS (TOYOTA HYBRID SYSTEM)
182TH22
1. READY Light
2. Output Control
Warning Light 3. Master Warning Light
4. Malfunction Indicator light 5. Discharge Warning Light
6. EMPS Malfunction
Warning Light7. HV Battery Warning Light
8. Hybrid System
Malfunction Warning
Light 32
INDICATOR AND WARNING LIGHT
The warning lights of the Prius are different from those on conventional vehicles. Inspection and repair
should be performed while referring to the troubleshooting section in the 2001 Prius repair manual
(RM778U).

Center Meter 
Multi Information Display 
1. READY lightTurns on when the ignition switch is turned to START to indicate that the ve-
hicle is ready to drive.
2. Output control
warning lightTurns on when the remaining HV battery charge becomes insufficient at R
range or when there is an abnormal temperature rise in the HV battery due
to continuous driving under heavy loads. It may also light when the HV bat-
tery temperature is low (after starting at low temperatures). The hybrid sys-
tem output is limited while this light is on.
Travel at reduced speeds (avoid sudden acceleration) while the light is lit.
3. Master warning
lightTurns on with buzzer sounding by linked operation with warning lights ª6º
to ª8º on the multi center display.
4. Malfunction
indicator lightTurns on when there is a malfunction in the engine control system.
5. Discharge warning
lightTurns on when there is a malfunction in the 12 V charging system (converter
assembly).
If it turns on together with the master warning light and hybrid system
warning light, check the diagnostic code.
6. EMPS malfunction
warning lightTurns on when there is a malfunction in the EMPS control system.
7. HV battery warning
lightTurns on when the HV battery is discharged to the lower limit.
8. Hybrid system
warning lightTurns on when a malfunction in MG1, 2, inverter, HV battery or HV ECU
is detected.

IN00U±36
N17080
Filler Cap
Float
Reservoir
 Grommet
Clip
Slotted Spring Pin
: Specified torque
 Non±reusable partCylinder
Piston
Push Rod
Washer
Snap Ring
Boot
 Gasket
Lock Nut
Clevis Pin
Clevis
N´m (kgf´cm, ft´lbf)
12 (120, 9)
15 (155, 11)
± INTRODUCTIONHOW TO USE THIS MANUAL
IN±1
1 Author: Date:
2001 PRIUS (RM778U)
HOW TO USE THIS MANUAL
GENERAL INFORMATION
1. INDEX
An INDEX is provided on the first page of each section to guide you to the item to be repaired. To assist you
in finding your way through the manual, the section title and major heading are given at the top of every page.
2. PRECAUTION
At the beginning of each section, a PRECAUTION is given that pertains to all repair operations contained
in that section.
Read these precautions before starting any repair task.
3. TROUBLESHOOTING
TROUBLESHOOTING tables are included for each system to help you diagnose the problem and find the
cause. The fundamentals of how to proceed with troubleshooting are described on page IN±30.
Be sure to read this before performing troubleshooting.
4. PREPARATION
Preparation lists the SST (Special Service Tools), recommended tools, equipment, lubricant and SSM (Spe-
cial Service Materials) which should be prepared before beginning the operation and explains the purpose
of each one.
5. REPAIR PROCEDURES
Most repair operations begin with an overview illustration. It identifies the components and shows how the
parts fit together.
Example: