O2 sensor TOYOTA PRIUS 2001 Service Repair Manual

FI7187
IN0379
Sensor Side
ECU Side
IN0378
Sensor SideECU Side
IN0380
Sensor SideECU Side
IN0381
Pull Lightly
Looseness of Crimping
IN±42± INTRODUCTIONHOW TO TROUBLESHOOT ECU CONTROLLED
SYSTEMS
2001 PRIUS (RM778U)
2. CONNECTOR HANDLING
When inserting tester probes into a connector, insert them from
the rear of the connector. When necessary, use mini test leads.
For water resistant connectors which cannot be accessed from
behind, take good care not to deform the connector terminals.
3. CONTINUITY CHECK (OPEN CIRCUIT CHECK)
(a) Disconnect the connectors at both ECU and sensor
sides.
(b) Measure the resistance between the applicable terminals
of the connectors.
Resistance: 1 W or less
HINT:
Measure the resistance while lightly shaking the wire harness
vertically and horizontally.
4. RESISTANCE CHECK (SHORT CIRCUIT CHECK)
(a) Disconnect the connectors on both ends.
(b) Measure the resistance between the applicable terminals
of the connectors and body ground. Be sure to carry out
this check on the connectors on both ends.
Resistance: 1 MW or higher
HINT:
Measure the resistance while lightly shaking the wire harness
vertically and horizontally.
5. VISUAL CHECK AND CONTACT PRESSURE CHECK
(a) Disconnect the connectors at both ends.
(b) Check for rust or foreign material, etc. in the terminals of
the connectors.
(c) Check crimped portions for looseness or damage and
check that the terminals are secured in lock portion.
HINT:
The terminals should not come out when pulled lightly from the
back.

Z17004
Fig. 1
OPENECU
2 Sensor
22 21 111A B C
Z17005
Fig. 2
ECU
Sensor
21A
B C
1
1
22
B04722
Fig. 3
ECU
Sensor
21A B1 C
1
1
221
2 B2
± INTRODUCTIONHOW TO TROUBLESHOOT ECU CONTROLLED
SYSTEMSIN±43
2001 PRIUS (RM778U)
(d) Prepare a test male terminal and insert it in the female ter-
minal, then pull it out.
NOTICE:
When testing a gold±plated female terminal, always use a
gold±plated male terminal.
HINT:
When the test terminal is pulled out more easily than others,
there may be poor contact in that section.
6. CHECK OPEN CIRCUIT
For the open circuit in the wire harness in Fig. 1, perform º(a)
Continuity Checkº or º(b) Voltage Checkº to locate the section.
(a) Check the continuity.
(1) Disconnect connectors ºAº and ºCº and measure
the resistance between them.
In the case of Fig. 2:
Between terminal 1 of connector ºAº and terminal 1
of connector ºCº " No continuity (open)
Between terminal 2 of connector ºAº and terminal 2
of connector ºCº " Continuity
Therefore, it is found out that there is an open circuit
between terminal 1 of connector ºAº and terminal 1
of connector ºCº.
(2) Disconnect connector ºBº and measure the resis-
tance between the connectors.
In the case of Fig. 3:
Between terminal 1 of connector ºAº and terminal 1
of connector ºB1º " Continuity
Between terminal 1 of connector ºB2º and terminal
1 of connector ºCº " No continuity (open)
Therefore, it is found out that there is an open circuit
between terminal 1 of connector ºB2º and terminal
1 of connector ºCº.

