sensor TOYOTA CAMRY 2000 Service Repair Manual

EVAP SYSTEM OPERATION INFORMATION ± EG005-01 April 27, 2001
Page 2 of 14
Early Type (Non±Intrusive) EVAP System Overview
There are a variety of EVAP systems in use with different monitoring strategies. It is
essential that the EVAP system be correctly identified before beginning diagnosis. The
Repair Manual is the best source for this information. The following information covers
the different systems.
The first system described is the Early Type (Non±Intrusive) EVAP System. Refer to the
Applicable Vehicles chart for applicability information.
Onboard Recovery Valve
(Fill Check Valve)Vapor
Pressure
SensorVapor
Pressure
Sensor
Three Way
VSVVacuum
Check
ValveTank Valve
AssemblyPressure
ValveCanister
To
Manifold
Vacuum
Purge
Valve
Filtered
Air
Air Drain Valve
Air Valve AssemblyAir Inlet ValveAir Inlet LineService
Port
Purge Operation
When the engine has reached
predetermined parameters (closed loop,
engine temp. above 125
F, etc.), stored
fuel vapors are purged from the canister
whenever the purge VSV is opened by
the ECM. At the appropriate time, the
ECM will turn on the purge VSV.
The ECM will change the duty ratio cycle
of the purge VSV thus controlling purge
flow volume. Purge flow volume is
determined by manifold pressure and the
duty ratio cycle of the purge VSV.
Atmospheric pressure is allowed into the
canister to ensure that purge flow is
constantly maintained whenever purge
vacuum is applied to the canister (see
Figure 1).
Early Type
System
Description
Figure 1. Purge OperationFresh Air Inlet
Purge VSV

EVAP SYSTEM OPERATION INFORMATION ± EG005-01 April 27, 2001
Page 3 of 14
ORVR Operation
During refueling, low pressure above the
diaphragm in the onboard recovery valve
lifts allowing fuel vapors into the charcoal
canister. At the same time, the air drain
valve opens and the charcoal absorbs the
fuel vapors (see Figure 2).
Early Type (Non±Intrusive) EVAP System DTCs
EVAP Monitor Leak Operation P0440
The ECM tests for leaks by measuring
EVAP system pressure in the lines,
charcoal canister, and fuel tank. When
the EVAP pressure is higher or lower than
atmospheric pressure, the ECM
concludes that no leaks are present.
EVAP pressure is measured by the vapor
pressure sensor. If either the tank or
canister purge side is at atmospheric
pressure under specific conditions, the
ECM determines there is a leak.
If DTC P0440 is present, the leak is on
the fuel tank side of the EVAP system.
This also includes the lines between the
fuel tank and part of the canister. When
the Vapor Pressure sensor is measuring
tank pressure, the ECM is observing
changes in pressure and comparing tank
pressure to atmospheric pressure. No
difference in pressure indicates a leak.
The ECM may take 20 minutes or more to
complete testing the fuel tank side (see
Figure 3).
Canister Leak Detection P0446
When the ECM switches the vapor
pressure VSV to canister side, the ECM
measures canister pressure. A leak on
the canister side can set multiple DTCs
(see Figure 4).Early Type
System
Description
(Continued)
Figure 2. ORVR Operation
Figure 3. Fuel Tank Side of System
Figure 4. Canister Side of System

