2001 TOYOTA SEQUOIA Page 18

± DIAGNOSTICSENGINE
DI±405
599 Author: Date:
2005 SEQUOIA (RM1146U) Time after A/F sensor heating
20 sec.±
Battery voltage10.5 V±
Ignition switchON
Others:
Battery voltage10.5 V±
Ignition switchON
TYPICAL MALFUNCTION THRESHOLDS
Detection CriteriaThreshold
P2238, P2241 (A/F sensor open circuit between AF+ and AF±):
A/F sensor admittanceBellow 0.022 1/ohm
P2238, P2241 (A/F sensor short circuit between AF+ and GND):
A/F+ terminal voltage0.5 V or less
P2238, P2241 (A/F sensor short circuit between AF+ and AF±):
Difference between A/F+ terminal and AF± terminal voltage0.1 V or less
P2239, P2242 (A/F sensor short circuit between AF+ and +B):
A/F+ terminal voltageMore than 4.5 V
P2252, P2255 (A/F sensor short circuit between AF± and GND):
A/F± terminal voltage0.5 V or less
P2253, P225+ (A/F sensor short circuit between AF± and +B):
A/F± terminal voltageMore than 4.5 V
WIRING DIAGRAM
Refer to DTC P2195 on page DI±383.
INSPECTION PROCEDURE
HINT:
Hand±held tester only:
Malfunctioning areas can be identified by performing the A/F CONTROL function provided in the ACTIVE
TEST. The A/F CONTROL function can help to determine whether the Air±Fuel Ratio (A/F) sensor, Heated
Oxygen (HO2) sensor and other potential trouble areas are malfunctioning.
The following instructions describe how to conduct the A/F CONTROL operation using a hand±held tester.
(1) Connect a hand±held tester to the DLC3.
(2) Start the engine and turn the tester ON.
(3) Warm up the engine at an engine speed of 2,500 rpm for approximately 90 seconds.
(4) On the tester, select the following menu items: DIAGNOSIS / ENHANCED OBD II / ACTIVE
TEST / A/F CONTROL.
(5) Perform the A/F CONTROL operation with the engine in an idling condition (press the RIGHT
or LEFT button to change the fuel injection volume).
(6) Monitor the voltage outputs of the A/F and HO2 sensors (AFS B1S1 (AFS B2S1) and OS2 B1S2
(O2S B2S2)) displayed on the tester.
HINT:

The A/F CONTROL operation lowers the fuel injection volume by 12.5 % or increases the injection
volume by 25 %.

Each sensor reacts in accordance with increases and decreases in the fuel injection volume.

± DIAGNOSTICSENGINE
DI±409
603 Author: Date:
2005 SEQUOIA (RM1146U)
NG Replace or replace harness or connector.
OK
Replace ECM (See page SF±80).

DI±410
± DIAGNOSTICSENGINE
604 Author: Date:
2005 SEQUOIA (RM1146U)
DTC P2401 Evaporative Emission System Leak Detec-
tion Pump Control Circuit Low
DTC P2402 Evaporative Emission System Leak Detec-
tion Pump Control Circuit High
DTC SUMMARY
DTCsMonitoring ItemsMalfunction Detection ConditionsTrouble AreasDetection
TimingsDetection
Logic
P2401Vacuum pump stuck OFF
Vacuum pump creates negative pressure
through 0.02 inch orifice, and EVAP system
pressure measured to determine leak pres-
sure standard. 0.02 inch leak pressure
standard is measured at the start and at the
end of the leak check.
If system pressure higher than ±1.06 kPa
(±7.93 mmHg)*, or lower than ±4.85 kPa
(±36.38 mmHg)*, ECM determines that
vacuum pump stuck OFF.

Pump module

Connector/Wire harness
(Pump module ± ECM)

ECMWhile
ignition
switch
OFF
2 trip
P2402Vacuum pump stuck ON
Vacuum pump creates negative pressure
through 0.02 inch orifice, and EVAP system
pressure measured to determine leak pres-
sure standard.
If system pressure higher than ±1.06 kPa
(±7.93 mmHg)*, or lower than ±4.85 kPa
(±36.38 mmHg)*, ECM determines that
vacuum pump stuck ON.

