Page 465 of 4323
± 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).
Page 466 of 4323

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)
ECMEVAP 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)
ECMEVAP 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)
ECMEVAP 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)
ECMIgnition 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)
ECMIgnition 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
Page 467 of 4323

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).
Page 468 of 4323

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.
Page 469 of 4323
± 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
Page 470 of 4323

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
Page 471 of 4323
B17417
E4
PPMP
± DIAGNOSTICSENGINE
DI±269
463 Author: Date:
2005 SEQUOIA (RM1146U)
2 Measure resistance between terminal PPMP of ECM and body ground.
PREPARATION:
(a) Turn the ignition switch to OFF.
(b) Disconnect the E4 ECM connector.
CHECK:
Measure the resistance between PPMP terminal of the ECM
connector and the body ground.
RESULT:
Test ResultsSuspected Trouble AreasProceed To
10 W or lessWire harness/connector (ECM ± pressure sensor)
Short in pressure sensor circuitA
10 kW or moreWire harness/connector (ECM ± pressure sensor)
Short in ECM circuitB
B Go to step 7.
A
Page 472 of 4323
B17417
E4
PPMP
A23446
L5
DI±270
± DIAGNOSTICSENGINE
464 Author: Date:
2005 SEQUOIA (RM1146U)
3 Measure resistance between terminal PPMP of ECM and body ground.
PREPARATION:
(a) Disconnect the L5 canister connector.
(b) Disconnect the E4 ECM connector.
CHECK:
Check the resistance between PPMP terminal of the ECM con-
nector and the body ground.
Result:
Test ResultsSuspected Trouble AreasProceed To
10 kW or moreShort in pressure sensor circuitA
10 W or lessShort in wire harness/connector (ECM ± pressure sensor)B
A Go to step 5.
B Go to step 6.