Z17007
Fig. 4
Sensor
21A
C
1
1
22B5V
5V
5V
0V
Z17008
Fig. 5
2 1A C
1
1
22
BSHORT
Z17009
Fig. 6
21A C
1
1
22
BSensorECU IN±44
± INTRODUCTIONHOW TO TROUBLESHOOT ECU CONTROLLED
SYSTEMS
2001 PRIUS (RM778U)
(b) Check the voltage.
In a circuit in which voltage is applied (to the ECU connec-
tor terminal), an open circuit can be checked for by con-
ducting a voltage check.
As shown in Fig. 4, with each connector still con-
nected, measure the voltage between body ground
and terminal 1 of connector ºAº at the ECU 5V out-
put terminal, terminal 1 of connector ºBº, and termi-
nal 1 of connector ºCº, in that order.
If the results are:
5V: Between Terminal 1 of connector ºAº and Body Ground
5V: Between Terminal 1 of connector ºBº and Body Ground
0V: Between Terminal 1 of connector ºCº and Body Ground
Then it is found out that there is an open circuit in the wire har-
ness between terminal 1 of ºBº and terminal 1 of ºCº.
7. CHECK SHORT CIRCUIT
If the wire harness is ground shorted as in Fig. 5, locate the sec-
tion by conducting a ºcontinuity check with groundº.
Check the continuity with ground.
(1) Disconnect connectors ºAº and ºCº and measure
the resistance between terminal 1 and 2 of connec-
tor ºAº and body ground.
In the case of Fig. 6:
Between terminal 1 of connector ºAº and body
ground " Continuity (short)
Between terminal 2 of connector ºAº and body
ground " No continuity
Therefore, it is found out that there is a short circuit
between terminal 1 of connector ºAº and terminal 1
of connector ºCº.

Z17808
Fig. 7
Sensor
21A B1 C
1
1
221
2 B2
ECU
IN0383
Example
Ground
IN0384
Ground
Ground
ECU Side
W/H Side
± INTRODUCTIONHOW TO TROUBLESHOOT ECU CONTROLLED
SYSTEMSIN±45
2001 PRIUS (RM778U)
(2) Disconnect connector ºBº and measure the resis-
tance between terminal 1 of connector ºAº and body
ground, and terminal 1 of connector ºB2º and body
ground.
In the case of Fig. 7:
Between terminal 1 of connector ºAº and body
ground " No continuity
Between terminal 1 of connector ºB2º and body
ground " Continuity (short)
Therefore, it is found out that there is a short circuit
between terminal 1 of connector ºB2º and terminal
1 of connector ºCº.
8. CHECK AND REPLACE ECU
First check the ECU ground circuit. If it is faulty, repair it. If it is
normal, the ECU could be faulty, so replace the ECU with a nor-
mal functioning one and check that the symptoms appear.
(1) Measure the resistance between the ECU ground
terminal and the body ground.
Resistance: 1 W or less
(2) Disconnect the ECU connector, check the ground
terminals on the ECU side and the wire harness
side for bend and check the contact pressure.

IN04Q±11
IN±46
± INTRODUCTIONTERMS
46 Author: Date:
2001 PRIUS (RM778U)
TERMS
ABBREVIATIONS USED IN THIS MANUAL
AbbreviationsMeaning
ABSAnti±Lock Brake System
ACAlternating Current
ACCAccessory
ACISAcoustic Control Induction System
ACSDAutomatic Cold Start Device
A.D.D.Automatic Disconnecting Differential
A/FAir±Fuel Ratio
AHCActive Height Control Suspension
ALRAutomatic Locking Retractor
ALTAlternator
AMPAmplifier
ANTAntenna
APPROX.Approximately
A/TAutomatic Transmission (Transaxle)
AT FAutomatic Transmission Fluid
AUTOAutomatic
AUXAuxiliary
AV GAverage
AV SAdaptive Variable Suspension
BABrake Assist
BACSBoost Altitude Compensation System
BATBattery
BDCBottom Dead Center
B/LBi±Level
B/SBore±Stroke Ratio
BTDCBefore Top Dead Center
BVSVBimetallic Vacuum Switching Valve
Calif.California
CBCircuit Breaker
CCoCatalytic Converter For Oxidation
CDCompact Disc
CFCornering Force
CGCenter Of Gravity
CHChannel
COMB.Combination
CPECoupe
CPSCombustion Pressure Sensor
CPUCentral Processing Unit
CRSChild Restraint System
CTRCenter
C/VCheck Valve
CVControl Valve

