2001 TOYOTA AVALON check engine

BE6653
A10278A10604A10952
VSV is ONVSV is OFF ON
TBP
OFFON
Air
E Air
E
FF
- DIAGNOSTICSENGINE
DI-95
251 Author
: Date
:
2001 AVALON (RM808U)
18 Check for open and short in harness and connector between EFI main relay
(Marking: EFI) and VSV for CCV, and VSV for CCV and ECM (See page IN-30).
NG Repair or replace harness or connector.
OK
Check and replace ECM (See page IN-30).
19 Check VSV for pressure switching valve.
PREPARATION:
(a) Remove the grove compartment (See page SF-82).
(b) Turn the ignition switch ON.
CHECK:
Check the VSV function.
(1) Connect between terminal TBP of the ECM connec-
tor and body ground (ON).
(2) Disconnect between terminal TBP of the ECM con-
nector and body ground (OFF).
OK:
(1) VSV is ON:
Air from port E flows out through port F.
(2) VSV is OFF:
Air does not from flow port E to port F.
OK Go to step 22.
NG
20 Check operation of VSV for pressure switching valve (See page SF-72).
OK Go to step 21.

DI-96
- DIAGNOSTICSENGINE
252 Author
: Date
:
2001 AVALON (RM808U)
NG
Replace VSV and charcoal canister, and then clean vacuum hoses between charcoal canister
and VSV for pressure switching valve, and VSV for pressure switching valve and fuel tank.
21 Check for open and short in harness and connector between EFI main relay
(Marking: EFI) and VSV for pressure switching valve, and VSV for pressure
switching valve and ECM (See page IN-30).
NG Repair or replace harness or connector.
OK
Check and replace ECM (See page IN-30).
22 Check the fuel tank over fill check valve (See page EC-6).
NG Replace fuel tank over fill check valve or fuel
tank.
OK
Check and replace charcoal canister (See
page IN-30).

A10145
ECM
Fuel Tank Charcoal Canister VSV for
EVAPFuel Tank Over
Fill Check Valve
Vapor Pressure Sensor
VSV for
CCVVSV for
Pressure
Switching Valve
- DIAGNOSTICSENGINE
DI-97
253 Author
: Date
:
2001 AVALON (RM808U)
DTC P0450 Evaporative Emission Control System Pres-
sure Sensor Malfunction
DTC P0451 Evaporative Emission Control System Pres-
sure Sensor Range/Performance
CIRCUIT DESCRIPTION
The vapor pressure sensor, VSV for canister closed valve (CCV) and VSV for 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 P0450 or P0451 is recorded by the ECM when the vapor pressure sensor malfunction.
DTC No.DTC Detecting ConditionTrouble Area
P0450
10 seconds or less after engine starting condition vapor pres-
sure sensor fixed value continues for fixed value or more: (2
trip detection logic)
P0451
Vapor pressure sensor output extremely changes under condi-
tions of (a) and (b): (2 trip detection logic)
(a) Vehicle speed: 0 km/h (0mph), Engine speed: Idling and
VSV for pressure switching valve is OFF
(b) vavor pressure sensor value
opening pressure valve of
charcoal canister
Open or short in vapor pressure sensor circuit

Vapor pressure sensor

ECM
DI081-04

DI-98
- DIAGNOSTICSENGINE
254 Author
: Date
:
2001 AVALON (RM808U)
WIRING DIAGRAM
Refer to DTC P0440 or P0442 on page DI-74.
INSPECTION PROCEDURE
HINT:

If DTC P0441, P0446, P0450 or P0451 is output after DTC P0440 or P0442, first trouble shoot DTC
P0441, P0446 P0450 or P0451. If no malfunction is detected, troubleshoot DTC P0440 or P0442 next.

Read freeze frame data using TOYOTA hand-held tester or OBD II scan tool. Because freeze frame
records the engine conditions when the malfunction is detected. When troubleshooting, it is useful for
determining whether the vehicle was running or stopped, the engine was warmed up or not, the air-fuel
ratio was lean or rich, etc. at the time of the malfunction.

When the ENGINE RUN TIME in the freeze frame data is less than 200 seconds, carefully check the
VSV for EVAP, charcoal canister and vapor pressure sensor.
1 Check voltage between terminals VC and E2 of ECM connector (See page
DI-74, step 9).
NG Check and replace ECM (See page IN-30).
OK
2 Check voltage between terminals PTNK and E2 of ECM connectors (See page
DI-74, step 10).
OK Check and replace ECM (See page IN-30).
NG
3 Check for open and short in harness and connector between vapor pressure sen-
sor
and ECM (See page IN-30).
NG Repair or replace harness or connector.
OK
Replace vapor pressure sensor.

