2001 TOYOTA PRIUS relay

B04758
IN±20
± INTRODUCTIONFOR ALL OF VEHICLES
20 Author: Date:
2001 PRIUS (RM778U)
(6) If a damage to any of the high±voltage components
and cables is suspected, cut the high±voltage cir-
cuit using the procedure below:

Move the shift lever to the P position and en-
gage the parking brake.

Remove the ignition key. Then disconnect the
cable from the negative (±) terminal of the
auxiliary battery.

Wear insulated gloves, and then remove the
service plug.

If you cannot remove the service plug due to
damage to the rear portion of the vehicle, re-
move the HV fuse or IGCT relay instead.
(g) Precautions to be taken when disposing of the vehicle
When scrapping the vehicle, remove the HV battery from
the vehicle and return it through the route specified by the
manufacturer. The same applies to any damaged HV bat-
tery.
(h) Precautions to be observed when towing
Tow the damaged vehicle with its front wheels or its front
and rear wheels lifted off the ground.
NOTICE:
Towing the damaged vehicle with its front wheels on the
ground may cause the motor to generate electricity. This
electricity could, depending on the nature of the damage,
leak and cause a fire.
(i) Towing with 4 wheels on the ground
NOTICE:

If you have to tow the damaged vehicle using a rope,
do it at a speed below 30 km/h. Such towing operation
is allowed only to cover very short distance, such as
the distance to a tow truck lorry, for example.

Set the ignition switch to the ACC position and shift
lever to the N position.

If you detect any abnormality in the damaged vehicle
during the towing operation, stop the towing opera-
tion immediately.
(j) Towing eyelet
(1) Install the hook.
(2) Hook a rope onto the illustrated point for towing.

V07268
VIBRATION METHOD: When vibration seems to be the major cause.
CONNECTORS
WIRE HARNESS
PARTS AND SENSOR1
Slightly shake the connector vertically and horizontally.
Slightly shake the wire harness vertically and horizontally.
The connector joint, fulcrum of the vibration, and body
through portion are the major areas to be checked thorough-
ly.
Apply slight vibration with a finger to the part of the sensor
considered to be the problem cause and check that the mal-
function occurs.Shake Slightly
Swing Slightly
Vibrate Slightly
HINT:
Applying strong vibration to relays may result in open relays.
± INTRODUCTIONHOW TO TROUBLESHOOT ECU CONTROLLED
SYSTEMSIN±35
2001 PRIUS (RM778U)
3. SYMPTOM SIMULATION
The most difficult case in troubleshooting is when there are no problem symptoms occurring. In such cases,
a thorough customer problem analysis must be carried out, then simulate the same or similar conditions and
environment in which the problem occurred in the customer's vehicle. No matter how much experience a
technician has, or how skilled he may be, if he proceeds to troubleshoot without confirming the problem
symptoms he will tend to overlook something important in the repair operation and make a wrong guess
somewhere, which will only lead to a standstill. For example, for a problem which only occurs when the en-
gine is cold, or for a problem which occurs due to vibration caused by the road during driving, etc., the prob-
lem can never be determined so long as the symptoms are confirmed with the engine hot condition or the
vehicle at a standstill. Since vibration, heat or water penetration (moisture) is likely cause for problem which
is difficult to reproduce, the symptom simulation tests introduced here are effective measures in that the ex-
ternal causes are applied to the vehicle in a stopped condition.
Important Points in the Symptom Simulation Test:
In the symptom simulation test, the problem symptoms should of course be confirmed, but the problem area
or parts must also be found out. To do this, narrow down the possible problem circuits according to the symp-
toms before starting this test and connect a tester beforehand. After that, carry out the symptom simulation
test, judging whether the circuit being tested is defective or normal and also confirming the problem symp-
toms at the same time. Refer to the problem symptoms table for each system to narrow down the possible
causes of the symptom.

IN±38± INTRODUCTIONHOW TO TROUBLESHOOT ECU CONTROLLED
SYSTEMS
2001 PRIUS (RM778U)
5. PROBLEM SYMPTOMS TABLE
The suspected circuits or parts for each problem symptom are shown in the table below. Use this table to
troubleshoot the problem when a ºNormalº code is displayed in the diagnostic trouble code check but the
problem is still occurring. Numbers in the table indicate the inspection order in which the circuits or parts
should be checked.
HINT:
When the problem is not detected by the diagnostic system even though the problem symptom is present,
it is considered that the problem is occurring outside the detection range of the diagnostic system, or that
the problem is occurring in a system other than the diagnostic system.
Symptom
Suspect AreaSee page
Engine does not crank (Does not start)
No initial combustion (Does not start)
No complete combustion (Does not start)1. Starter and starter relay
1. ECM power source circuit
2. Fuel pump control circuit
3. Engine control module (ECM)
1. Starter signal circuit
2. Fuel pump control circuit1. Fuel pump control circuitDI±147
DI±151
IN±29
PROBLEM SYMPTOMS TABLE
1. Compression
2. Fuel pump control circuit 1. A/C signal circuit
2. Fuel pump control circuit 1. A/C signal circuit (Compressor circuit)
2. ECM power source circuit 1. Starter signal circuit
2. Fuel pump control circuit1. Starter signal circuit
2. Fuel pump control circuit
3. Compression
idling) High engine idle speed (Poor idling) Hot engine Cold engine (Difficult to start)Engine cranks normally (Difficult to start)
AC±88 DI±144
DI±151
EM±3 DI±151

Problem Symptom
Page
Indicates the page where the flow chart for each circuit
is located.