± INTRODUCTIONTERMS
IN±49
49 Author: Date:
2001 PRIUS (RM778U) N
Neutral
NANatural Aspiration
No.Number
O/DOverdrive
OEMOriginal Equipment Manufacturing
OHCOverhead Camshaft
OHVOverhead Valve
OPTOption
O/SOversize
P & BVProportioning And Bypass Valve
PCSPower Control System
PCVPositive Crankcase Ventilation
PKBParking Brake
PPSProgressive Power Steering
PSPower Steering
PTOPower Take±Off
R & PRack And Pinion
R/BRelay Block
RBSRecirculating Ball Type Steering
R/FReinforcement
RFSRigid Front Suspension
RHRight±Hand
RHDRight±Hand Drive
RLYRelay
ROMRead Only Memory
RrRear
RRRear±Engine Rear±Wheel Drive
RRSRigid Rear Suspension
RWDRear±Wheel Drive
SDNSedan
SENSensor
SICSStarting Injection Control System
SOCState Of Charge
SOHCSingle Overhead Camshaft
SPECSpecification
SPISingle Point Injection
SRSSupplemental Restraint System
SSMSpecial Service Materials
SSTSpecial Service Tools
STDStandard
STJCold±Start Fuel Injection
SWSwitch
SYSSystem
T/ATransaxle
TACHTachometer
TBIThrottle Body Electronic Fuel Injection

IN±52
± INTRODUCTIONTERMS
2001 PRIUS (RM778U) HO2S
Heated Oxygen SensorHeated Oxygen Sensor (HO2S)
IACIdle Air ControlIdle Speed Control (ISC)
IATIntake Air TemperatureIntake or Inlet Air Temperature
ICMIgnition Control Module±
IFIIndirect Fuel InjectionIndirect Injection (IDL)
IFSInertia Fuel±Shutoff±
ISCIdle Speed Control±
KSKnock SensorKnock Sensor
MAFMass Air FlowAir Flow Meter
MAPManifold Absolute PressureManifold Pressure
Intake Vacuum
MCMixture Control
Electric Bleed Air Control Valve (EBCV)
Mixture Control Valve (MCV)
Electric Air Control Valve (EACV)
MDPManifold Differential Pressure±
MFIMultiport Fuel InjectionElectronic Fuel Injection (EFI)
MILMalfunction Indicator LampCheck Engine Lamp
MSTManifold Surface Temperature±
MVZManifold Vacuum Zone±
NVRAMNon±Volatile Random Access Memory±
O2SOxygen SensorOxygen Sensor, O2 Sensor (O2S)
OBDOn±Board DiagnosticOn±Board Diagnostic System (OBD)
OCOxidation Catalytic ConverterOxidation Catalyst Convert (OC), CCo
OPOpen LoopOpen Loop
PAIRPulsed Secondary Air InjectionAir Suction (AS)
PCMPowertrain Control Module±
PNPPark/Neutral Position±
PROMProgrammable Read Only Memory±
PSPPower Steering Pressure±
PTOXPeriodic Trap OxidizerDiesel Particulate Filter (DPF)
Diesel Particulate Trap (DPT)
RAMRandom Access MemoryRandom Access Memory (RAM)
RMRelay Module±
ROMRead Only MemoryRead Only Memory (ROM)
RPMEngine SpeedEngine Speed
SCSuperchargerSupercharger
SCBSupercharger BypassE±ABV
SFISequential Multiport Fuel InjectionElectronic Fuel Injection (EFI), Sequential Injection
SPLSmoke Puff Limiter±
SRIService Reminder Indicator±
SRTSystem Readiness Test±
STScan Tool±
TBThrottle BodyThrottle Body
TBIThrottle Body Fuel InjectionSingle Point Injection
Central Fuel Injection (Ci)
TCTurbochargerTurbocharger
TCCTorque Converter ClutchTorque Converter

