Toyota Sequoia (2005). Manual - part 116

A23480

Fuel Tank

Canister

Vacuum Pump: OFF

Pressure Sensor

0.02 Inch Orifice

Pump Module

Operation A: Atmospheric Pressure Measurement

Vent Valve: OFF (vent)

Operation D: Purge VSV monitor

Operation B, E: 0.02 Inch Leak Pressure Measurement

Negative
Pressure

Atmospheric
Pressure

Air Filter

Purge VSV: OFF

OFF (vent)

ON

OFF

OFF

ON

ON (closed)

ON

ON

ON (closed)

Operation C: EVAP System Pressure Measurement

A23483

Purge VSV

Vent Valve

Vacuum Pump

EVAP Pressure

Positive

Leak Pressure

sec

Negative

ON

ON

Sequence

Time

A

10

sec

60

Within 15 minutes

sec

ON

First 0.02 inch

B

C

D

OK

Malfunction

ON: Open
OFF: Closed

OFF: Vent

ON: Closed

10

Standard

sec

60

E

EVAP Pressure when Purge VSV Stuck Open:

Leak Pressure

Second 0.02 inch

Standard x 0.2

–

DIAGNOSTICS

ENGINE

DI–259

453

(a)

Purge VSV stuck open

In operation C, the vacuum pump creates negative pressure (vacuum) in the EVAP (Evaporative Emission)
system. The EVAP system pressure is then measured by the ECM using the pressure sensor. If the stabilized
system pressure is higher than [second 0.02 inch leak pressure standard x 0.2], the ECM interprets this as
the purge VSV (Vacuum Switching Valve) being stuck open. The ECM illuminates the MIL and sets the DTC
(2 trip detection logic).

A23484

Purge VSV

Vent Valve

Vacuum Pump

EVAP Pressure

Positive

Leak Pressure

sec

Negative

ON

ON

Sequence

Time

A

10

sec

60

Within 15 minutes

ON

First 0.02 inch

B

C

D

OK

Malfunction

ON: Open
OFF: Closed

OFF: Vent

ON: Closed

10

Standard

sec

60

E

EVAP Pressure when Purge VSV Stuck Closed:

A23485

EVAP Pressure
During Purge Flow Monitor:

VSV

EVAP 
Pressure

Open

1st

Monitor

2nd

Monitor

ON (closed)

Purge

Valve

Vent

OK

OK

Malfunction

0.1 kPa

0.5 kPa

DI–260

–

DIAGNOSTICS

ENGINE

454

(b)

Purge VSV stuck closed

In operation D, the pressure sensor measures the EVAP system pressure. The pressure measurement for
purge VSV monitor is begun when the purge VSV is turned ON (open) after the EVAP leak check. When
the measured pressure indicates an increase of 0.3 kPa (2.25 mmHg) or more, the purge VSV is functioning
normally. If the pressure does not increase, the ECM interprets this as the purge VSV being stuck closed.
The ECM illuminates the MIL and sets the DTC (2 trip detection logic).

2.

PURGE FLOW MONITOR

The purge flow monitor consists of the two step monitors. The
1st monitor is conducted every time and the 2nd monitor is acti-
vated if necessary.

The 1st monitor 
While the engine is running and the purge VSV
(Vacuum Switching Valve) is ON (open), the ECM
monitors the purge flow by measuring the EVAP
pressure change. If negative pressure is not
created, the ECM begins the 2nd monitor.

The 2nd monitor 
The vent valve is turned ON (closed) and the EVAP
pressure is then measured. If the variation in the
pressure is less than 0.5 kPa (3.75 mmHg), the
ECM interprets this as the purge VSV being stuck
closed, and illuminates the MIL and sets DTC
P0441 (2 trip detection logic).

Atmospheric pressure check: 
In order to ensure reliable malfunction detection, the variation
between the atmospheric pressures, before and after conduc-
tion of the purge flow monitor, is measured by the ECM.

