TOYOTA LAND CRUISER 1986 Factory Repair Manual

A19639VSV is OFF VSV is ON CCV
Air
E Air
E
FF
E5
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16 Check for open and short in harness and connector between EFI or ECD relay
and EVAP VSV, and EVAP VSV and ECM (See page IN-36).
NG Repair or replace harness or connector.
OK
Replace ECM (See page SF-60).
17 Check CCV.
PREPARATION:
Turn the ignition switch ON.
CHECK:
Check the VSV function.
(1) Connect the terminal CCV of the ECM connector
and body ground (ON).
(2) Disconnect the terminal CCV of the ECM connector
and body ground (OFF).
OK:
(1) VSV is ON:
Air does not flow from port E to port F.
(2) VSV is OFF:
Air from port E flows out through port F.
OK Go to step 20.
NG
18 Check operation of CCV (See page SF-48).
NG Replace CCV.
OK

A19641VSV is ON VSV is OFFTBP
Air
E Air
E
FF
E9
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19 Check for open and short in harness and connector between EFI or ECD relay
and CCV, and CCV and ECM (See page IN-36).
NG Repair or replace harness or connector.
OK
Replace ECM (See page SF-60).
20 Check pressure switching valve.
PREPARATION:
Turn the ignition switch ON.
CHECK:
Check the VSV function.
(1) Connect the terminal TBP of the ECM connector
and body ground (ON).
(2) Disconnect the terminal TBP of the ECM connector
and body ground (OFF).
OK:
(1) VSV is ON:
Air does not flow from port E to port F.
(2) VSV is OFF:
Air from port E flows out through port F.
OK Go to step 23.
NG
21 Check operation of pressure switching valve (See page SF-46).
NG Replace pressure switching valve.
OK

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22 Check for open and short in harness and connector between EFI or ECD relay
and pressure switching valve, and pressure switching valve and ECM (See page
IN-36).
NG Repair or replace harness or connector.
OK
Replace ECM (See page SF-60).
23 Check fuel tank inlet valve.
NG Replace fuel tank inlet valve.
OK
24 Check fuel tank.
NG Replace fuel tank.
OK
It is likely that vehicle user did not properly
close fuel tank cap.

A19378A20057
ECM
EVAP VSV
Charcoal Canister
Fuel Tank Fig. 1
(2)
(3) (4) (6)
(8)
(9) (1)
(5)
(7)Vapor Pressure
Sensor
CCVPressure
Switching
Valve
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DTC P0442 Evaporative Emission Control System Leak
Detected (Small Leak)
DTC P0455 Evaporative Emission Control System Leak
Detected (Gross Leak)
DTC P0456 Evaporative Emission Control System Leak
Detected (Very Small Leak)
CIRCUIT DESCRIPTION
The vapor pressure sensor, canister closed valve (CCV) and pressure switching valve are used to detect
abnormalities in the evaporative emission control system.
The ECM decides whether there is an abnormality in the evaporative emission control system based on the
vapor pressure sensor signal.
DTC P0442, P0455 or P0456 is recorded by the ECM when evaporative emissions leak from the compo-
nents within the dotted line in Fig. 1 below, or when the vapor pressure sensor malfunctions.
DIC2I-01

A21544
CCV
Pressure Switching Valve
EVAP VSV
Cold Start
ECT/IAT near same temp.Open
ClosedOpen ClosedOpen
Closed
Closed
Closed Open
P0441, P0446,
P0455, P2418
Negative Pressure
OccursP0442, P0456
Tank & Canister
Leak CheckP0446
Pressure Switching
Valve Testing
(ex. Fuel tank cap loose)
(ex. Disconnect of vacuum hose)
P2418
CCV
Testing
Pressure
Switching
valve open
malfunction
(P2418)
(P0455) Gross Leak
P0442
P0456
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MONITOR DESCRIPTION
A leak in the evaporative emission system prompts the ECM to set DTC P0442, P0455 or P0456.
The ECM checks for leaks in the system by introducing a high negative pressure (vacuum) from the intake
manifold by commanding the EVAP VSV open while the CCV (vent) is closed and the pressure switching
valve is open. After sufficient time has elapsed the fuel tank should have developed a high negative pressure
(vacuum) and the EVAP VSV closed. The ECM then monitors the pressure-rise (loss of vacuum) in the fuel
tank. If the pressure rises too rapidly, the ECM concludes that there is a leak in the system. The ECM will
turn on the MIL and set a DTC.
The ECM has separate DTCs for small and large leaks:
(1) DTC P0442 is set when the internal fuel tank pressure has a large increase and the EVAP system
has a small leak.
(2) DTC P0455 is set when the EVAP system has various large leaks. Even though the ECM sends
a signal to the EVAP VSV (when CCV is closed) to create a vacuum, the internal fuel tank pres-
sure does not decrease beyond a specified level.
(3) DTC P0456 is set when the internal fuel tank pressure increase slightly and the EVAP system
has a small leak.

