Page 609 of 4323

B17396
HT +B
AF± AF+ Sensor 1A/F Sensor Component Side:
Front View
A19288
± DIAGNOSTICSENGINE
DI±407
601 Author: Date:
2005 SEQUOIA (RM1146U)
HINT:
Read freeze frame data using a hand±held tester. Freeze frame data record the engine condition when mal-
functions are detected. When troubleshooting, freeze frame data can help determine if the vehicle was mov-
ing or stationary, if the engine was warmed up or not, if the air±fuel ratio was lean or rich, and other data,
from the time the malfunction occurred.
1 Check resistance of air±fuel ratio (A/F) sensor heater.
PREPARATION:
Disconnect the air±fuel ratio (A/F) sensor connector.
CHECK:
Measure resistance between the terminals of the A/F sensor
connector.
OK:
Tester ConnectionSpecified Condition
HT (1) ± +B (2)Between 1.8 W and 3.4 W at 20C (68F)
HT (1) ± AF± (4)10 kW or higher
NG Replace air±fuel ratio (A/F) sensor.
OK
2 Check A/F relay.
PREPARATION:
Remove the A/F relay from the engine room J/B.
CHECK:
Inspect the A/F relay.
OK:
Terminal No.ConditionSpecified Condition
1 ± 2ConstantContinuity
UsuallyNo Continuity
3 ± 5Apply B+ between
terminals 1 and 2Continuity
NG Replace EFI relay.
OK
Page 610 of 4323

A23659
Wire Harness Side:
HT
A38
Sensor 1A/F Sensor Connector
AF+
Front ViewAF±
+B A39
B17415A55007
E7ECM Connector
HA1A
A1A+
A1A±
A2A+
A2A±HA2A
A23512
Reference (Bank 1 Sensor 1 System Drawing):
A/F Sensor A/F Relay
Heater
Sensor
A1A+ HA1A
Duty
Control ECM
From
Battery
A/F Heater
Fuse
A1A±
To EFI Relay DI±408
± DIAGNOSTICSENGINE
602 Author: Date:
2005 SEQUOIA (RM1146U)
3 Check for open and short in harness and connector between ECM and A/F sen-
sor.
PREPARATION:
(a) Disconnect the A38 or A39 A/F sensor connector.
(b) Turn the ignition switch to ON.
CHECK:
(a) Measure the voltage between the +B terminal of the A/F
sensor connector and body ground.
OK:
Standard:
Tester ConnectionsSpecified Conditions
+B (2) ± Body groundBetween 9 V and 14 V
PREPARATION:
(a) Turn the ignition switch to OFF.
(b) Disconnect the E7 ECM connector.
CHECK:
(a) Check the resistance.
OK:
Standard (Check for open):
Tester ConnectionsSpecified Conditions
HT (A38±1) ± HA1A (E7±2)
HT (A39±1) ± HA2A (E7±1)Below 1 W
AF+ (A38±3) ± A1A+ (E7±22)
AF+ (A39±3) ± A2A+ (E7±23)Below 1 W
AF± (A38±4) ± A1A± (E7±30)
AF± (A39±4) ± A2A± (E7±31)Below 1 W
Standard (Check for short):
Tester ConnectionsSpecified Conditions
HT (A38±1) or HA1A (E7±2) ± Body ground
HT (A39±1) or HA2A (E7±1) ± Body ground10 kW or higher
AF+ (A38±3) or A1A+ (E7±22) ± Body ground
AF+ (A39±3) or A2A+ (E7±23) ± Body ground10 kW or higher
AF± (A38±4) or A1A± (E7±30) ± Body ground
AF± (A39±4) or A2A± (E7±31) ± Body ground10 kW or higher
Page 611 of 4323
± DIAGNOSTICSENGINE
DI±409
603 Author: Date:
2005 SEQUOIA (RM1146U)
NG Replace or replace harness or connector.
OK
Replace ECM (See page SF±80).
Page 612 of 4323

