TOYOTA PRIUS 2001 Service Repair Manual

± DIAGNOSTICSENGINE
DI±13
2001 PRIUS (RM778U)O2 LR B1, S1 *
Heated Oxygen Sensor Lean Rich Bank 1, Sen-
sor 1 Response time for oxygen sensor output to
switch from lean to rich
Idling after warmed up: 0 ± 1,000 msec.
O2 RL B1, S1 *
Heated Oxygen Sensor Rich Lean Bank 1, Sen-
sor 1 Response time for oxygen sensor output to
switch from rich to lean
Idling after warmed up: 0 ± 1,000 msec.
*: If no conditions are specifically stated for ºldlingº, it means the shift lever is at P position, the A/C switch
is OFF and all accessory switches are OFF.

DI6UT±02
DI±14
± DIAGNOSTICSENGINE
2001 PRIUS (RM778U)
DIAGNOSTIC TROUBLE CODE CHART
HINT:
Parameters listed in the chart may not be exactly the same as your reading due to the type of instru-
ment or other factors.
If a malfunction code is displayed during the DTC check in check mode, check the circuit for that code
listed in the table below. For details of each code, turn to the page referred to under the ''See page
'' for the respective ''DTC No.'' in the DTC chart.
When the ignition switch is ON and ºREADYº indicator light is OFF, the bulb check of the ºMILº is per-
formed (ºMILº is ON).
When ºMILº is ON, but the DTC of the engine is not memorized, it may be because of HV control system
abnormality, so check HV control system beforehand.
SAE CONTROLLED:
DTC No.Detection ItemTrouble AreaMIL*1Memory
P0100
(DI±23)Mass Air Flow Circuit Malfunc-
tionOpen or short in mass air flow meter circuit
Mass air flow meter
ECM

P0101
(DI±27)Mass Air Flow Circuit Range/
Performance ProblemMass air flow meter
P0110
(DI±28)Intake Air Temp. Circuit Malfunc-
tionOpen or short in intake air temp. sensor circuit
Intake air temp. sensor (built into mass air flow meter)
ECM

P0115
(DI±32)Engine Coolant Temp. Circuit
MalfunctionOpen or short in engine coolant temp. sensor circuit
Engine coolant temp. sensor
ECM

P0116
(DI±36)Engine Coolant Temp. Circuit
Range/Performance ProblemCooling system
Engine coolant temp. sensor
P0120
(DI±38)Throttle/Pedal Position Sensor/
Switch ºAº Circuit MalfunctionOpen or short in throttle position sensor circuit
Throttle position sensor
ECM

P0121
(DI±43)Throttle/Pedal Position Sensor/
Switch ºAº Circuit Range/Perfor-
mance ProblemThrottle position sensor
ECM
P0125
(DI±44)Insufficient Coolant Temp. for
Closed Loop Fuel Control
Open or short in heated oxygen sensor (bank 1 sensor 1)
circuit
Heated oxygen sensor (bank 1 sensor 1)
Air induction system
Fuel pressure
Injector
Gas leakage on exhaust system
ECM

P0128
(DI±49)Thermostat Malfunction
Thermostat
Cooling system
Water temperature
ECM

P0130
(DI±50)Heated Oxygen Sensor Circuit
Malfunction (Bank 1 Sensor 1)
(Except Calif.)
Open or short in heated oxygen sensor circuit
Heated oxygen sensor
Air induction system
EGR system
Fuel pressure
Injector
ECM


± DIAGNOSTICSENGINE
DI±15
2001 PRIUS (RM778U)P0133
(DI±54)
Oxygen Sensor Circuit Slow Re-
sponse (Bank 1 Sensor 1)
Open or short in heated oxygen sensor circuit
Heated oxygen sensor
Air induction system
EGR system
Fuel pressure
Injector
ECM

P0135
(DI±57)Oxygen Sensor Heater Circuit
Malfunction (Bank 1 Sensor 1)Open or short in heater circuit of heated oxygen sensor
Heated oxygen sensor heater
ECM

