O2 sensor TOYOTA SEQUOIA 2001 Service Repair Manual

DI±426
± DIAGNOSTICSENGINE
620 Author: Date:
2005 SEQUOIA (RM1146U)
DTC P2444 Secondary Air Injection System Pump Stuck
ON Bank 1
DTC P2445 Secondary Air Injection System Pump Stuck
OFF Bank 1
CIRCUIT DESCRIPTION
Refer to DTC P0412 on page DI±234.
DTC No.DTC Detection ConditionTrouble Area
P2444
Air pump stuck ON.
The secondary air pressure is more than 5 kPa (38 mmHg)
despite the ECM ordering the air pump to turn off.
(2 trip detection logic)
Short in air pump circuit

Air injection driver

Pressure sensor

Open or short in pressure sensor circuit

ECM
P2445
Air pump stuck OFF or air injection volume is insufficient.
The amount of air flow is below the criteria.
(The secondary air pressure is less than specified value de-
spite the ECM ordering the air pump turn ON.)
(2 trip detection logic)

Air pump fuse

Vacuum hose

Air pump assembly

Air injection driver

Open in air pump circuit

Air injection system piping

Pressure sensor

Open or short in pressure sensor circuit

ECM
MONITOR DESCRIPTION
P2444:
The ECM observes the pressure in the secondary air passage using the pressure sensor located on the air
switching valve in the secondary air injection system. The sensor measures the pressure in the secondary
air passage and sends a signal to the ECM.
If the pressure level from the sensor exceed a certain level despite the ECM turning off the air pump, the
ECM interprets this as a fault in the secondary air injection system and sets a DTC.
P2445:
The ECM calculates the amount of air flow in the secondary air system based on the output values of the
pressure sensor and mas air flow meter.
The ECM determines whether the amount of air flow is normal or not according to the calculated value. When
the amount of air flow is below the criteria, the ECM stores the DTC and illuminates the MIL.
DIDMU±01

± DIAGNOSTICSENGINE
DI±427
621 Author: Date:
2005 SEQUOIA (RM1146U)
MONITOR STRATEGY
P2444Air pump is stuck ON
RltdDTCAir pump is stuck OFFRelated DTCsP2445Air flow volume is insufficientP2445
Air pressure sensor is stuck
Required sensors/componentsAIR pump, AIR pressure sensor
Frequency of operationContinuous
Duration
P2444 (Air pump is stuck ON): 20 sec.
P2445 (Air pump is stuck OFF): 8 sec.
P2445 (Air flow volume is insufficient): 8 sec.
P2445 (Air pressure sensor is stuck:) 1.5 sec.
MIL operation2 driving cycles
Sequence of operationNone
TYPICAL ENABLING CONDITIONS
P2444: Air pump is stuck ON
ItSpecificationItemMinimumMaximum
The monitor will run whenever this DTC is
not presentSee page DI±18
Atmospheric pressure570 mmHg (76 kPa)±
Battery voltage11.5 V±
Time after secondary air injection out of
operation10 sec.±
AIR pumpOFF
Air switching valve No. 2 (Bank 1)OFF
Air switching valve No. 2 (Bank 2)OFF
Engine RPM±3,750 rpm
Air injection pressure sensor failNot detected
P2445: Air pump is stuck OFF or air insufficient
ItSpecificationItemMinimumMaximum
The monitor will run whenever this DTC is
not presentSee page DI±18
Atmospheric pressure570 mmHg (76 kPa)±
Battery voltage11.5 V±
Time after secondary air injection out of
operation6 sec.±
AIR pumpON
Air switching valveON
Air switching valve No. 2 (Bank 1)ON
Air switching valve No. 2 (Bank 2)ON
Engine RPM±3,750 rpm
Delay time after engine started6 sec.±
Air injection pressure sensor failNot detected

