Page 2561 of 4770
± DIAGNOSTICSENGINE (5S±FE)
DI±141
376 Author: Date:
10 Check operation of VSV for vapor pressure sensor (See page SF±47).
NG Go to step 11.
OK
Replace VSV and clean vacuum hoses between charcoal canister and VSV for vapor pressure
sensor, and VSV for vapor pressure sensor and vapor pressure sensor, and then check the char-
coal canister.
11 Check for open and short in harness and connector between EFI main relay
(Marking: EFI) and VSV for vapor pressure sensor, and VSV for vapor pressure
sensor and ECM (See page IN±31).
NG Repair or replace harness or connector.
OK
Check and replace ECM (See page IN±31).
12 Check fuel tank over fill check valve (See page EC±6).
NG Replace fuel tank over fill check valve or fuel
tank.
OK
Check and replace charcoal canister
(See page EC±6).
Page 2562 of 4770
A06551
VSV for
EVAP
Charcoal Canister
Fuel Tank ECM
Vapor Pressure
Sensor
VSV for Vapor
Pressure Sensor
Fuel Tank Over
Fill Check Valve
DI±142
± DIAGNOSTICSENGINE (5S±FE)
377 Author: Date:
DTC P0450 Evaporative Emission Control System
Pressure Sensor Malfunction
DTC P0451 Evaporative Emission Control System
Pressure Sensor Range/Performance
CIRCUIT DESCRIPTION
The vapor pressure sensor and VSV for vapor pressure sensor are used to detect abnormalities in the evap-
orative emission control system.
The ECM decides whether there is an abnormality in the evaporative emission control system based on the
vapor pressure sensor signal.
DTC P0450 is recorded by the ECM when the vapor pressure sensor malfunction.
DI1K0±04
Page 2563 of 4770

± DIAGNOSTICSENGINE (5S±FE)
DI±143
378 Author: Date:
DTC No.DTC Detecting ConditionTrouble Area
P0450
10 seconds or more after engine starting codition (a) or (b)
continues for 7 seconds or more:
(2 trip detection logic)
(a) vapor pressure sensor value < ±4 kpa (±30 mmHg,
±1.0 in.Hg)
(b) Vapor pressure sensor value 2.1 kpa (±15 mmHg,
0.4 in.Hg)
Open or short in vapor pressure sensor circuit
Vapor pressure sensor
ECM
F l t k fill h k l k d d d
P0451
Vapor pressure sensor output extremely changes under condi-
tions of (a), (b) and (c):
(2 trip detection logic)
(a) Vehicle speed: 0 km/h (0 mph)
(b) Engine speed: idling
(c) VSV for vapor pressure sensor is ONFuel tank over fill check valve cracked or damaged.
WIRING DIAGRAM
Refer to DTC P0440 (Evaporative Emission Control System Malfunction) on page DI±122.
INSPECTION PROCEDURE
HINT:
If DTC P0441 (Evaporative Emission Control System Incorrect Purge Flow), P0446 (Evaporative
Emission Control System Vent Control Malfunction), P0450 (Evaporative Emission Control System
Pressure Sensor Malfunction) or P0451 is output after DTC P0440 (Evaporative Emission Control Sys-
tem Malfunction), first troubleshoot DTC P0441, P0446, P0450 or P0451. If no malfunction is detected,
troubleshoot DTC P0440 next.
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.
When the ENGINE RUN TIME in the freeze frame data is less than 200 seconds, carefully check the
VSV for EVAP, charcoal canister and vapor pressure sensor.
1 Check voltage between terminals VC and E2 of ECM connector
(See page DI±122, step 9).
NG Check and replace ECM (See page IN±31).
OK
Page 2564 of 4770
DI±144
± DIAGNOSTICSENGINE (5S±FE)
379 Author: Date:
2 Check voltage between terminals PTNK and E2 of ECM connector
(See page DI±122, step 10 ).
OK Check and replace ECM (See page IN±31).
NG
3 Check for open and short in harness and connector between the vapor pressure
sensor and ECM (See page IN±31).
NG Repair or replace harness or connector.
OK
Replace vapor pressure sensor.
Page 2565 of 4770