P0136
(DI±59)Oxygen Sensor Circuit Malfunc-
tion (Bank 1 Sensor 2)Open or short in heated oxygen sensor circuit
Heated oxygen sensor
P0141
(DI±57)Oxygen Sensor Heater Circuit
Malfunction (Bank 1 Sensor 2)Same as DTC No. P0135
P0171
(DI±61)System too Lean (Fuel Trim)
Air induction system
Injector blockage
Mass air flow meter
Engine coolant temp. sensor
Fuel pressure
Gas leakage on exhaust system
Open or short in heated oxygen sensor (bank 1 sensor 1)
circuit
Heated oxygen sensor (bank 1 sensor 1)

P0172
(DI±61)System too Rich (Fuel Trim)
Injector leak, blockage
Mass air flow meter
Engine coolant temp. sensor
Ignition system
Fuel pressure
Gas leakage on exhaust system
Open or short in heated oxygen sensor (bank 1, 2 sensor 1)
circuit
Heated oxygen sensor (bank 1, 2 sensor 1)
ECM

P0300
(DI±65)Random/Multiple Cylinder Misfire
DetectedOpen or short in engine wire
Connector connection
Vac m hose connectionP0301
(DI±65)Cylinder 1 Misfire Detected
Vacuum hose connection
Ignition system
Injector
P0302
(DI±65)Cylinder 2 Misfire Detected
j
Fuel pressure
EGR system

Manifold absolutepressure sensor

P0303
(DI±65)Cylinder 3 Misfire Detected
Manifold absolute pressure sensor
Engine coolant temp. sensor
Compression pressure
Vl lP0304
(DI±65)Cylinder 4 Misfire Detected
Valve clearance
Valve timing
ECM
P0325
(DI±71)Knock Sensor 1 Circuit Malfunc-
tion (Bank 1)Open or short in knock sensor 1 circuit
Knock sensor 1 (looseness)
ECM

P0335
(DI±74)Crankshaft Position Sensor ºAº
Circuit Malfunction
Open or short in crankshaft position sensor circuit
Crankshaft position sensor
Signal plate (Timing belt guide)
Crankshaft timing pulley
ECM


DI±16
± DIAGNOSTICSENGINE
2001 PRIUS (RM778U)P0340
(DI±76)
Camshaft Position Sensor Cir-
cuit Malfunction
Open or short in camshaft position sensor circuit
Camshaft position sensor
Camshaft timing pulley
ECM

P0420
(DI±78)Catalyst System Efficiency Be-
low Threshold (Bank 1)
Gas leakage on exhaust system
Open or short in heated oxygen sensor circuit
Heated oxygen sensor
Three±way catalytic converter

P0440
(DI±81)Evaporative Emission Control
System Malfunction
Hose or tube cracked, hole, damaged or loose seal
Fuel tank cap incorrectly installed
Fuel tank cap cracked or damaged
Vacuum hose cracked, hole, blocked,damaged or discon-
nected
Fuel tank cracked, hole or damaged
Charcoal canister cracked, hole or damaged
Open or short in vapor pressure sensor circuit
Vapor pressure sensor
Fuel tank over fill check valve cracked or damaged
ECM

P0441
(DI±87)Evaporative Emission Control
System Incorrect Purge Flow
Vacuum hose cracked, hole, blocked damaged or discon-
nected
Open or short in vapor pressure sensor circuit
Vapor pressure sensor
Open or short in VSV circuit for EVAP
VSV for EVAP
P0446
(DI±87)Evaporative Emission Control
System Vent Control Malfunction
VSV for EVAP
Open or short in VSV circuit for vapor pressure sensor
VSV for vapor pressure sensor
Charcoal canister cracked, hole or damaged
Fuel tank over fill check valve cracked or damaged
ECM
P0450
(DI±103)Evaporative Emission Control
System Pressure Sensor Mal-
function
Open or short in vapor pressure sensor circuit
V
P0451
(DI±103)Evaporative Emission Control
System Pressure Sensor Range/
PerformanceVapor pressure sensor
ECM
P0500
(DI±105)Vehicle Speed Sensor Malfunc-
tion
Combination meter
Open or short in vehicle speed sensor circuit
Vehicle speed sensor
ECM

P0505
(DI±107)Idle Control System MalfunctionErectric throttle control system
Air induction system
*1: 


