Lexus ES300 (1997 year). Manual - part 331

A00233

OFF

EVP1

ON

ON

VSV is ON

VSV is OFF

BE6653
S01097
P24973
P24974

Air

F

Air

F

E

E

–

DIAGNOSTICS

ENGINE

DI–101

253

1997 LEXUS ES300   (RM511U)

5

Check for open and short in harness and connector between vapor pressure
sensor and ECM (See page 

IN–27

).

NG

 Repair or replace harness or connector.

OK

Replace vapor pressure sensor.

6

Check VSV for EVAP.

PREPARATION:
(a)

Remove the glove compartment (See page 

SF–65

).

(b)

Turn ignition switch ON.

CHECK:
Check VSV function.

(1)

Connect between terminal EVP1 of ECM and body
ground.

(2)

Disconnect between terminal EVP1 of ECM and
body ground.

OK:

(1) VSV is ON:  
Air from pipe E is flowing out through pipe F.
(2) VSV is OFF:  
Air does not flow from pipe E to pipe F.

OK

 Go to step 9.

NG

7

Check operation of VSV for EVAP (See page 

SF–52

).

NG

 Replace VSV for EVAP.

OK

A00234

ON

ON

TPC

OFF

VSV is OFF

VSV is ON

Air

Air

F

F

E

E

G

G

DI–102

–

DIAGNOSTICS

ENGINE

254

1997 LEXUS ES300   (RM511U)

8

Check for open and short in harness and connector between EFI main relay
(Marking: EFI) and VSV for EVAP and ECM (See page 

IN–27

).

NG

 Repair or replace harness or connector.

OK

Check and replace ECM (See page 

IN–27

).

9

Check VSV for vapor pressure sensor.

PREPARATION:
(a)

Remove the glove compartment (See page 

SF–65

).

(b)

Turn ignition switch ON.

CHECK:
Check VSV function.

(1)

Connect between terminal TPC of ECM and body
ground (ON).

(2)

Disconnect between terminal TPC of ECM and
body ground (OFF).

OK:

(1) VSV is ON:
Air from pipe E is flowing out through pipe F.
(2) VSV is OFF:
Air from pipe E flows out through pipe G.

OK

 Check and replace charcoal canister
(See page 

EC–5

).

NG

–

DIAGNOSTICS

ENGINE

DI–103

255

1997 LEXUS ES300   (RM511U)

10

Check operation of VSV for vapor pressure sensor (See page 

SF–56

).

NG

 Replace VSV for vapor pressure sensor.

OK

11

Check for open and short in harness and connector between EFI main relay
(Marking: EFI) and VSV for vapor pressure sensor and ECM (See page 

IN–27

).

NG

 Repair or replace harness or connector.

OK

Check and replace ECM (See page 

IN–27

).

S00042

Charcoal Canister

Vapor Pressure
Sensor

VSV for Vapor

Fuel Tank

VSV 
for EVAP

Pressure Sensor

ECM

DI–104

–

DIAGNOSTICS

ENGINE

256

1997 LEXUS ES300   (RM511U)

DTC

P0450

Evaporative Emission Control System 
Pressure Sensor Malfunction

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.

DTC No.

DTC Detecting Condition

Trouble Area

P0450

10 seconds or more after engine starting condition (a) or (b)

continues for 7 seconds or more:

(2 trip detection logic)

(a) Vapor Pressure Sensor Value 

 –3.5 kPa (–26 mmHg,

   –1.0 in.Hg)

(b) Vapor Pressure Sensor Value 



 1.5 kPa (11 mmHg,

     0.4 in.Hg)

Open or short in vapor pressure sensor circuit

Vapor pressure sensor

ECM

WIRING DIAGRAM

Refer to DTC P0440 on page 

DI–87

 for the WIRING DIAGRAM.

DI09X–01