Toyota Sequoia (2005). Manual - part 167

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DIAGNOSTICS

ENGINE

DI–463

657

Components

Operations

Canister

Contains activated charcoal to absorb EVAP (Evaporative Emissions) generated in fuel tank.

Cut–off valve

Located in fuel tank. Valve floats and closes when fuel tank is 100 % full.

Purge VSV (Vacuum
Switching Valve)

Opens or closes line between canister and intake manifold. ECM uses purge VSV to control EVAP purge flow. In order
to discharge EVAP absorbed by canister to intake manifold, ECM opens purge VSV. EVAP discharge volume to intake
manifold controlled by purge VSV duty cycle ratio (current–carrying time). (Open: ON, Close: OFF)

Refueling valve

Controls EVAP pressure from fuel tank to canister. Valve consists of diaphragm, spring and restrictor (diameter: 0.08
inch). When fuel vapor and pressure inside fuel tank increase, valve opens. While EVAP purged, valve closes and re-
strictor prevents large amount of vacuum from affecting pressure in fuel tank. Valve opened while refueling. When valve
open, adding fuel into fuel tank possible.

Roll–over valve

Located in fuel tank. Valve closes by its own weight when vehicle overturns to prevent fuel from spilling out.

Service port

Used for connecting vacuum gauge for inspecting EVAP system.

Soak timer

Built into ECM. To ensure accurate EVAP monitor, measures 5 hours

*

 after ignition switch turned to OFF. This allows

fuel to cool down, stabilizing Fuel Tank Pressure (FTP). When approx. 5 hours

*

 elapsed, ECM activates.

Pump module

Consists of (a) to (d) below. Pump module cannot be disassembled.

(a) Vent valve

Vents and closes EVAP system. When ECM turns valve ON, EVAP system closed. When, ECM turns valve OFF, EVAP
system vented. Negative pressure (vacuum) created in EVAP system to check for EVAP leaks by closing purge VSV,
turning on vent valve (closed) and operating vacuum pump (refer to fig. 1).

(b) Pressure sensor

Indicates pressure as voltages. ECM supplies regulated 5 V to pressure sensor, and uses feedback from sensor to
monitor EVAP system pressure (refer to fig 2).

(c) Vacuum pump

Creates negative pressure (vacuum) in EVAP system for leak check.

(d) 0.02 inch orifice

Has opening with 0.02 inch diameter. Vacuum produced through orifice by closing purge VSV, turning off vent valve and
operating vacuum pump, to monitor 0.02 inch leak pressure. 0.02 inch leak pressure indicates small leak of EVAP.

HINT:
*:If the engine coolant temperature is not below 35



C after 5 hours after the ignition switch is turned off, the

monitor check starts 2 hours later. If it is still not below 35



C 7 hours after the ignition switch is turned off,

the monitor check starts 2.5 hours later.

A23494

Pump Module (fig. 1):

Condition: Purge Flow

Condition: Leak Check

From Refueling Valve

To Air Filter
(Atmosphere)

Vacuum Pump: OFF

Vent Valve: OFF
(vent)

Pressure Sensor

0.02 Inch Orifice

Canister

: Airflow

Vacuum Pump: ON

Vent Valve: ON
(closed)

A23495

Pressure Sensor Specification (fig. 2)

Output Voltage

Usable Range

4.900 V

4.150 V

1.425 V

0.450 V

Malfunction Area

Pressure

60
kPa

110
kPa

Malfunction Area

Standard atmospheric pressure is 101.3 kPa

HINT:

A23496

Soak Timer Circuit (fig. 3)

Ignition Switch

IGSW

Power

ECM

EFI MAIN

MREL

+B

15 A

Source IC

Soak Timer IC

Main Relay
Control IC

Battery

DI–464

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DIAGNOSTICS

ENGINE

658

A23565

L5 
Pump Module

Pressure Sensor

Vacuum Pump

Vent Valve

Engine Room R/B

Battery

J/C

V4
Purge 
VSV

VC

PPMP

E2

MPMP

VPMP

PRG

MREL

EFI Relay

F10
FL Block

5

4

B

B

EFI No.1

2D

1

5

3

EFI No.2

2A

2

4

1

8

9

3

2

G–R

A

A

J/C J2

G–R

G–R

G–R

G–R

IA4

4

J/C J16

B

B

B

J/C

IG4

22

G–R

W–G

E8

34

B–W

E6

8

B–W

IA4

14

2H

6

2

1

2F

1

W–B

J/C J5

A

J48

J49

F

L

G–R

BB1

2

G–R

G–R

BN1

5

P–L

BN1

BN1

BN1

BN1

BN1

P–L

6

BB1

8

P–L

P–L

J49

J48

B

H

E4

5

6

V–G

J48

K

J49

E

V–G

BB1

7

V–G

V–G

4

G–W

3

G–W

BB2

4

G–W

IJ3

3

G–W

IG4

6

G–W

E8

28

22

E4

E4

R–G

IJ3

4

R–G

BB2

2

R–G

2

R–G

G–B

1

G–B

BB2

3

G–B

IJ3

14

G–B

IG4

7

G–B

E8

23

BN1 8

W–B

W–B

BI

ED

ECM

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DIAGNOSTICS

ENGINE

DI–465

659

WIRING DIAGRAM

0.02 inch orifice clogged

Pressure sensor voltage low

P043E

P043F

P0441

P0451

P0452

P0453

P0455

P0456

P2419

P2401

P2402

0.02 inch orifice high–flow

Pressure sensor stuck

Pressure sensor noising

Gross leak

Small leak

Vacuum pump stuck OFF

Vacuum pump stuck ON

Vent valve stuck ON (closed)

Vent valve stuck OFF (vent)

Purge VSV stuck open

Purge VSV stuck closed

Pressure sensor voltage high

DTCs

Malfunctioning Areas

P2420

P0450

DI–466

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DIAGNOSTICS

ENGINE

660

INSPECTION PROCEDURE

NOTICE:
A hand–held tester is required to conduct the following diagnostic troubleshooting procedure.
HINT:

Using hand–held tester monitor results enables the EVAP (Evaporative Emission) system to be con-
firmed.

Read freeze frame data using a hand–held tester Freeze frame data record the engine condition when
malfunctions are detected. When troubleshooting, freeze frame data can help determine if the vehicle
was moving or stationary, if the engine was warmed up or not, if the air–fuel ratio was lean or rich, and
other data, from the time the malfunction occurred.

1

Confirm DTC.

(a)

Turn the ignition switch to OFF and wait for 10 seconds.

(b)

Turn the ignition switch to ON.

(c)

Turn the ignition switch to OFF and wait for 10 seconds.

(d)

Connect a hand–held tester to the DLC3.

(e)

Turn the ignition switch to ON and turn the tester ON.

(f)

Select the following menu items: DIAGNOSIS / ENHANCED OBD II / DTC INFO / CURRENT CODES.

(g)

Confirm DTCs and freeze frame data.

If any EVAP system DTCs are set, the malfunctioning area can be determined using the table below.

NOTICE:
If the 0.02 inch reference pressure difference between the first and second checks is greater than
the specification, the DTCs corresponding to the reference pressure (P043E, P043F, P0441, P0455,
P0456, P2401, P2420) will be all stored.

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