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HINT:
Refer to DTCs P0441, P0446 and P2418
DTC No.DTC Detecting ConditionTrouble Area
P0442After the negative pressure introduction has been completed, if
the pressure in the EVAP system sharply increases.
After the negative pressure introduction has been completed, if
the pressure in the EVAP system sharply increases.

Hose or tube cracked, holed, damaged or loose seal ((3) in
Fig. 1)
Fl k i li lld
P0455If the vacuum is not strong enough, the ECM assumes the
EVAP system has a large hole.

Fuel tank cap incorrectly installed

Fuel tank cap cracked or damaged

Vacuum hose cracked, holed, blocked, damaged or discon-
nected ((1), (2), (4), (5), (6), (7), (8) and (9) in Fig. 1)


Fuel tank cracked, holed or damaged
P0456If the pressure in the EVAP system slightly increase while the
ECM performs a leak check.

Fuel tank cracked, holed or damaged

Charcoal canister cracked, holed or damaged

Open or short in vapor pressure sensor circuit

Vapor pressure sensor

ECM
HINT:
Typical DTC output of each trouble part
Trouble partTypical DTC output (*1)
Small LeakP0442 and/or P0456
Medium Leak (ex: Vacuum hose loose)P0455
Large Leak (ex: Fuel tank cap loose)P0441, P0446, P0455 and P2418
EVAP VSVOpen MalfunctionP0441EVAP VSVClose MalfunctionP0441, P0446, P0455 and P2418
CCVOpen MalfunctionP0441, P0446, P0455 and P2418CCVClose MalfunctionP0446
PSithiVlOpen MalfunctionP2418Pressure Switching ValveClose MalfunctionP0441, P0446, P0455 and P2418
*1: ECM may output some other DTC combination.
MONITOR STRATEGY
P0442Small leak (0.040 inch or more large hole) is de-
tected
Related DTCsP0455Gross leak detected
P0456Very small leak (0.020 inch hole) is detected
Main sensors/componentsVapor pressure sensor
Required sensors/componentsRelated sensors/components
Mass air flow sensor, Engine coolant temperature
sensor
EVAP VSV (purge VSV), CCV
Frequency of operationOnce per drive cycle
Duration60 sec.
MIL operation2 drive cycles
Sequence of operationNone

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TYPICAL ENABLING CONDITIONS
ItCriteriaItemMinimumMaximum
The monitor will run whenever the follow-
ing DTCs are not presentSee ºList of disable a monitorº (on page DI-3)
Common pre-conditions for 0.020, 0.040 inch and gross:
Altitude-2,400 m (7,872 ft.)
Throttle position learningCompleted
Vapor pressure sensorNo malfunction
Difference between intake air temperature
and engine coolant temperature at engine
start
-7C (-13F)11.1C (20F)
Vehicle speed conditionA or B
A. Time after vehicle stopped
(Less than 10 km/h (6 mph))90 sec.-
B. Time after vehicle started
(7 km/h (4 mph) or more)20 sec.-
0.020 inch malfunction detection:
Engine coolant temperature at engine
start10C (50F)32C (89.6F)
Intake air temperature at engine start10C (50F)32C (89.6F)
Intake air temperature10°C (50°F)-
Fuel level condition in fuel tank during leak
checkFuel slosh is small (must not drive on road in bad conditions)
Time after engine start-50 min.
Fuel tank pressure condition before leak
check (Fuel tank condition before closed
negative pressure introduction)Tank inside pressure change is small before negative pressure introduction.
(Reference: If fuel in tank is high temperature, vapor volume increase and tank inside pressure
changes also increase)
Vehicle speed and intake air amount
condition before and after negative pres-
sure introduction
Steady speed and not change greatly of intake air amount
Fuel level-90%
0.020 inch leak detectionNot completed
0.040 inch leak detectionNot detected
CCV malfunction, bypass VSV malfunc-
tionNot detected
Vehicle speed-130 km/h (81 mph)
EVAP VSV (Evap purge VSV) malfunctionNot detected
0.040 inch and gross malfunction:
Engine coolant temperature at engine
start10°C (50°F)35°C (95°F)
Intake air temperature at engine start10°C (50°F)35°C (95°F)
Intake air temperature10°C (50°F)-
Fuel level condition in fuel tank during leak
checkFuel slosh is small (must not drive on road in bad conditions)
Time after engine start-50 min.
Fuel tank pressure condition before leak
check (Fuel tank condition before closed
negative pressure introduction)Tank inside pressure change is small before negative pressure introduction.
(Reference: If fuel in tank is high temperature, vapor volume increase and tank inside pressure
changes also increase)