DI±428
± DIAGNOSTICSENGINE
622 Author: Date:
2005 SEQUOIA (RM1146U)
P2445: Air pressure sensor is stuck
ItSpecificationItemMinimumMaximum
The monitor will run whenever this DTC is
not presentSee page DI±18
ECT at engine start±5°C (41°F)
IAT at engine start±15°C (5°F)±
Time that ECT is 80°C (176°F) or higher10 to 60 min.
Cumulative intake air amount172 g±
One of the following conditions is metCondition 1, 2 or 3
1. Vehicle speed80 km/h (49.7 mile)±
2. Engine RPM0 rpm±
3. Throttle position0 deg
Air switching valveOFF
Air switching valve No. 2 (Bank 1)OFF
Air switching valve No. 2 (Bank 2)OFF
Air injection pressure sensor failNot detected
TYPICAL MALFUNCTION THRESHOLDS
P2444: Air pump is stuck ON
Detection CriteriaThreshold
Smoothed pressure5 kPa (113 mmHg) or more
(when AI OFF (Air pump OFF, all of air switching valves are OFF)
P2445: Air pump is stuck OFF or air insufficient
Detection CriteriaThreshold
Either of the following conditions is metCondition 1 or 2
1. Air flow value100 L/min. or less
2. Smoothed pressureLess than 1 kPa (7.5 mmHg)
(when AI ON (Air pump ON, all of air switching valves are ON)
P2445: Air pressure sensor is stuck
Detection CriteriaThreshold
Detected times of identifying condition 1 is met4 times or more
Air pressure change5 kPa (113 mmHg) or more

B17435Vacuum Hose
DI±432
± DIAGNOSTICSENGINE
626 Author: Date:
2005 SEQUOIA (RM1146U)
3 Check whether DTC output recurs.
PREPARATION:
(a) Start the engine and warm it up.
(b) Turn the ignition switch OFF.
(c) Connect a hand±held tester to the DLC3.
(d) Turn the ignition switch to ON and turn the tester ON.
(e) Clear the DTCs (see page DI±43).
(f) Start the engine.
CHECK:
(a) Perform SYSTEM CHECK to operate the air injection system.
Select the following menu items: DIAGNOSIS/ENHANCED OBD II/SYSTEM CHECK/AIR INJ
CHECK/AUTOMATIC OPERATION
(b) After operating the secondary air injection system, confirm the pending codes for the secondary air
injection system by selecting the following menu items: DIAGNOSIS / ENHANCED OBD II / DTC INFO
/ PENDING CODES.
(c) Read DTCs and check that no DTC is set.
OK:
DTC P2444 or P2445 for the secondary air injection system is not output.
NG Go to step 4.
OK
Check for intermittent problems
(See page DI±11).
4 Check vacuum hose.
CHECK:
(a) Remove the intake manifold (see page EM±36).
(b) Check the vacuum hose connection between the pres-
sure sensor and air switching valve.
OK:
The vacuum hose is securely connected.
CHECK:
(a) Check the vacuum hose for blockage or damage.
OK:
The vacuum hose has no blockage or damage.
NG Repair or replace vacuum hose.
OK

B17434
Pressure GaugePressure Sensor
B17436
± DIAGNOSTICSENGINE
DI±433
627 Author: Date:
2005 SEQUOIA (RM1146U)
5 Inspect ECM (air voltage).
PREPARATION:
(a) Remove the intake manifold (see page EM±36).
(b) Connect the pressure gauge to the pressure sensor as
shown in the illustration.
(c) Connect the hand±held tester to the DLC3 on the vehicle.
(d) Turn the ignition switch ON and push the hand±held tes-
ter main switch ON (Do not start engine).
(e) Select the following items: DIAGNOSIS / ENHANCED
OBD II / DATA LIST / AIR PUMP PRS.
CHECK:
Check that the pressure displayed on the hand±held tester fluc-
tuates when applying the pressure to the pressure sensor with
the pressure gauge.
OK:
Pressure fluctuates in response to the pressure ap-
plied with the pressure gauge.
NG Replace pressure sensor.
OK
6 Check connection of all air injection system piping and hoses.
CHECK:
(a) Remove the intake manifold (see page EM±36).
(b) Check that all the pipes and hoses between the air pump
and air switching valve are securely connected.
OK:
All the air injection pipes and hoses are securely con-
nected.
CHECK:
(a) Check the pipe and hoses for blockage or damage.
OK:
The air injection system pipes and hoses have no
blockage and damage.
NG Repair or replace air injection system piping.
OK