MIL lights up

± DIAGNOSTICSENGINE
DI±17
2001 PRIUS (RM778U)
MANUFACTURER CONTROLLED:
DTC No.
(See Page)Detection ItemTrouble AreaMIL*1Memory
P1125
(DI±108)Throttle Control Motor Circuit
MalfunctionOpen or short in throttle control motor circuit
Throttle control motor
ECM

P1127
(DI±110)ETCS Actuator Power Source
Circuit MalfunctionOpen in ETCS power source circuit
ECM
P1128
(DI±112)Throttle Control Motor Lock Mal-
functionThrottle control motor
Throttle body
P1129
(DI±114)Electric Throttle Control System
MalfunctionElectric throttle control system
ECM
P1300
(DI±115)Igniter Circuit Malfunction (No.1)
Ignition system
Open or short in IGF1 and IGT1 circuit from No.1 ignition coil
with igniter to ECM
No.1 ignition coil with igniter
ECM

P1305
(DI±115)Igniter Circuit Malfunction (No.2)
Ignition system
Open or short in IGF2 and IGT2 circuit from No.2 ignition coil
with igniter to ECM
No.2 ignition coil with igniter
ECM

P1310
(DI±115)Igniter Circuit Malfunction (No.3)
Ignition system
Open or short in IGF2 and IGT3 circuit from No.3 ignition coil
with igniter to ECM
No.3 ignition coil with igniter
ECM

P1315
(DI±115)Igniter Circuit Malfunction (No.4)
Ignition system
Open or short in IGF1 and IGT4 circuit from No.4 ignition coil
with igniter to ECM
No.4 ignition coil with igniter
ECM

P1346
(DI±120)VVT Sensor/Camshaft Position
Sensor Circuit Range/Perfor-
mance Problem (Bank 1)Mechanical system (Jumping teeth of timing belt, belt
stretched)
ECM

P1349
(DI±121)VVT System Malfunction (Bank
1)
Valve timing
OCV
VVT controller assembly
ECM

P1430
(DI±127)Vacuum Sensor for Adsorber
and Catalyst System Circuit Mal-
functionOpen or short circuit in vacuum sensor circuit
Vacuum sensor for HC adsorber and catalyst system
ECM

P1431
(DI±131)Vacuum Sensor for Adsorber
and Catalyst System CIrcuit
Rangel Performance ProblemVacuum sensor for HC adsorber and catalyst system
Vacuum line
P1436
(DI±133)Variable Value Malfunction
Vacuum line
Actuator for HC adsorber and catalyst system
Front exhaust pipe

P1437
(DI±135)Vacuum Line Malfunction
Vacuum line
VSV for HC adsorber and catalyst system
Check valve


DI±18
± DIAGNOSTICSENGINE
2001 PRIUS (RM778U)P1455
(DI±140)
Vapor Reducing Fuel Tank Sys-
tem Leak Detected (Small Leak)
Hose and pipe
Heated oxygen sensor
Fuel system
VVT system
Ignition system
Mass air flow meter
ECM

P1525
(DI±141)Resolver Circuit
MalfunctionHV ECU
Engine ECU±
P1600
(DI±143)ECM BATT MalfunctionOpen in back up power source circuit
ECM
P1633
(DI±145)ECU Malfunction (ETCS Circuit)ECM
P1636
(DI±146)HV ECU MalfunctionHV ECU
Engine ECU
P1637
(DI±148)EGSTP Signal MalfunctionHV ECU
Engine ECU±
P1656
(DI±150)OCV Circuit Malfunction (for
VVT±i)Open or short in OCV circuit
OCV
ECM

P3190
(DI±153)Poor Engine Power
Air induction system
Throttle body
Fuel pressure
Engine
Mass air flow meter

P3191
(DI±153)Engine dose not start
Mass air flow meter
Out of fuel
Engine coolant temp. sensor
Crankshaft position sensor
Camshaft position sensor
ECM
*1: 