–

DIAGNOSTICS

ENGINE

DI–261

455

MONITOR STRATEGY

Purge VSV stuck open

Related DTCs

P0441

Purge VSV stuck closed

Related DTCs

P0441

Purge flow

Required sensors/components

Purge VSV, Pump module

Frequency of operation

Once per driving cycle

Duration

Purge VSV stuck open and closed: Within 2 min. (varies with amount of fuel in tank)

Purge flow: Within 30 sec.

MIL operation

2 driving cycle

Sequence of operation

None

TYPICAL ENABLING CONDITIONS

It

Specification

Item

Minimum

Maximum

The monitor will run whenever these

DTCs are not present

See page 

DI–18

Purge VSV stuck open and closed:

Following values are when atmospheric is

760 mmHg (100 kPa)

–

EVAP key–off monitor runs when all of the

following conditions met:

–

Atmospheric pressure

525 to 825 mmHg (70 to 110 kPa)

Battery voltage

10.5 V

–

Vehicle speed

–

4 km/h (2.5 mph)

Ignition switch

OFF

Engine condition

Not running

Time after engine stopped

5 hours

FTP sensor malfunction (P0450, P0452,

P0453)

Not detected

Purge VSV

Not operated by scan tool

Vent valve

Not operated by scan tool

Leak detection pump

Not operated by scan tool

Both of the following conditions are met

before IG switch OFF

Condition 1 and 2

1. Duration that vehicle is driven

5 min.

–

2. Purge flow

Executed

ECT

4.4 to 35

°

C (40 to 95

°

F)

IAT

4.4 to 35

°

C (40 to 95

°

F)

Example of re–start time

–

First time

7 hours

Second time

9 hours and 30 min.

Key–off monitor sequence

1 to 8

1. Atmospheric pressure

–

Next sequence is run if following condition

set

–

Atmospheric pressure change for 10 sec.

–

2.25 mmHg (0.3 kPa) for 1 sec.

2. First reference pressure

–

DI–262

–

DIAGNOSTICS

ENGINE

456

Next sequence is run if all of following

conditions set

Condition 1, 2 and 3

1. FTP when 4 sec. after reference pres-

sure measurement

–

–7.5 mmHg (–1 kPa)

2. Reference pressure

–36.38 to –7.93 mmHg (–4.85 to –1057 kPa)

3. Reference pressure

Saturated

3. Vent valve stuck closed check

–

Next sequence is run if following condition

set

–

FTP change for 10 sec. after vent valve

ON (closed)

2.25 mmHg (0.3 kPa)

–

4. Vacuum introduction and leak

–

Next sequence is run if both of following

conditions set

Condition 1 and 2

1. Vacuum introduction time

–

15 min.

2. FTP

FTP was saturated

5. Purge VSV stuck closed check

–

Next sequence is run if following condition

set

–

FTP change for 10 sec. after purge VSV

ON (open)

2.25 mmHg (0.3 kPa)

–

6. Second reference pressure measure-

ment

–

Next sequence is run if all of following

conditions set

Condition 1, 2, 3 and 4

1. FTP when 4 sec. after reference pres-

sure measurement

–

–7.5 mmHg (–1 kPa)

2. Reference pressure

–36.38 to –7.93 mmHg (–4.85 to –1057 kPa)

3. Reference pressure

Saturated

4. Reference pressure difference between

first and second

–

5.25 mmHg (0.7 kPa)

7. Leak check

–

Next sequence is run if following condition

set

–

FTP when vacuum introduction was com-

plete

–

Second reference pressure

8. Atmospheric pressure

–

Monitor is complete if following

–

Atmospheric pressure difference between

sequence 1 and 8

–

2.25 mmHg (0.3 kPa)

Purge flow:

Engine condition

Running

ECT

4.4

°

C (40

°

F)

–

IAT

4.4

°

C (40

°

F)

–

FTP sensor malfunction

Not detected

Purge VSV

Not operated by scan tool

EVAP system check

Not operated by scan tool