TOYOTA SEQUOIA 2001 Service Repair Manual

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: OFFOFF (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 NegativeONON
Sequence
TimeA
10
sec60
Within 15 minutes
sec ON
First 0.02 inch
BCD
OK Malfunction
ON: Open
OFF: Closed
OFF: Vent ON: Closed
10
Standard
sec60
E EVAP Pressure when Purge VSV Stuck Open:
Leak PressureSecond 0.02 inch
Standard x 0.2
± DIAGNOSTICSENGINE
DI±259
453 Author: Date:
2005 SEQUOIA (RM1146U)
(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 NegativeONON
Sequence
TimeA
10
sec60
Within 15 minutesON
First 0.02 inch
BCD
OK
Malfunction
ON: Open
OFF: Closed
OFF: Vent ON: Closed
10
Standard
sec60
E EVAP Pressure when Purge VSV Stuck Closed:
A23485
EVAP Pressure
During Purge Flow Monitor:
VSV
EVAP
PressureOpen
1st
Monitor2nd
Monitor
ON (closed)
Purge
Valve Vent
OK
OK
Malfunction
0.1 kPa
0.5 kPa
DI±260
± DIAGNOSTICSENGINE
454 Author: Date:
2005 SEQUOIA (RM1146U)
(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.

± DIAGNOSTICSENGINE
DI±261
455 Author: Date:
2005 SEQUOIA (RM1146U)
MONITOR STRATEGY
Purge VSV stuck open
Related DTCsP0441Purge VSV stuck closedRelated DTCsP0441
Purge flow
Required sensors/componentsPurge VSV, Pump module
Frequency of operationOnce per driving cycle
DurationPurge VSV stuck open and closed: Within 2 min. (varies with amount of fuel in tank)
Purge flow: Within 30 sec.
MIL operation2 driving cycle
Sequence of operationNone
TYPICAL ENABLING CONDITIONS
ItSpecificationItemMinimumMaximum
The monitor will run whenever these
DTCs are not presentSee 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 pressure525 to 825 mmHg (70 to 110 kPa)
Battery voltage10.5 V±
Vehicle speed±4 km/h (2.5 mph)
Ignition switchOFF
Engine conditionNot running
Time after engine stopped5 hours
FTP sensor malfunction (P0450, P0452,
P0453)Not detected
Purge VSVNot operated by scan tool
Vent valveNot operated by scan tool
Leak detection pumpNot operated by scan tool
Both of the following conditions are met
before IG switch OFFCondition 1 and 2
1. Duration that vehicle is driven5 min.±
2. Purge flowExecuted
ECT4.4 to 35°C (40 to 95°F)
IAT4.4 to 35°C (40 to 95°F)
Example of re±start time±
First time7 hours
Second time9 hours and 30 min.
Key±off monitor sequence1 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
± DIAGNOSTICSENGINE
456 Author: Date:
2005 SEQUOIA (RM1146U) 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 pressureSaturated
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 setCondition 1 and 2
1. Vacuum introduction time±15 min.
2. FTPFTP 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 setCondition 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 pressureSaturated
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 conditionRunning
ECT4.4°C (40°F)±
IAT4.4°C (40°F)±
FTP sensor malfunctionNot detected
Purge VSVNot operated by scan tool
EVAP system checkNot operated by scan tool

± DIAGNOSTICSENGINE
DI±263
457 Author: Date:
2005 SEQUOIA (RM1146U) Battery voltage
10 V±
Purge duty cycle8 %±
TYPICAL MALFUNCTION THRESHOLDS
Detection CriteriaThreshold
Purge VSV stuck open:
FTP when vacuum introduction was compleatHigher than reference pressure x 0.2
Purge VSV stuck closed:
FTP change for 10 sec. after purge VSV ONLess than 2.25 mmHg (0.3 kPa)
Purge flow:
Both of the following conditions are metCondition 1 or 2
1. FTP change when purge operation is startedLess than 0.75 mmHg (0.1 kPa)
2. FTP change during purge operation when vent valve is
closedLess than 3.75 mmHg (0.5 kPa)
MONITOR RESULT (MODE 06 DATA)
Refer to page DI±26 for detailed information on Monitor Result.
INSPECTION PROCEDURE
Refer to the EVAP Inspection Procedure (see page DI±460).