Pump module

Connector/Wire harness
(Pump module ± ECM)

ECMWhile
ignition
switch
OFF
2 trip
*: The threshold values vary according to the atmospheric pressure measured in operation A. The values
described in the table above are based on an atmospheric pressure of 100 kPa (750.1 mmHg).
HINT:
The vacuum pump 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).
DIDFV±01

DI±414
± DIAGNOSTICSENGINE
608 Author: Date:
2005 SEQUOIA (RM1146U)
TYPICAL ENABLING CONDITIONS
ItSpecificationItemMinimumMaximum
The monitor will run whenever these
DTCs are not presentSee page DI±18
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±
Next sequence is run if all of following
conditions setCondition 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 ±1.057 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)±

± DIAGNOSTICSENGINE
DI±415
609 Author: Date:
2005 SEQUOIA (RM1146U) 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 ±1.057 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)
TYPICAL MALFUNCTION THRESHOLDS
Detection CriteriaThreshold
Following values are when atmospheric pressure is 760
mmHg (100 kPa)±
One of the following conditions setCondition 1, 2, 3, 4 or 5
1. FTP when 4 sec. after reference pressure measurement
began±7.5 mmHg (±1 kPa) or more
2. Reference pressure±36.38 mmHg (±4.85 kPa) or less
3. Reference pressure±7.93 mmHg (±1.057 kPa) or more
4. Reference pressureNot saturated
5. Reference pressure difference between first and secondMore than 5.25 mmHg (0.7 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±416
± DIAGNOSTICSENGINE
610 Author: Date:
2005 SEQUOIA (RM1146U)
DTC P2419 Evaporate Emission System Switching
Valve Control Circuit Low
DTC P2420 Evaporate Emission System Switching
Valve Control Circuit High
DTC SUMMARY
DTCsMonitoring ItemsMalfunction Detection ConditionsTrouble AreasDetection
TimingsDetection
Logic
P2419Vent valve stuck closed
Vacuum pump creates negative pressure
through 0.02 inch orifice and EVAP system
pressure measured to determine leak pres-
sure standard.
If system pressure higher than ±1.06 kPa
(±7.95 mmHg)* 4 seconds after vacuum
pump turned ON, ECM determines that
vent valve stuck closed.

Pump module

Connector/Wire harness
(Pump module ± ECM)

ECMWhile
ignition
switch
OFF
2 trip
P2420Vent valve stuck open (vent)
Vacuum pump creates negative pressure
through 0.02 inch orifice and EVAP system
pressure measured to determine leak pres-
sure standard. 0.02 inch leak pressure
standard is measured at the start and at the
end of the leak check.
If system pressure does not increase by
more than 0.3 kPa (2.25 mmHg) within 10
seconds when vent valve turned ON, ECM
determines that vent valve stuck close.

Pump module

Connector/Wire harness
(Pump module ± ECM)

ECMWhile
ignition
switch
OFF
2 trip
*: The threshold value varies according to the atmospheric pressure measured in operation A. The value
described above is based on an atmospheric pressure of 100 kPa (750.1 mmHg): absolute pressure.
HINT:
The vent valve 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).
DIDFW±01

A23666
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
EVAP Pressure when Vent Valve Stuck OFF (vent):
OK
Malfunction
ON: Open
OFF: Closed
OFF: Vent ON: Closed
10
Standard
sec60
E
± DIAGNOSTICSENGINE
DI±419
613 Author: Date:
2005 SEQUOIA (RM1146U)
(b) P2420: Vent valve stuck open (vent)
In operation C, the vent valve turns ON (closes) and the EVAP (Evaporative Emission) system pressure is
then measured by the ECM, using the pressure sensor, to conduct an EVAP leak check. If the pressure does
not increase when the vent valve is open, the ECM interprets this as the vent valve being stuck open. The
ECM illuminates the MIL and sets the DTC.
MONITOR STRATEGY
RltdDTCP2419Vent valve stuck openRelated DTCsP2420Vent valve stuck closed
Required sensors/componentsVent valve
Frequency of operationOnce per driving cycle
Duration8 sec. (P2419), 10 sec. (P2420)
MIL operation2 driving cycles
Sequence of operationNone
TYPICAL ENABLING CONDITIONS
ItSpecificationItemMinimumMaximum
The monitor will run whenever these
DTCs are not presentSee page DI±18
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

± DIAGNOSTICSENGINE
DI±421
615 Author: Date:
2005 SEQUOIA (RM1146U) 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)
TYPICAL MALFUNCTION THRESHOLDS
Detection CriteriaThreshold
Vent valve stuck open:
Following valuers are when atmospheric pressure is 760
mmHg (100 kPa)±
One of the following conditions setCondition 1, 2, 3, 4 or 5
1. FTP when 4 sec. after reference pressure measurement
began±7.5 mmHg (±1 kPa) or more
2. Reference pressure±36.38 mmHg (±4.85 kPa) or less
3. Reference pressure±7.93 mmHg (±1.057 kPa) or more
4. Reference pressureNot saturated
5. Reference pressure difference between first and secondMore than 5.25 mmHg (0.7 kPa)
Vent valve stuck closed:
FTP change for 10 sec. after vent valve openedLess than 2.25 mmHg (0.3 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).