A00414
No.1 Vehicle
Speed Sensor4±Pulse 4±Pulse
Combination Meter
ECM
Transaxle
No.1 Vehicle Speed Sensor
A03601
Combination Meter
14
V±WV±W
B J15
J/C
IG3
BV±W9
E7SPD5 V ECM
3
C9
*1: w/o Immobiliser
*2: w/ Immobiliser(*1) (*2)
E7 8
± DIAGNOSTICSENGINE (5S±FE)
DI±145
380 Author: Date:
DTC P0500 Vehicle Speed Sensor Malfunction
CIRCUIT DESCRIPTION
The No.1 vehicle speed sensor outputs a 4±pulse signal for every revolution of the rotor shaft, which is ro-
tated by the transmission output shaft via the driven gear. After this signal is converted into a more precise
rectangular waveform by the waveform shaping circuit inside the combination meter, it is then transmitted
to the ECM. The ECM determines the vehicle speed based on the frequency of these pluse signals.
DTC No.DTC Detecting ConditionTrouble Area
P0500
During vehicle is being driven, no vehicle speed sensor signal
to ECM
(2 trip detection logic)Combination meter
Open or short in No.1 vehicle speed sensor circuit
No.1 vehicle speed sensor
ECM
WIRING DIAGRAM
DI01B±10
Page 2566 of 4770
DI±146
± DIAGNOSTICSENGINE (5S±FE)
381 Author: Date:
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 Check operation of speedometer.
CHECK:
Drive the vehicle and check if the operation of the speedmeter in the combination meter is normal.
HINT:
The vehicle speed sensor is operating normally if the speedometer display is normal.
NG Check speedometer circuit. See combination
meter troubleshooting (See page BE±2).
OK
Page 2567 of 4770
A03021
A03425
ON
SP1
(+)
SP1
(+)
w/o Immobiliser
w/ Immobiliser
AT7809
4.5 ~ 5.5 V
0
Turn the wheel
± DIAGNOSTICSENGINE (5S±FE)
DI±147
382 Author: Date:
2 Check voltage between terminal SPD of ECM connector and body ground.
PREPARATION:
(a) Remove the glove compartment (See page SF±64).
(b) Shift the shift lever to neutral.
(c) Jack up one of the front wheels.
(d) Turn the ignition switch ON.
CHECK:
Measure voltage between terminal SPD of ECM connector and
body ground when the wheel is turned slowly.
OK:
Voltage is generated intermittently.
NG Check and repair harness and connector
between combination meter and ECM.
OK
Check and replace ECM (See page IN±31).
Page 2568 of 4770

P01559
Throttle Valve
To Cylinder ECM Signal From
Air
Cleaner
Valve
IAC Valve
Intake Air
Chamber
A07553
B±Y 9
2B±Y B±Y
II3J19
J/CIAC ValveECM
1
3 2
B
EFI
5
1 Engine Room J/B No.2
42
2J
W±B
B
ISCO
E01
E01 ISCC10
9W
B±OE9
E9
1
2A
2K
EFI Relay
EB
From
BatteryB
*1: w/o Immobiliser
*2: w/ Immobiliser(*1) (*2)
E97
E96
(*2) (*1)
E107MREL2FB±W B±W
II4
(*2)
7
6(*2) (*2)
3
B±R
(*1)From
Ignition SW DI±148
± DIAGNOSTICSENGINE (5S±FE)
383 Author: Date:
DTC P0505 Idle Control System Malfunction
CIRCUIT DESCRIPTION
The rotary solenoid type IAC valve is located on the throttle
body and intake air bypassing the throttle valve is directed to
the IAC valve through a passage.
In this way the intake air volume bypassing the throttle valve is
regulated, controlling the engine speed.
The ECM operates only the IAC valve to perform idle±up and
provide feedback for the target idling speed.
DTC No.DTC Detecting ConditionTrouble AreaTrouble Area
P0505Idle speed continues to vary greatly from the target speed
(2 trip detection logic)
IAC valve is stuck or closed
Open or short in IAC valve circuit
Open or short in A/C switch circuit
Air intake (hose loose)
ECM
WIRING DIAGRAM
DI01C±05