EVAP SYSTEM OPERATION INFORMATION ± EG005-01 April 27, 2001
Page 4 of 14
Vapor Purge Flow P0441
The EVAP monitor is designed to detect:
Restricted vapor purge flow when the
purge VSV is open
Inappropriate vapor purge flow when
the purge VSV is closed
Under normal purge conditions, pressure
pulsations generated by the cycling of the
purge VSV are present in the canister
and detected by the Vapor Pressure
sensor.
Three±Way VSV P0446
The three±way VSV is connected to the Vapor Pressure sensor, canister, and fuel tank.
This VSV allows the Vapor Pressure sensor to detect either canister or tank pressure.
There are two modes the ECM can use to determine if the three±way VSV is
malfunctioning. The three±way VSV is judged to be normal if there is pressure difference
between the tank and canister when the three±way VSV is switched to look at the
charcoal canister and fuel tank side of system.
If there isn't any pressure difference between the fuel tank and canister, the ECM looks
for the following conditions:
During purging, pressure pulsations generated by the purge VSV are not present in
the canister as detected by Vapor Pressure sensor, the three±way VSV is judged to
be defective.
If there are pressure pulsations detected by the Vapor Pressure sensor present in the
fuel tank, the three±way VSV is judged to be defective.
Late Type (Intrusive) EVAP System Overview
The Late Type EVAP System, also known as the Intrusive type, was developed to meet
the very stringent, mandated standard of detecting a hole 0.020 inch (0.5 mm). This
system uses many of the same components as the early type EVAP system. Purge,
vacuum relief, pressure relief, and ORVR operations are identical to the early type. Refer
to the Applicable Vehicles chart for applicability information.
The following changes were made to the Late Type EVAP System:
Vapor pressure sensor connected to the fuel tank.
Bypass VSV in the place of the three way VSV.
Canister Closed Valve (CCV) on the air inlet line.Early Type
System
Description
(Continued)
Figure 5. Flow During Purge Operation
Late Type
System
Description

EVAP SYSTEM OPERATION INFORMATION ± EG005-01 April 27, 2001
Page 5 of 14
Late Type (Intrusive EVAP System) (Except ECHO)
Onboard Recovery Valve
(Fill Check Valve)Vapor
Pressure
SensorVacuum
Check
ValveTank Valve
AssemblyTank
Pressure
Valve
Canister
To
Manifold
Vacuum
Purge
VSV
Filtered
Air
Air Drain Valve
Air Valve AssemblyAir Inlet ValveCanister
Closed Valve
Bypass
VSVAir
Inlet LineService
Port
Tank Side
The bypass VSV and the fill check valve
assembly isolates the tank pressure side
from the canister side (see Figure 1).
Canister Side
The bypass VSV and the Fill Check valve
also isolate the canister side from the
tank side (see Figure 2).
Late Type
System
Description
(Continued)
Except ECHO
Figure 1. Fuel Tank Side of System
Except ECHO
Figure 2. Canister Side of System

EVAP SYSTEM OPERATION INFORMATION ± EG005-01 April 27, 2001
Page 6 of 14
ECHO Late Type (Intrusive EVAP System)
The ECHO uses a Late Type EVAP System but is configured with some small
differences. For the ECHO, the Canister Closed Valve is located directly on the canister.
Additionally, the bypass VSV has been eliminated.
Onboard Recovery
Valve (Fill Check Valve)Vapor
Pressure
Sensor
Air Inlet ValveCanister
Canister Closed ValveAir Valve AssemblyAir Drain Valve Assembly
To
Manifold
Vacuum
Purge
Valve
Filtered
Air
Late Type (Intrusive) EVAP System Monitor Sequence
The monitoring sequence for leak detection is different from that of the Early Type EVAP
System. The Late Type applies a very small vacuum to the EVAP system. The ECM then
determines if there is a problem in the system based on the vapor pressure sensor
signal.
Monitor Sequence (Except ECHO)
CCV Open
Purge ClosedOpenClosed
Purge ClosedOpenOpen
Cold Start ECT/IAT
Near Same TempNegative
Pressure
(Vacuum)
OccursLeak Testing
Period OccursCCV
Op Open
Time in Minutes Bypass Closed
Closed
Bypass
VSV Op Vapor
Pressure
Sensor
Signal
P0441P0440
P0442P0446
Late Type
System
Description
(Continued)
Late Type
System
Monitor
Sequence

EVAP SYSTEM OPERATION INFORMATION ± EG005-01 April 27, 2001
Page 7 of 14
ECHO Monitor Sequence
CCV Open
Purge
ClosedOpenClosed
Purge ClosedOpen Open
Cold Start ECT/IAT
Near Same TempNegative
Pressure
(Vacuum)
OccursTank &
Canister
Leak CheckCCV
Testing Vapor
Pressure
Sensor
Signal
Monitor Operation
The monitor sequence begins with a cold
engine start. The IAT and ECT sensors
must have approximately the same
temperature reading.
The ECM is constantly monitoring fuel
tank pressure. As the temperature of the
fuel increases, pressure slowly rises.
The ECM will purge the charcoal canister
at the appropriate time (see Figure 1).
With bypass VSV closed, pressure will
continue to rise in fuel tank.
Late Type
System
Monitor
Sequence
(Continued)
Except ECHO
Figure 1. Canister Purge
ECHO
Figure 1. Canister Purge