MIL lights up

DI7SS±01
F02094
E7 E8 E9 E10
DI±20
± DIAGNOSTICSENGINE
2001 PRIUS (RM778U)
TERMINALS OF ECM
Symbols (Terminal No.)Wiring ColorConditionSTD Voltage (V)
BATT (E8 ± 3) ± E1 (E8 ± 17)R±W eBRAlways9 ± 14
+B (E8 ± 4) ± E1 (E8 ± 17)B e BRIG switch ON9 ± 14
+BM (E7 ± 6) ± E1 (E8 ± 17)GR e BRAlways9 ± 14
IGSW(E10 ± 9) ± E1(E8 ± 17)B±W e BRIG switch ON9 ± 14
MREL (E9 ± 25)
± E1(E8 ± 17)G±R e BRIG switch ON9 ± 14
VC (E8 ± 2) ± E2 (E8 ± 18)Y±R e BRIG switch ON4.5 ± 5.5
VTA (E8 23) E2 (E8 18)PBR
IG switch ON
Throttle valve fully closed0.4 ± 1.0
VTA (E8 ± 23) ± E2 (E8 ± 18)Pe BRIG switch ON
Throttle valve fully open3.2 ± 4.8
VTA2 (E8 21) E2 (E8 18)LBR
IG switch ON
Accelerator pedal released2.0 ± 2.9
VTA2 (E8 ± 21) ± E2 (E8 ± 18)Le BRIG switch ON
Accelerator pedal depressed4.6 ± 5.1
VG (E8 ± 10) ± EVG (E8 ± 19)G eRIdling, A/C switch OFF, Shift position in N or P position0.5 ± 3.0
THA (E8 ± 22) ± E2 (E8 ± 18)R±B eBRIdling, Intake air temp. 20°C (68°F)0.5 ± 3.4
THW (E8 ± 14) ± E2 (E8 ± 18)W eBRIdling, Engine coolant temp. 80°C (176°F) 0.2 ± 1.0
IG switch ON9 ± 14
#10 (E8 ± 5) ± E01 (E7 ± 21)Y eW±BIdlingPulse generation
(See page DI±65)
IG switch ON9 ± 14
#20 (E8 ± 6) ± E01 (E7 ± 21)B±R eW±BIdlingPulse generation
(See page DI±65)
IG switch ON9 ± 14
#30 (E7 ± 1) ± E01 (E7 ± 21)L±W eW±BIdlingPulse generation
(See page DI±65)
IG switch ON9 ± 14
#40 (E7 ± 2) ± E01 (E7 ± 21)R±W eW±BIdlingPulse generation
(See page DI±65)
IGT1 (E7 ± 11) ± E1 (E8 ± 17)Y±G eBRIdlingPulse generation
(See page DI±115)
IGT2 (E7 ± 12) ± E1 (E8 ± 17)W eBRIdlingPulse generation
(See page DI±115)
IGT3 (E7 ± 13) ± E1 (E8 ± 17)G eBRIdlingPulse generation
(See page DI±115)