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
Page 613 of 4323

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: 0.02 Inch Leak Pressure Measurement
Negative
Pressure Atmospheric
Pressure
Operation C: EVAP Leak Check
Air Filter
Purge VSV: OFFOFF (vent)
ON
OFF
OFF
ON
ON (closed)ON
ON
ON (closed)
± DIAGNOSTICSENGINE
DI±411
605 Author: Date:
2005 SEQUOIA (RM1146U)
MONITOR DESCRIPTION
5 hours* after the ignition switch is turned OFF, the electric vacuum pump creates negative pressure (vacu-
um) in the EVAP (Evaporative Emission) system. The ECM monitors for leaks and actuator malfunctions
based on the EVAP pressure.
HINT:
*: If the engine coolant temperature is not below 35C (95F) 5 hours after the ignition switch is turned off,
the monitor check starts 2 hours later. If it is still not below 35C (95F) 7 hours after the ignition switch is
turned off, the monitor check starts 2.5 hours later.
SequenceOperationsDescriptionsDuration
±ECM activationActivated by soak timer, 5 hours (7 or 9.5 hours) after ignition switch turned to OFF.±
AAtmospheric pressure
measurement
Vent valve turned OFF (vent) and EVAP system pressure measured by ECM in order to
register atmospheric pressure.
If EVAP pressure is not between 70 kPa and 110 kPa (525 mmHg and 825 mmHg), ECM
cancels EVAP system monitor.
10 seconds
B
First 0.02 inch leak
pressure measure-
mentIn order to determine 0.02 inch leak pressure standard, vacuum pump creates negative pres-
sure (vacuum) through 0.02 inch orifice and them ECM checks if vacuum pump and vent
valve operate normally.
60 seconds
CEVAP system pres-
sure measurement
Vent valve turned ON (closed) to shut EVAP system.
Negative pressure (vacuum) created in EVAP system, and EVAP system pressure then
measured.
Write down the measured value as it will be used in the leak check.
If EVAP pressure does not stabilize within 15 minutes, ECM cancels EVAP system monitor.
15 minutes*
DPurge VSV monitorPurge VSV opened and then EVAP system pressure measured by ECM.
Large increase indicates normal.10 seconds
E
Second 0.02 inch leak
pressure measure-
mentLeak check is performed after second 0.02 inch leak pressure standard is measured.
If stabilized system pressure higher than second 0.02 inch leak pressure standard, ECM
determines that EVAP system leaking.
60 seconds
FFinal checkAtmospheric pressure measured and then monitoring result recorded by ECM.±
* If only a small amount of fuel is in the fuel tank, it takes longer for the EVAP pressure to stabilize.
Page 614 of 4323

A23664
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
sec
EVAP Pressure when Vacuum Pump Stuck OFF: DI±412
± DIAGNOSTICSENGINE
606 Author: Date:
2005 SEQUOIA (RM1146U)
(a) P2401: Vacuum pump stuck OFF
In operation B, the vacuum pump creates negative pressure (a vacuum) through the 0.02 inch orifice. The
EVAP (Evaporative Emission) system pressure is then measured by the ECM, using the pressure sensor,
to determine the 0.02 inch leak pressure standard. If the pressure is higher than ±1.06 kPa (±7.95 mmHg)*,
or lower than ±4.85 kPa (±36.38 mmHg)*, the ECM interprets this as the vacuum pump being stuck OFF
(not operating). The ECM illuminates the MIL and sets the DTC (2 trip detection logic).
*: The thresholds vary according to the atmospheric pressure measured in operation A. The values de-
scribed above are based on an atmospheric pressure of 100 kPa (750.1 mmHg): absolute pressure.
Page 615 of 4323

A23663
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: VentON: Closed
10
Standard
sec60
E
sec
EVAP Pressure when Vacuum Pump Stuck ON:
± DIAGNOSTICSENGINE
DI±413
607 Author: Date:
2005 SEQUOIA (RM1146U)
(b) P2402: Vacuum pump stuck ON
In operation B, the vacuum pump creates negative pressure (a vacuum) through the 0.02 inch orifice. The
EVAP (Evaporative Emission) system pressure is then measured by the ECM, using the pressure sensor,
to determine the 0.02 inch leak pressure standard. If the pressure is higher than ±1.06 kPa (±7.95 mmHg)*,
or lower than ±4.85 kPa (±36.38 mmHg)*, the ECM interprets this as the vacuum pump being stuck ON (re-
maining ON all the time). The ECM illuminates the MIL and sets the DTC (2 trip detection logic).
*: The thresholds vary according to the atmospheric pressure measured in operation A. The values de-
scribed above are based on an atmospheric pressure of 100 kPa (750.1 mmHg): absolute pressure.
HINT:
The detection logic of DTCs P2401 and P2402 is the same because in both cases the 0.02 inch leak pressure
standard measured in operation B is compared to the atmospheric pressure registered in operation A. The
ECM calculates the difference between these pressures by deducting [the 0.02 inch leak pressure standard]
from [the stored atmospheric pressure], and uses this to monitor the EVAP system pressure change.
MONITOR STRATEGY
RltdDTCP2401Vacuum pump stuck OFFRelated DTCsP2402Vacuum pump stuck ON
Required sensors/componentsPump module
Frequency of operationOnce per driving cycles
DurationWithin 2 min.
MIL operation2 driving cycles
Sequence of operationNone
Page 616 of 4323

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)±