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
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
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