± DIAGNOSTICSENGINE
DI±21
2001 PRIUS (RM778U) IGT4 (E7 ± 14) ± E1 (E8 ± 17)
Y eBRIdlingPulse generation
(See page DI±115)
IG switch ON4.5 ± 5.5
IGF (E7 ± 25) ± E1 (E8 ± 17)B±R eBRIdlingPulse generation
(See page DI±115)
G2 (E7 ± 10) ± NE
(E8 ± 24)R eGIdlingPulse generation
(See page DI±74)
NE+ (E8 ± 16) ± NE± (E8 ± 24)R eGIdlingPulse generation
(See page DI±74)
FC (E8 ± 9) ± E01 (E7 ± 21)G±R eW±BIG switch ON9 ± 14
EVP1 (E7 ± 29) ± E1 (E8 ± 17)R±L eBRIG switch ON9 ± 14
OX1A (E10 ± 12) ± E2 (E8 ±
18)W eBRMaintain engine speed at 2,500 rpm for 2 min. after
warming upPulse generation
(See page DI±44)
OX1B (E10 ± 11)
± E2 (E8 ± 18)Y eBRMaintain engine speed at 2,500 rpm for 2 min. after
warming upPulse generation
(See page DI±44)
HT1A (E10 1) E1 (E8 17)PLBRIdlingBelow 3.0HT1A (E10 ± 1) ± E1 (E8 ± 17)P±L eBRIG switch ON9 ± 14
HT1B (E10 7) E1 (E8 17)GYBRIdlingBelow 3.0HT1B (E10 ± 7) ± E1 (E8 ± 17)G±Y eBRIG switch ON9 ± 14
KNK1 (E7 ± 28) ± E2 (E8 ± 18)B eBRIdlingPulse generation
(See page DI±71)
SPD (E10 ± 5)
± E1 (E8 ± 17)V±W eBRIG switch ON
Rotate driving wheel slowlyPulse generation
SPHV (E9 ± 10)
± E1 (E8 ± 17)O eBRIG switch ON
Rotate driving wheel slowlyPulse generation
(See page DI±105)
ESTP (E9 ± 16) ± E1 (E8 ± 17)R±Y eBRIdling9 ± 14
TAM (E9 ± 23) ± E2 (E8 ± 18)W±G eBROuter air temp. ±30 ± 50°C0.7 ± 3.2
W (E10 6) E1 (E8 17)GRBRIdling9 ± 14W (E10 ± 6) ± E1 (E8 ± 17)G±R eBRIG switch ONBelow 3.0
ACT (E10 22) E1 (E8 17)PGBRA/C switch OFFBelow 2.0ACT (E10 ± 22) ± E1 (E8 ± 17)P±G eBRA/C switch ON at idling9 ± 14
OCV+ (E7 ± 23)YRWGIG it h ONPulse generationOCV+ (E7 23)
± OCV ± (E7 ± 24)Y±R eW±GIG switch ONPulse generation
(See page DI±121)
M+ (E7 ± 8) ± E1 (E8 ± 17)
M± (E7 ± 7) ± E1 (E8 ± 17)L eBR
P eBRIdlingPulse generation
(See page DI±108)
TC (E9 ± 6) ± E1 (E8 ± 17)P±B eBRIG switch ON9 ± 14
HCC (E9 ± 20) ± E1 (E8 ± 17)B±W e BRIG switch ON9 ± 14
PTNK (E9 ± 22) LRBRIG switch ON9 ± 14PTNK (E9 22)
± E1 (E8 ± 17)L±R e BRApply vacuum 4.0 kPa (30 mmHg, 1.2 in.Hg)Below 0.5
HCLS (E9 ± 14) VWBRIG switch ON3.3 ± 3.9HCLS (E9 14)
± E1 (E8 ± 17)V±W e BRApply vacuum 67 kPa (500 mmHg, 19.7 in.Hg)1.3 ± 1.9

DI6UV±03
A06106
B+
Temparature Sensor
Power Transister
Platinum Hot wire
B
Output A
Voltage
FI6929
S05741
± DIAGNOSTICSENGINE
DI±23
2001 PRIUS (RM778U)
CIRCUIT INSPECTION
DTC P0100 Mass Air Flow Circuit Malfunction
CIRCUIT DESCRIPTION
The mass air flow meter uses a platinum hot wire. The hot wire air flow meter consists of a platinum hot wire,
temparature sensor and a control circuit installed in a plastic housing. The hot wire air flow meter works on
the principle that the hot wire and temparature sensor located in the intake air bypass of the housing detect
any changes in the intake air temp.
The hot wire is maintained at the set temp. by controlling the current flow through the hot wire. This current
flow is then measured as the output voltage of the air flow meter.
The circuit is constructed so that the platinum hot wire and temparature sensor provide a bridge circuit,with
the power transistor controlled so that the potential of A and B remains equal to maintain the set temp.
DTC No.DTC Detecting ConditionTrouble Area
P0100Open or short in mass air flow meter circuit with more than 3
sec. engine speed 3,000 rpm or less
Open or short in mass air flow meter circuit

Mass air flow meter

ECM
If the ECM detects DTC ºP0100º it operates the fail±safe function, keeping the ignition timing and injection
volume constant and making it possible to drive the vehicle.
HINT:
After confirming DTC P0100 use the OBD II scan tool or TOYOTA hand±held tester to confirm the mass air
flow ratio from ºCURRENT DATAº.
Mass Air Flow Value (gm/sec.)Malfunction
0.0
Mass air flow meter power source circuit open

VG circuit open or short
271.0 or more
E2G circuit open

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