EVAP SYSTEM OPERATION INFORMATION ± EG005-01 April 27, 2001
Page 10 of 14
This diagnostic process tests the EVAP System. The following diagnostic tips may be
used in conjunction with the Diagnostic Procedures for EVAP DTCs listed in the Repair
Manual. They may be used for all Late Type (Intrusive) EVAP Systems and for all EVAP
DTCs. Refer to the Applicable Vehicles chart for applicability information.
The EVAP System Pressure Test Kit (P/N 00002±6872A) and the Scan Tool can be used
to diagnose the EVAP System. Measuring EVAP System pressures using the EVAP
System Pressure Tester Gauge and the Scan Tool can aid in the identification of leaks in
the system.
System Outline (Except ECHO)
Onboard Recovery Valve
(Fill Check Valve)Vapor
Pressure
SensorVacuum
Check
ValveTank Valve
AssemblyTank
Pressure
Valve
Canister
To
Manifold
Vacuum
Purge
VSV
Filtered
Air
Air Drain Valve
Air Valve AssemblyAir Inlet ValveCanister
Closed Valve
Bypass
VSVAir
Inlet LineService
Port
ECHO System Outline
Onboard Recovery Valve
(Fill Check Valve)
To
Manifold
Vacuum
Filtered
AirPurge
VSV
Air Drain
Valve
Air Valve
Assembly
Canister
Closed
Valve
Canister
Vapor
Pressure
Sensor
Air Inlet Valve
Air
Inlet LineService
Port
Diagnostic
Tips for Late
Type EVAP
System

EVAP SYSTEM OPERATION INFORMATION ± EG005-01 April 27, 2001
Page 11 of 14
Diagnostic Process Flow Chart
(Continued on following page)
PRELIMINARY CHECK
Fuel level should be between
1/4 and 3/4
Visually inspect for presence
of Fuel/Gas Cap
DO NOT TIGHTEN OR REMOVE!
PRESSURIZE EVAP SYSTEM (System Integrity Check)
This test checks for leaks in the canister and fuel tank sides. The CCV and Air Inlet Lines will be checked
separately.
A) Clamp the air drain hose on the charcoal canister with the supplied hose pliers from the EVAP System
Pressure Test Kit.
B) Locate the vapor pressure sensor. If the vapor pressure sensor has two hoses connected to it,
disconnect the hose between the air drain hose fitting at the vapor pressure sensor and plug the hose.
C) Connect the pressure supply hose from the Pressure Test Kit to the Green EVAP System Service Port
located on the EVAP Purge VSV line in the engine compartment.
D) Using the directions on the inside of the EVAP System Pressure Test Kit lid, pressurize the EVAP
system. Once pressurized, turn off the pump and seal the system (Pressure Hold Switch to ªClosedº
and Vent Switch to ªClosed).
E) After 30 seconds, note the pump pressure gauge reading and the Scan Tool vapor pressure
sensor reading.
F) Compare the readings to one of the four conditions listed below and proceed as directed.
DO NOT PROCEED! NG
OK
SCAN TOOL SETUP
A) Connect Scan Tool to DLC3 on vehicle.
B) Go to the SETUP menu and select UNIT CONVERSION.
C) Under VAPOR PRESSURE, Select ABS for absolute pressure, and mmHg for millimeters of mercury.
This is to match the Repair Manual specifications.
D) Go back to FUNCTION SELECT menu and select ENHANCED OBD II.
E) Select NORMAL MODE. Then select CURRENT DATA and USER SELECT.
F) Using the arrow key, select VAPOR PRESS from the DATA LIST and select YES.
G) Press ENTER. You will now be able to monitor the Vapor Pressure Sensor reading.
START
If vehicle is ECHO, go directly to ªECHO Canister and Tank Leak Checkº on page 14.
If vehicle is not ECHO, follow the flow chart below.
Diagnostic
Tips for Late
Type EVAP
System
(Continued)

Toyota Supports ASE CertificationPage 1 of 5
EG013-02Title:
M.I.L. ON" P0440, P0441 & P0446
Models:
'98 ± '99 Camry & Solara
Technical Service
BULLETIN
July 12, 2002

Under certain driving conditions, some 1998 ± 1999 model year Camry and Solara
vehicles may exhibit a M.I.L. ªONº with DTCs P0440, P0441 and P0446 stored due to an
inoperative Vapor Pressure Sensor 3 way Vacuum Switching Valve (VSV). An improved
Vapor Pressure Sensor VSV has been developed to correct this condition.