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Vehicle speed and intake air amount
condition before and after negative pres-
sure introduction
Steady speed and not change greatly of intake air amount
Fuel level-90%
0.040 inch leak detectionNot completed
Fuel tank pressure at vacuum introduction
completed-2.4 kPa (-18 mmHg, -0.71 in.Hg)-
P0446 VSV checkNot executed
TYPICAL MALFUNCTION THRESHOLDS
Detection CriteriaThreshold
0.020 inch malfunction detection:
Fuel tank pressure changing value for 5 sec. from -2.0 kPa
(-15 mmHg, -0.59 in.Hg) pointIncrease 0.067 kPa (0.5 mmHg, 0.02 in.Hg) or more
Fuel tank pressure changing value for 5 sec. from -2.7 kPa
(-20 mmHg, -0.79 in.Hg) pointIncrease 0.067 kPa (0.5 mmHg, 0.02 in.Hg) or more
0.040 inch malfunction detection:
Fuel tank pressure changing value for 5 sec. from -2.0 kPa
(-15 mmHg, -0.59 in.Hg) pointIncrease 0.16 kPa (1.2 mmHg, 0.05 in.Hg) or more
Fuel tank pressure changing value for 5 sec. from -2.7 kPa
(-20 mmHg, -0.79 in.Hg) pointIncrease 0.16 kPa (1.2 mmHg, 0.05 in.Hg) or more
Gross leak detection:
Fuel tank pressure min. value at vacuum introduction-2.4 kPa (-18 mmHg, -0.71 in.Hg) or more
MONITOR RESULT
The detailed information is described in CHECKING MONITOR STATUSº (see page DI-3).

TID (Test Identification) is assigned to each emission-related component.

TLT (Test Limit Type):
If TLT is 0, the component is malfunctioning when the test value is higher than the test limit.
If TLT is 1, the component is malfunctioning when the test value is lower than the test limit.

CID (Component Identification) is assigned to each test value.

Unit Conversion is used to calculate the test value indicated on generic OBD scan tools.
TID $02: EVAP - Vacuum Monitor
TLTCIDUnit ConversionDescription of Test ValueDescription of Test Limit
1$01Multiply by 0.0916
(mmHg)Test value of EVAP VSV:
Determined by fuel tank pressure change during vacuum introductionMalfunction criterion
1$02Multiply by 0.0458 and
subtract 2.93 (mmHg)Test value of bypass VSV (pressure switching valve):
Determined by fuel tank pressure change at switching over bypass
VSV
Malfunction criterion
0$03Multiply by 0.0458
(mmHg)Test value of 0.04 inch leak:
Determined by fuel tank pressure changeMalfunction criterion
0$04Multiply by 0.0458
(mmHg)Test value of 0.02 inch leak:
Determined by fuel tank pressure changeMalfunction criterion
1$05Multiply by 0.0458 and
subtract 2.93 (mmHg)Test value of CCV:
Determined by fuel tank pressure change at switching over CCVMalfunction criterion

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WIRING DIAGRAM
Refer to DTC P0441, P0446 and P2418 on page DI-222.
Hand-held tester:
1 Check that fuel tank cap meets OEM specifications.
NG Replace with a cap that meets OEM specifica-
tions.
OK
2 Check that fuel tank cap is correctly installed.
NG Correctly install fuel tank cap.
OK
3 Check fuel tank cap (See page EC-5).
NG Replace fuel tank cap.
OK
4 Check filler neck for damage.
PREPARATION:
Remove the fuel tank cap.
CHECK:
Visually inspect the filler neck for damage.
NG Replace filler pipe.
OK

A19812
VSV is ON
VSV is OFF
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DI-251
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5 Check purge flow.
PREPARATION:
(a) Connect the hand-held tester to the DLC3.
(b) Select the ºENHANCED OBD II / ACTIVE TESTº mode on
the hand-held tester.
(c) Disconnect the vacuum hose for the EVAP VSV from the
charcoal canister.
(d) Start the engine.
(e) Select the item ºEVAP (ALON) / ALLº in the ACTIVE TEST
and operate EVAP VSV.
CHECK:
When the EVAP VSV is operated by the hand-held tester,
check whether the disconnected hose applies suction to your
finger.
OK:
VSV is ON:
Disconnected hose applies suction to your finger.
VSV is OFF:
Disconnected hose applies no suction to your finger.
OK Go to step 9.
NG
6 Check vacuum hose between intake manifold and EVAP VSV, and EVAP VSV and
charcoal canister.
CHECK:
(a) Check that the vacuum hose is connected correctly.
(b) Check the vacuum hose for looseness and disconnection.
(c) Check the vacuum hose for cracks, hole, damage and blockage.
NG Repair or replace vacuum hose.
OK