DI±264
± DIAGNOSTICSENGINE
458 Author: Date:
2005 SEQUOIA (RM1146U)
DTC P0450 Evaporative Emission Control System Pres-
sure Sensor/Switch
DTC P0451 Evaporative Emission Control System Pres-
sure Sensor/Switch Range/Performance
DTC P0452 Evaporative Emission Control System Pres-
sure Sensor/Switch Low Input
DTC P0453 Evaporative Emission Control System Pres-
sure Sensor/Switch High Input
DTC SUMMARY
DTCMonitoring ItemsMalfunction Detection ConditionsTrouble AreasDetection Tim-
ingsDetection
Logic
P0450Pressure sensor voltage ab-
normal fluctuationSensor output voltage rapidly fluctuates
beyond upper and lower malfunction
thresholds for 0.5 seconds.
Pump module

Connector/Wire harness
(Pump module ± ECM)

ECM
EVAP monitor-
ing (ignition
OFF)

Ignition ON
1 trip
P0451Pressure sensor noisingSensor output voltage fluctuates fre-
quently in certain time period.

Pump module

Connector/Wire harness
(Pump module ± ECM)

ECM
EVAP monitor-
ing (ignition
OFF)

Engine running
2 trip
P0451Pressure sensor stuckSensor output voltage does vary in cer-
tain time period.

Pump module

Connector/Wire harness
(Pump module ± ECM)

ECM
EVAP monitor-
ing (ignition
OFF)
2 trip
P0452Pressure sensor voltage lowSensor output voltage is less than 0.45
V for 0.5 seconds.

Pump module

Connector/Wire harness
(Pump module ± ECM)

ECM
Ignition ON

EVAP monitor-
ing (ignition
OFF)
1 trip
P0453Pressure sensor voltage highSensor output voltage is more than 4.9
V for 0.5 seconds.

Pump module

Connector/Wire harness
(Pump module ± ECM)

ECM
Ignition ON

EVAP monitor-
ing (ignition
OFF)
1 trip
HINT:
The pressure sensor is built into the pump module.
CIRCUIT DESCRIPTION
The circuit description can be found in the EVAP (Evaporative Emission) Inspection Procedure (see page
DI±460).
DID89±01

B17403
Pressure Sensor Specification:
Output Voltage
Usable Range
4.900 V
4.150 V
1.425 V
0.450 V
Malfunction Area
Pressure
60
kPa11 0
kPa
Malfunction Area
Standard atmospheric pressure is 101.3 kPaHINT:
± DIAGNOSTICSENGINE
DI±265
459 Author: Date:
2005 SEQUOIA (RM1146U)
MONITOR DESCRIPTION
(a) DTC P0450: Pressure sensor voltage abnormal fluctua-
tion.
If the pressure sensor voltage output rapidly fluctuates
between less than 0.45 V and more than 4.9 V, the ECM
interprets this as an open or short circuit malfunction in
the pressure sensor or its circuit, and stops the EVAP
(Evaporative Emission) system monitor. The ECM then il-
luminates the MIL and sets the DTC (1 trip detection log-
ic).
(b) DTC P0451: Pressure sensor noising or stuck
If the pressure sensor voltage output fluctuates rapidly for
10 seconds, the ECM stops the EVAP system monitor.
The ECM interprets this as noise from the pressure sen-
sor, and stops the EVAP system monitor. The ECM then
illuminates the MIL and sets the DTC.
Alternatively, if the sensor voltage output does not
change for 10 seconds, the ECM interprets this as the
sensor being stuck, and stops the monitor. The ECM then
illuminates the MIL and sets the DTC.
(Both the malfunctions are detected by 2 trip detection
logic)
(c) DTC P0452: Pressure sensor voltage low
If the pressure sensor voltage output is below 0.45 V, the
ECM interprets this as an open or short circuit malfunction
in the pressure sensor or its circuit, and stops the EVAP
system monitor. The ECM then illuminates the MIL and
sets the DTC (1 trip detection logic).
(d) DTC P0453: Pressure sensor voltage high
If the pressure sensor voltage output is 4.9 V or more, the
ECM interprets this as an open or short circuit malfunction
in the pressure sensor or its circuit, and stops the EVAP
system monitor. The ECM then illuminates the MIL and
sets the DTC (1 trip detection logic).

