Lexus ES300 (2002 year). Service manual - part 373

-

DIAGNOSTICS

SFI SYSTEM (1MZ-FE)

05-1 11

264

22

CHECK FUEL TANK OVER FILL CHECK VALVE

NG

REPLACE FUEL TANK OVER FILL CHECK
VALVE OR FUEL TANK

OK

REPAIR OR REPLACE CHARCOAL CANISTER ASSY

VSV for
CCV

VSV
for EVAP

ECM

Vapor Pressure Sensor

Fuel Tank Over
Fill Check Valve

Fuel Tank

Charcoal Canister

VSV for
Pressure
Switching Valve

A10145

05-1 12

-

DIAGNOSTICS

SFI SYSTEM (1MZ-FE)

265

2002 LEXUS ES300 REPAIR MANUAL   (RM911U)

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,

 

VSV for canister closed valve (CCV) and VSV for pressure switching valve are

used to detect abnormalities in the evaporative 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 or P0451 is recorded by the ECM when the vapor pressure sensor malfunction.

DTC No.

DTC Detecting Condition

Trouble Area

P0450

10 seconds or less after engine starting condition vapor pres-
sure sensor fixed value continues for fixed value or more: (2
trip detection logic)

P0451

Vapor pressure sensor output extremely changes under condi-
tions of (a) and (b): (2 trip detection logic)

(a) Vehicle speed: 0 km/h (0mph), Engine speed: Idling and

VSV for pressure switching valve is OFF

(b) vavor pressure sensor value 

 opening pressure valve of

charcoal canister

Open or short in vapor pressure sensor circuit

Vapor pressure sensor

ECM

WIRING DIAGRAM

Refer to DTC P0440 on page 

05-88

 .

051MD-08

A53763

VC

E2

A53769

E2

PTNK

-

DIAGNOSTICS

SFI SYSTEM (1MZ-FE)

05-1 13

266

2002 LEXUS ES300 REPAIR MANUAL   (RM911U)

INSPECTION PROCEDURE

HINT:

If DTC P0441, P0446, P0450 or P0451 is output after DTC P0440 or P0442, first trouble shoot DTC
P0441, P0446 P0450 or P0451. If no malfunction is detected, troubleshoot DTC P0440 or P0442 next.

Read freeze frame data using 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 deter-
mining whether the vehicle was running or stopped, the engine was warmed up or not, the air-fuel ratio
was 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

INSPECT ECM

(a)

Turn the ignition switch ON.

(b)

Measure the voltage between terminals VC and E2 of the
ECM connector.
Voltage: 4.5 - 5.5 V

NG

CHECK AND REPLACE ECM

OK

2

INSPECT ECM

(a)

Remove the fuel tank cap.

(b)

Turn the ignition switch ON.

(c)

Measure the voltage between terminals PTNK of the
ECM E6 connector and E2 of the ECM E10 connector.
Voltage: 3.0 - 3.6 V

OK

CHECK AND REPLACE ECM

NG

3

CHECK HARNESS AND CONNECTOR(VAPOR PRESSURE SENSOR - ECM)

NG

REPAIR OR REPLACE HARNESS AND
CONNECTOR

OK

REPLACE VAPOR PRESSURE SENSOR ASSY

From
Speed Sensor

Skid 
Control 
Computer 
ASSY

4-Pulse

Combination
Meter

ECM

4-Pulse

A52996

A61591

Combination Meter

33

Passenger Side J/B

6

V - W

C7

W

3A

IK1

17
E7

SPD

5V

V - W

3A

82

92

ECM

05-1 14

-

DIAGNOSTICS

SFI SYSTEM (1MZ-FE)

267

2002 LEXUS ES300 REPAIR MANUAL   (RM911U)

DTC

P0500

VEHICLE SPEED SENSOR MALFUNCTION

CIRCUIT DESCRIPTION

The speed sensor for skid control computer assy detects the wheel speed amd sends the appropriate signals
to the skid control computer assy.
The ECM converts these signals into a 4-pulse signal and outputs it to the combination meter.
After this signal is converted into a more precise rectangular waveform by the waveform shaping circuit in-
side the combination meter,it is then transmitted to the ECM. The ECM determines the vehicle speed based
on the frequency of these pulse signals.

DTC No.

DTC Detecting Condition

Trouble Area

P0500

No vehicle speed sensor signal to Engine & ECT ECU under
the following conditions: (2 trip detection logic)

Vehicle is being driven

Clutch or brake slips or gear is broken (2-trip detection logoc)

Combination meter

Open or short in speed sensor circuit

Vehicle speed  sensor

ECM

Skid control computer assy

WIRING DIAGRAM

055CI-04