Toyota Sequoia (2005). Manual — part 167
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DIAGNOSTICS
ENGINE
DI–463
657
Components
Operations
Canister
Contains activated charcoal to absorb EVAP (Evaporative Emissions) generated in fuel tank.
Cut–off valve
Located in fuel tank. Valve floats and closes when fuel tank is 100 % full.
Purge VSV (Vacuum
Switching Valve)
Opens or closes line between canister and intake manifold. ECM uses purge VSV to control EVAP purge flow. In order
to discharge EVAP absorbed by canister to intake manifold, ECM opens purge VSV. EVAP discharge volume to intake
manifold controlled by purge VSV duty cycle ratio (current–carrying time). (Open: ON, Close: OFF)
Refueling valve
Controls EVAP pressure from fuel tank to canister. Valve consists of diaphragm, spring and restrictor (diameter: 0.08
inch). When fuel vapor and pressure inside fuel tank increase, valve opens. While EVAP purged, valve closes and re-
strictor prevents large amount of vacuum from affecting pressure in fuel tank. Valve opened while refueling. When valve
open, adding fuel into fuel tank possible.
Roll–over valve
Located in fuel tank. Valve closes by its own weight when vehicle overturns to prevent fuel from spilling out.
Service port
Used for connecting vacuum gauge for inspecting EVAP system.
Soak timer
Built into ECM. To ensure accurate EVAP monitor, measures 5 hours
*
after ignition switch turned to OFF. This allows
fuel to cool down, stabilizing Fuel Tank Pressure (FTP). When approx. 5 hours
*
elapsed, ECM activates.
Pump module
Consists of (a) to (d) below. Pump module cannot be disassembled.
(a) Vent valve
Vents and closes EVAP system. When ECM turns valve ON, EVAP system closed. When, ECM turns valve OFF, EVAP
system vented. Negative pressure (vacuum) created in EVAP system to check for EVAP leaks by closing purge VSV,
turning on vent valve (closed) and operating vacuum pump (refer to fig. 1).
(b) Pressure sensor
Indicates pressure as voltages. ECM supplies regulated 5 V to pressure sensor, and uses feedback from sensor to
monitor EVAP system pressure (refer to fig 2).
(c) Vacuum pump
Creates negative pressure (vacuum) in EVAP system for leak check.
(d) 0.02 inch orifice
Has opening with 0.02 inch diameter. Vacuum produced through orifice by closing purge VSV, turning off vent valve and
operating vacuum pump, to monitor 0.02 inch leak pressure. 0.02 inch leak pressure indicates small leak of EVAP.
HINT:
*:If the engine coolant temperature is not below 35
C after 5 hours after the ignition switch is turned off, the
monitor check starts 2 hours later. If it is still not below 35
C 7 hours after the ignition switch is turned off,
the monitor check starts 2.5 hours later.
A23494
Pump Module (fig. 1):
Condition: Purge Flow
Condition: Leak Check
From Refueling Valve
To Air Filter
(Atmosphere)
Vacuum Pump: OFF
Vent Valve: OFF
(vent)
Pressure Sensor
0.02 Inch Orifice
Canister
: Airflow
Vacuum Pump: ON
Vent Valve: ON
(closed)
A23495
Pressure Sensor Specification (fig. 2)
Output Voltage
Usable Range
4.900 V
4.150 V
1.425 V
0.450 V
Malfunction Area
Pressure
60
kPa
110
kPa
Malfunction Area
Standard atmospheric pressure is 101.3 kPa
HINT:
A23496
Soak Timer Circuit (fig. 3)
Ignition Switch
IGSW
Power
ECM
EFI MAIN
MREL
+B
15 A
Source IC
Soak Timer IC
Main Relay
Control IC
Battery
DI–464
–
DIAGNOSTICS
ENGINE
658
A23565
L5
Pump Module
Pressure Sensor
Vacuum Pump
Vent Valve
Engine Room R/B
Battery
J/C
V4
Purge
VSV
VC
PPMP
E2
MPMP
VPMP
PRG
MREL
EFI Relay
F10
FL Block
5
4
B
B
EFI No.1
2D
1
5
3
EFI No.2
2A
2
4
1
8
9
3
2
G–R
A
A
J/C J2
G–R
G–R
G–R
G–R
IA4
4
J/C J16
B
B
B
J/C
IG4
22
G–R
W–G
E8
34
B–W
E6
8
B–W
IA4
14
2H
6
2
1
2F
1
W–B
J/C J5
A
J48
J49
F
L
G–R
BB1
2
G–R
G–R
BN1
5
P–L
BN1
BN1
BN1
BN1
BN1
P–L
6
BB1
8
P–L
P–L
J49
J48
B
H
E4
5
6
V–G
J48
K
J49
E
V–G
BB1
7
V–G
V–G
4
G–W
3
G–W
BB2
4
G–W
IJ3
3
G–W
IG4
6
G–W
E8
28
22
E4
E4
R–G
IJ3
4
R–G
BB2
2
R–G
2
R–G
G–B
1
G–B
BB2
3
G–B
IJ3
14
G–B
IG4
7
G–B
E8
23
BN1 8
W–B
W–B
BI
ED
ECM
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DIAGNOSTICS
ENGINE
DI–465
659
WIRING DIAGRAM
0.02 inch orifice clogged
Pressure sensor voltage low
P043E
P043F
P0441
P0451
P0452
P0453
P0455
P0456
P2419
P2401
P2402
0.02 inch orifice high–flow
Pressure sensor stuck
Pressure sensor noising
Gross leak
Small leak
Vacuum pump stuck OFF
Vacuum pump stuck ON
Vent valve stuck ON (closed)
Vent valve stuck OFF (vent)
Purge VSV stuck open
Purge VSV stuck closed
Pressure sensor voltage high
DTCs
Malfunctioning Areas
P2420
P0450
DI–466
–
DIAGNOSTICS
ENGINE
660
INSPECTION PROCEDURE
NOTICE:
A hand–held tester is required to conduct the following diagnostic troubleshooting procedure.
HINT:
Using hand–held tester monitor results enables the EVAP (Evaporative Emission) system to be con-
firmed.
Read freeze frame data using a hand–held tester Freeze frame data record the engine condition when
malfunctions are detected. When troubleshooting, freeze frame data can help determine if the vehicle
was moving 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
Confirm DTC.
(a)
Turn the ignition switch to OFF and wait for 10 seconds.
(b)
Turn the ignition switch to ON.
(c)
Turn the ignition switch to OFF and wait for 10 seconds.
(d)
Connect a hand–held tester to the DLC3.
(e)
Turn the ignition switch to ON and turn the tester ON.
(f)
Select the following menu items: DIAGNOSIS / ENHANCED OBD II / DTC INFO / CURRENT CODES.
(g)
Confirm DTCs and freeze frame data.
If any EVAP system DTCs are set, the malfunctioning area can be determined using the table below.
NOTICE:
If the 0.02 inch reference pressure difference between the first and second checks is greater than
the specification, the DTCs corresponding to the reference pressure (P043E, P043F, P0441, P0455,
P0456, P2401, P2420) will be all stored.
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