1998 ± 1999 model year Camry & Solara vehicles.
PREVIOUS PART NUMBERCURRENT PART NUMBERPART NAMEQTY
90910±1210990910±12271Vapor Pressure Sensor VSV1
TOOLS & MATERIALPART NUMBERQUANTITY
Toyota Diagnostic Tester Kit*
010012711
12 Megabyte Diagnostic Tester Program Card
with version 9.01a Software (or later)*
01002593-0051
Hand Operated Vacuum PumpN/A1
Digital Volt Ohm Meter (DVOM)09082±00050
(Or Equivalent)1
* Essential SSTs.
NOTE:
Additional Diagnostic Tester Kits, Program Cards or SSTs may be ordered by calling
OTC at 1-800-933-8335.
OP CODEDESCRIPTIONTIMEOFPT1T2
178011
R & R Vacuum Switching Valve (4 Cylinder)0.4
90910 121097283178011R & R Vacuum Switching Valve (6 Cylinder)0.290910±121097283
Applicable Warranty*:
This repair is covered under the Toyota Comprehensive Warranty. This warranty is in
effect for 36 months or 36,000 miles, whichever occurs first, from the vehicle's
in-service date.
* Warranty application is limited to correction of a problem based upon a customer's specific complaint.
ENGINE
Introduction
Applicable
Vehicles
Parts
Information
Required Tools
& Material
Warranty
Information

M.I.L. ªONº P0440, P0441 & P0446 ± EG013-02July 12, 2002
Page 2 of 5
Test VSV Operation Using ACTIVE TEST on the Toyota Diagnostic Tester
1. Test operation of the Vapor Pressure Sensor VSV using the Toyota Diagnostic Tester
in ACTIVE TEST (see screen flow in Figure 1).
INJECTOR 0.0ms
IGN ADVANCE 5.0deg
CALC LOAD 0%
MAF 0gm/s
ENGINE SPD 0rpm
COOLANT TEMP 77.0F
INTAKE AIR 87.8F
THROTTLE POS 16%
CTP SW ON
VEHICLE SPD 0MPH
02S B1 S1 0.00V
2: CUSTOMIZE
3: ECU REPROGRAMFUNCTION SELECT FOR
NORTH AMERICA
B
*APPLICATION SELECT*
A
1: DIAGNOSISDIAGNOSTIC MENU
ENGINE
C
PRESS INJ VOL
A/F CONTROL
FUEL PMP SP CTL
A/C CUT SIG
CAN CTRL VSV
EVAP VSV (ALONE)
FUEL PUMP/SPD
LINE PRESS UPSELECT DATA
E
SELECT DATA
D
TANK BYPASS VSVUSER DATA
[ENTER]
F
G
TANK BYPASS VSV OFF
1: OBD/MOBD
3: CARB OBD II
4: BREAK±OUT BOX
5: NVH
6: AUTOPROBE
7: 02 RPM CHECK
8: SNAPSHOT REVIEW
9: SETUP
0: GAS ANALYSIS2: ENHANCED OBD1: DATA LIST
2: DTC INFO
4: SNAPSHOT
5: SYSTEM CHECK
6: RESET MEMORY
7: MONITOR STATUS
8: CHECK MODE
3: ACTIVE TEST
ALL
INJECTOR 0.0ms
IGN ADVANCE 5.0deg
CALC LOAD 0%
MAF 0gm/s
ENGINE SPD 0rpm
COOLANT TEMP 77.0F
INTAKE AIR 87.8F
THROTTLE POS 16%
CTP SW ON
VEHICLE SPD 0MPH
02S B1 S1 0.00V Figure 1: Testing Operation of Vapor Pressure Sensor VSV using ACTIVE TEST
TANK BYPASS VSV ON
NOTE:
Vapor Pressure Sensor VSV is listed as TANK BYPASS VSV on the Diagnostic Tester. Inspection &
Repair
Procedure