A23475
Pressure GaugePressure Sensor
± DIAGNOSTICSENGINE
DI±439
633 Author: Date:
2005 SEQUOIA (RM1146U)
12 Check air pump operation.
PREPARATION:
(a) Connect the pressure gauge to the air switching valve as
shown in the illustration.
(b) Connect the hand±held tester to the DLC3.
(c) Turn the ignition switch ON and turn the tester ON.
CHECK:
(a) When the air pump is operated using the hand±held tes-
ter, measure the secondary air injection system pressure.
(b) Select the following menu items: DIAGNOSIS/EN-
HANCED OBD II/ACTIVE TEST/AIR INJ CHECK/MANU-
AL OPERATION/OPERATION 3
HINT:
OPERATION 2: AP:ON, EASV:CLOSE, ASV1:CLOSE,
ASV2:CLOSE
NOTICE:
This test only allows technicians to operate the AI system
for 5 seconds. Furthermore, the test can be performed 4
times a trip. If the test is repeated, intervals of at least 30
seconds are required between tests.
While the AI system operation using the hand±held tester
is prohibited, the tester displays the prohibition (WAIT or
ERROR). If the ERROR (AI STATUS NG) is displayed on the
tester, stop the engine for 10 minutes and then try again..
OK:
Standard:
25 to 30 kPa or more
NG Replace air pump.
OK

A23667
Soak Timer Circuit
Ignition Switch
IGSW
Power
ECM
EFI MAIN
MREL+B
15 ASource IC
Soak Timer ICMain Relay
Control IC
Battery DI±442
± DIAGNOSTICSENGINE
636 Author: Date:
2005 SEQUOIA (RM1146U)
DTC P2610 ECM/PCM Internal Engine OFF Timer Perfor-
mance
DTC SUMMARY
DTCMonitoring ItemsMalfunction Detection ConditionsTrouble AreasDetection
TimingsDetection
Logic
P2610Soak timer (built into ECM)ECM internal malfunctionECMEngine
running2 trip
CIRCUIT DESCRIPTION
To ensure the accuracy of the EVAP (Evaporative Emission) monitor values, the soak timer, which is built
into the ECM, measures 5 hours (
15 minutes) from when the ignition switch is turned OFF, before the moni-
tor is run. This allows the fuel to cool down, which stabilizes the Fuel Tank Pressure (FTP). When 5 hours
have elapsed, the ECM turns on.
MONITOR DESCRIPTION
5 hours after the ignition switch is turned OFF, the soak timer activates the ECM to begin the EVAP system
monitor. While the engine is running, the ECM monitors the synchronization of the soak timer and the CPU
clock. If these two are not synchronized, the ECM interprets this as a malfunction, illuminates the MIL and
sets the DTC (2 trip detection logic).
MONITOR STRATEGY
Related DTCsP2610Soak timer (built into ECM)
Required sensors/componentsECM
Frequency of operationOnce per driving cycle
Duration10 min.
MIL operation2 driving cycles
Sequence of operationNone
DIDFX±01

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)
DI±446
± DIAGNOSTICSENGINE
640 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) after 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 then 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.

A23481
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
EVAP Pressure when 0.02 Inch Orifice Clogged:
OK
Malfunction
ON: Open
OFF: Closed
OFF: Vent ON: Closed
10
Standard
sec60
E
± DIAGNOSTICSENGINE
DI±447
641 Author: Date:
2005 SEQUOIA (RM1146U)
(a) P043E: 0.02 inch orifice clogged
In operation B, the vacuum pump creates negative pressure (vacuum) through the 0.02 inch orifice. The
EVAP 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 lower than ±4.85 kPa (±36.38 mmHg)*, the ECM interprets this
as a clog malfunction in the 0.02 inch orifice, and stops the EVAP (Evaporative Emission) system monitor.
The ECM then illuminates the MIL and sets the DTC (2 trip detection logic).
*: The threshold 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.

A23482
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 0.02 Inch Orifice High±flow malfunction: DI±448
± DIAGNOSTICSENGINE
642 Author: Date:
2005 SEQUOIA (RM1146U)
(b) P043F: 0.02 inch orifice high±flow
In operation B, the vacuum pump creates negative pressure (vacuum) through the 0.02 inch orifice. The
EVAP 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)*, the ECM interprets this as
a high±flow malfunction in the 0.02 inch orifice, and stops the EVAP system monitor. The ECM then illumi-
nates the MIL and sets the DTC (2 trip detection logic).
*: The threshold varies according to the atmospheric pressure measured in operation A. The value described
above is based on a atmospheric pressure of 100 kPa (750.1 mmHg): absolute pressure.
MONITOR STRATEGY
RltdDTCP043E0.02 inch orifice clog (built±in pump module)Related DTCsP043F0.02 inch orifice high±flow (built±in pump module)
Required sensors/componentsPump module
Frequency of operationOnce per driving cycle
DurationWithin 2 min. (varies with amount of fuel in tank)
MIL operation2 driving cycle
Sequence of operationNone