± INTRODUCTIONTERMS
IN±53
2001 PRIUS (RM778U) TCM
Transmission Control ModuleTransmission ECU, ECT ECU
TPThrottle PositionThrottle Position
TRTransmission Range±
TVVThermal Vacuum ValveBimetallic Vacuum Switching Valve (BVSV)
Thermostatic Vacuum Switching Valve (TVSV)
TWCThree±Way Catalytic Converter
Three±Way Catalytic (TWC)
Manifold Converter
CC
RO
TWC+OCThree±Way + Oxidation Catalytic ConverterCCR + CCo
VA FVolume Air FlowAir Flow Meter
VRVoltage RegulatorVoltage Regulator
VSSVehicle Speed SensorVehicle Speed Sensor
WOTWide Open ThrottleFull Throttle
WU±OCWarm Up Oxidation Catalytic Converter±
WU±TWCWarm Up Three±Way Catalytic Converter±
3GRThird Gear±
4GRFourth Gear±

PP3AF±02
PP±60
± PREPARATIONAIR CONDITIONING
2001 PRIUS (RM778U)
EQUIPMENT
Voltmeter
Ammeter
Ohmmeter
Test lead
ThermometerSensor, ECT switch
Torque wrench
Dial indicatorMagnetic clutch
Plastic hammerMagnetic clutch

SS175±03
SS±10
± SERVICE SPECIFICATIONSENGINE MECHANICAL
2001 PRIUS (RM778U)
TORQUE SPECIFICATION
Part tightenedN´mkgf´cmft´lbf
Plug x Timing chain cover1515011
Chain vibration damper x Cylinder block9.09280 in .´lbf
Chain tensioner9.09280 in .´lbf
Timing chain cover Bolt A
Bolt B
Bolt C
Bolt D
Bolt E
Nut F
Nut G11
24
11
24
11
24
1111 2
245
11 2
245
11 2
245
11 28
18
8
18
8
18
8
RH engine mounting bracket x Timing chain cover5556141
Crankshaft position sensor x Timing chain cover Bolt A
Bolt B7.5
1176
11 266 in .´lbf
8
Oil control valve8.08271 in .´lbf
Crankshaft pulley x Crankshaft1281,30094
Cylinder head cover x Cylinder101007
RH engine mounting insulator Bolt A
Bolt B
Nut45
52
52459
530
53033
38
38
Cylinder head x Cylinder block 1st
2nd
3rd29.4
Turn 90°
Turn 90°300
Turn 90°
Turn 90°22
Turn 90°
Turn 90°
Water bypass pipe x Cylinder head9.09280 in .´lbf
No. 1 camshaft bearing cap x Cylinder head2323517
No. 2 camshaft bearing cap x Cylinder head12.713010
Camshaft timing sprocket x Camshaft6465047
Valve timing controller assembly x Camshaft6465047
Intake manifold x Cylinder head2020415
Exhaust manifold x Cylinder head2727520
Upper heat insulator x Exhaust manifold8.08271 in .´lbf
Exhaust manifold stay x Cylinder block2727520
Front exhaust pipe x Tailpipe Bolt A
Bolt B62
32630
33046
24
Connecting rod cap x Connecting rod 1st
2nd15
Turn 90°150
Turn 90°11
Turn 90°
Bearing cap x Cylinder block 1st
2nd22
Turn 90°220
Turn 90°16
Turn 90°
Oil pan No. 1 x Cylinder block2424518
Oil strainer x Oil pan No. 11111 28
Oil pan No. 2 x Oil pan No. 19.09280 in.´lbf
Oil filter union x Oil pan No. 13030621
Engine coolant drain plug x Cylinder block12.71309
Knock sensor x Cylinder block4445033
Water bypass pipe x Cylinder block9.09080 in.´lbf
Flywheel x Crankshaft8485762
Damper spring x Flywheel1616312