A02030
E7 Connector
SPD
A02029
E7 ConnectorON
SPD(-) (+)
DI-100
- DIAGNOSTICSENGINE
256 Author
: Date
:
2001 AVALON (RM808U)
1 Check operation of speedometer.
CHECK:
Drive the vehicle and check if the operation of the speedometer in the combination meter is normal.
HINT:
The vehicle speed sensor is operating normally if the speedometer display is normal.
NG Check speedometer circuit (See page BE-43).
OK
2 Check for short in harness and connector between terminal SPD of ECM and
body ground.
PREPARATION:
(a) Remove the glove compartment (See page SF-83).
(b) Disconnect the E7 connector from the ECM.
CHECK:
Check the continuity between terminal SPD of the ECM con-
nector and body ground.
OK:
No continuity (1 MW or higher)
NG Repair or replace harness or connector.
OK
3 Check voltage between terminal SPD of ECM connector and body ground.
PREPARATION:
(a) Remove the glove compartment (See page SF-83).
(b) Disconnect the E7 connector from the ECM.
(c) Turn the ignition switch ON.
CHECK:
Measure the voltage between terminal SPD of the ECM con-
nector and body ground.
OK:
Voltage: 9 - 14 V
NG Check for open in harness and connector be-
tween J/B No.3 and ECM (See page IN-30).

- DIAGNOSTICSENGINE
DI-101
257 Author
: Date
:
2001 AVALON (RM808U)
OK
4 Check for open in harness and connector between J/B No.3 and combination
meter (See page IN-30).
NG Repair or replace harness or connector.
OK
Check and replace ECM (See page IN-30).

A07628
ON
RSOE4 Connector
(+) (-)
- DIAGNOSTICSENGINE
DI-103
259 Author
: Date
:
2001 AVALON (RM808U)
1 Check idle speed.
When using TOYOTA hand-held tester:
PREPARATION:
(a) Warm up the engine to normal operating temperature.
(b) Switch off all the accessories.
(c) Switch off the A/C.
(d) Shift transmission into the N range or neutral position.
(e) Connect the TOYOTA hand-held tester to the DLC3 on the vehicle and select the ACTIVE TEST
mode.
CHECK:
Check the difference of the engine speed between the ones, less than 5 sec. and more than 5 sec. after
switching the TE1 from OFF to ON by the TOYOTA hand-held tester.
OK:
Difference of engine speed: More than 100 rpm
When not using TOYOTA hand-held tester:
PREPARATION:
(a) Warm up the engine to normal operating temperature.
(b) Switch off all the accessories.
(c) Switch off the A/C.
(d) Shift transmission into the N range or neutral position.
(e) Connect the OBDII scan tool to DLC3 on the vehicle.
(f) Using SST, connect terminals TE1 and E1 of the DLC1.
SST 09843-18020
CHECK:
Check the difference of engine speed between the ones, less than 5 sec. and more than 5 sec. after connect-
ing terminals TE1 and E1 of the DLC1.
OK:
Difference of engine speed: More than 100 rpm
OK Go to step 6.
NG
2 Check voltage between terminal RSO of ECM connector and body ground.
PREPARATION:
(a) Remove the glove compartment (See page SF-83).
(b) Disconnect the E4 connector from the ECM.
(c) Turn the ignition switch ON.
CHECK:
Measure the voltage between terminal RSO of the ECM con-
nector and body ground.
OK:
Voltage: 9 - 14 V

DI-104
- DIAGNOSTICSENGINE
260 Author
: Date
:
2001 AVALON (RM808U)
OK Go to step 4.
NG
3 Check IAC valve (See page SF-43).
NG Replace IAC valve.
OK
Check for open and short in harness and connector between engine room J/B and IAC valve, and
IAC valve and ECM (See page IN-30).
4 Check operation of IAC valve (See page SF-46).
NG Repair or replace IAC valve.
OK
5 Check blockage of IAC valve and passage to bypass throttle valve.
NG Repair or replace IAC valve.
OK
Check and replace ECM (See page IN-30).
6 Check for A/C signal circuit (See page DI-824).
NG Repair or replace.