DI±266
± DIAGNOSTICSENGINE
460 Author: Date:
2005 SEQUOIA (RM1146U)
MONITOR STRATEGY
P0450Evaporative emission control system pressure
sensor/switch chattering
P0451
Evaporative emission control system pressure
sensor noise
Related DTCs
P0451Evaporative emission control system pressure
sensor stuck
P0452Evaporative emission control system pressure
sensor/switch low input
P0453Evaporative emission control system pressure
sensor/switch high input
Required sensors/componentsPump module
Frequency of operationOnce per driving cycle
Duration0.5 sec.: P0450, P0452, P0453
10 sec.: P0451
MIL operationImmediate: P0450, P0452, P0453
2 driving cycles: P0451
Sequence of operationNone
TYPICAL ENABLING CONDITIONS
ItSpecificationItemMinimumMaximum
The monitor will run whenever these
DTCs are not presentSee page DI±18
Pressure sensor noise:
Atmospheric pressure525 to 825 mmHg (70 to 110 kPa)
Battery voltage10.5 V±
IAT4.4 to 35°C (40 to 95°F)
FTP sensor malfunction (P0450, P0452,
P0453)Not detected
Either of the following conditions is metCondition 1 or 2
1. Time after engine stopped5 hours
2. Engine conditionRunning
Example of re±start time±
First time7 hours
Second time9 hours and 30 min.
Pressure sensor stuck:
Battery voltage10.5 V±
IAT4.4 to 35°C (40 to 95°F)
FTP sensor malfunction (P0450, P0452,
P0453)Not detected
Atmospheric pressure525 to 825 mmHg (70 to 110 kPa)
Time after engine stopped5 hours
Example of re±start time±
First time7 hours
Second time9 hours and 30 min.

± DIAGNOSTICSENGINE
DI±267
461 Author: Date:
2005 SEQUOIA (RM1146U) Pressure sensor chattering, low/high voltage:
Battery voltage8 V±
Ignition switchON
StarterOFF
TYPICAL MALFUNCTION THRESHOLDS
Detection CriteriaThreshold
Pressure sensor noise:
Frequency that FTP change is 0.3 kPa or more10 times or more for 10 sec.
Pressure sensor stuck:
FTP change for 10 sec. during EVAP monitor (0.02 inch
reference pressure)Less than 4.9 mmHg (0.65 kPa)
Pressure sensor chattering:
Pressure sensor voltageLess than 0.45 V, or more than 4.9 V
Pressure sensor low voltage:
Pressure sensor voltageLess than 0.45 V
Pressure sensor high voltage:
Pressure sensor voltageMore than 4.9 V

DI±268
± DIAGNOSTICSENGINE
462 Author: Date:
2005 SEQUOIA (RM1146U)
INSPECTION PROCEDURE
NOTICE:

When a vehicle is brought into the workshop, leave it as it is. Do not change the vehicle condi-
tion. For example, do not tighten the fuel tank cap.

Do not disassemble the pump module.

A hand±held tester is required to conduct the following diagnostic troubleshooting procedure.
1 Confirm DTC and EVAP pressure.
PREPARATION:
(a) Connect a hand±held tester to the DLC3.
(b) Turn the ignition switch to ON (do not start the engine).
(c) Turn the tester ON.
CHECK:
(a) Select the following menu items: DIAGNOSIS / ENHANCED OBD II / DTC INFO / CURRENT CODES.
(b) Read DTCs.
(c) Select the following menu items: DIAGNOSIS / ENHANCED OBD II / DATA LIST / ALL / VAPOR
PRESS.
(d) Read the EVAP (Evaporative Emission) pressure displayed on the tester.
RESULT:
Display (DTC Output)Test ResultsSuspected Trouble AreasProceed To
P0451'
Pressure sensorC
P0452Less than 45 kpa (430 mmHg)

Wire harness/connector (ECM ± pressure
sensor)

Pressure sensor

Short in ECM circuit
A
P0453More than 120 kPa (900 mmHg)

Wire harness/connector (ECM ± pressure
sensor)

Pressure sensor

Open in ECM circuit
B
B Go to step 4.
C Go to EVAP inspection procedure
(See page DI±460).
A