Circuit Inspection, Inspection Order
Indicates the circuit which needs to be checked for each problem
symptom. Check in the order indicated by the numbers.

Circuit or Part Name
Indicates the circuit or part which needs to be checked.
ST±2
ST±17
DI±144
DI±151
DI±144
DI±151

± 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

SS02V±05
± SERVICE SPECIFICATIONSBODY ELECTRICAL
SS±33
155 Author: Date:
2001 PRIUS (RM778U)
BODY ELECTRICAL
SERVICE DATA
DAYTIME RUNNING RELAY (MAIN) (Wire harness side)
12 ± Ground (Ignition switch OFF)No voltage
12 ± Ground (Ignition switch ON)Battery voltage
9 ± Ground (Engine Running)Battery voltage
3 ± Ground (Constant)Battery voltage
6 ± Ground (Constant)Battery voltage
SPEEDOMETER (ON±VEHICLE)
Standard indication (mph)Allowable range (mph)
2018 ± 22
4038 ± 42
6059 ± 63
8079 ± 83
10099 ± 104
120119 ± 125
Standard indication (km/h)Allowable range (km/h)
2018 ± 22
4038 ± 42
6058 ± 62
8078 ± 82
10097 ± 103
120117 ± 123
140137 ± 143
160157 ± 163
FUEL SENDER GAUGE
Float position mm (in.)Resistance (W)
F: Approx. 25.2 (0.99)Approx. 430
1/2: Approx. 92.6 (3.65)Approx. 1000 ± 2000
E: Approx. 169 (6.65)Approx. 5000
DEFOGER SWITCH (Wire harness side)
1 ± Ground (Ignition switch LOCK or ACC)No voltage
1 ± Ground (Ignition switch ON)Battery voltage
8 ± Ground (Constant)Battery voltage
WIRELESSS DOOR LOCK CONTROL RECEIVER (Wire harness side)
5 ± Ground (Constant)Battery voltage
POWER MIRROR SWITCH (Wire harness side)
8 ± Ground (Ignition switch LOCK)No voltage
8 ± Ground (Ignition switch ACC or ON)Battery voltage
RADIO RECEIVER (Wire harness side)
3 ± Ground (Ignition switch LOCK)No voltage
3 ± Ground (Ignition switch ACC or ON)Battery voltage
4 ± Ground (Constant)Battery voltage
CENTER CLUSTER SWITCH (Wire harness side)
1 ± Ground (Ignition switch ACC or ON)Battery voltage

A14050
G±R
(Shielded)
512
IA2
1A
3
2
1
1EFI
3
B±G
F13B
MAIN
FL Block No. 1
BatteryEngine Room J/B
BR 1F
1K 1
2 3
11BW±B4
EB A
J7
J/C 1 2M1 Mass
Air Flow
Meter
A A 3
BE9
E810
VG
EVGECM
EFI
Relay
IEMREL
E8 G±R
19 G
R
F18 FL Block No. 2
F12W±B
J1
J/CJ9
J/C A
AW±B25
DI±24
± DIAGNOSTICSENGINE
2001 PRIUS (RM778U)
WIRING DIAGRAM
INSPECTION PROCEDURE
HINT:
Read freeze frame data using TOYOTA hand±held tester or OBD II scan tool. Because freeze frame records
the engine conditions when the malfunction is detected, when troubleshooting it is useful for determining
whether the vehicle was running or stopped, the engine warmed up or not, the air±fuel ratio lean or rich, etc.
at the time of the malfunction.
1 Connect OBD II scan tool or TOYOTA hand±held tester, and read value of mass
air flow rate.
PREPARATION:
(a) Connect the OBD II scan tool or TOYOTA hand±held tester to the DLC3.
(b) Turn ignition switch ON and push the OBD II scan tool or TOYOTA hand±held tester main switch ON.
(c) Start the engine.
CHECK:
Read mass air flow rate on the OBD II scan tool or TOYOTA hand±held tester.
RESULT:
Type IType II
Mass air flow rate (gm/sec.)0.0271.0 or more

BE6653A01589
A01588
ON
3 (+)
A13618
VG (+)
START
± DIAGNOSTICSENGINE
DI±25
2001 PRIUS (RM778U)
Type I Go to step 2.
Type II Go to step 5.
2 Check voltage of mass air flow meter power source.
PREPARATION:
(a) Disconnect the mass air flow meter connector.
(b) Turn ignition switch ON.
CHECK:
Measure voltage between terminal 4 of mass air flow meter con-
nector and body ground.
OK:
Voltage: 9 ± 14 V
NG Check for open in harness and connector
between EFI main relay (Marking: EFI) and
mass air flow meter (See page IN±41).
OK
3 Check voltage between terminal VG of ECM connector and body ground.
PREPARATION:
(a) Remove the ECM with connector still connected (See
page SF±62).
(b) Start the engine.
CHECK:
Measure voltage between terminal VG of ECM and body
ground while engine is idling.
OK:
Voltage:
1.1 ± 1.5 V (P position and A/C switch OFF)
OK Check and replace ECM (See page IN±41).
NG