2001 TOYOTA AVALON check engine

- DIAGNOSTICSENGINE
DI-79
235 Author
: Date
:
2001 AVALON (RM808U)
11 Check for open and short in harness and connector between vapor pressure
sensor and ECM (See page IN-30).
NG Repair or replace harness or connector.
OK
Replace vapor pressure sensor.
12 Check fuel tank and fuel tank over fill check valve for cracks and damage.
NG Replace fuel tank or fuel tank over fill check
valve.
OK
It is likely that vehicle user did not properly close fuel tank cap. Please explain to customer how
to properly install fuel tank cap.

A10142
ECM
Fuel Tank Charcoal Canister VSV for
EVAP
(1) Fig. 1
(2)
(3) (4)
(5)(6)
(7)
Fuel Tank Over
Fill Check Valve
(10)
(9)
Vapor Pressure
Sensor
VSV for
CCVVSV for
Pressure
Switching Valve
(8)
(11) DI-80
- DIAGNOSTICSENGINE
236 Author
: Date
:
2001 AVALON (RM808U)
DTC P0441 Evaporative Emission Control System Incor-
rect Purge Flow
DTC P0446 Evaporative Emission Control System Vent
Control Malfunction
CIRCUIT DESCRIPTION
The vapor pressure sensor, VSV for canister closed valve (CCV), 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.
DTCs P0441 and P0446 are recorded by the ECM when evaporative emissions leak from the components
within the dotted line in Fig. 1 below, or when there is a malfunction in either the VSV for EVAP, the VSV for
pressure switching valve, or in the vapor pressure sensor itself.
DI6T7-01

- DIAGNOSTICSENGINE
DI-81
237 Author
: Date
:
2001 AVALON (RM808U)DTC No.
DTC Detecting ConditionTrouble Area
P0441
Pressure in charcoal canister and fuel tank does not drop dur-
ing purge control (2 trip detection logic)
Vacuum hose cracks, holed blocked, damaged or discon-
nected ((1), (2), (3), (4), (5), (6), (7), (8), (9), (10) and (11) in
Fig 1)P0441
During purge cut-off, negative pressure incomming in the char-
coal canister and fuel tank will not stop. (2 trip detection logic)
Fig. 1)

Fuel tank cap incorrectly installed

Fuel tank cap cracked or damaged

Open or short in vaporpressure sensorcircuit
When VSV for pressure switching valve is ON, ECM judges
that there is no continuity between vapor pressure sensor, fuel
tank and charcoal canister (2 trip detection logic)

Open or short in vapor pressure sensor circuit

Vapor pressure sensor

Open or short in VSV circuit for EVAP

VSV for EVAP
O h t i VSV i it f CCV
P0446
When VSV for pressure switching valve is turned OFF, pres-
sure in fuel tank is maintained at atmospheric pressure (2 trip
detection logic)

Open or short in VSV circuit for CCV

VSV for CCV

Open or short in VSV circuit for pressure switching valve

VSV for pressure switching valve
When VSV for CCV is ON, pressure in charcoal canister and
fuel tank is maintained at atmospheric pressure (2 trip detec-
tion logic)
g

Fuel tank cracked, holed or damaged

Charcoal canister cracked, holed or damaged

Fuel tank over fill check valve cracked damaged

ECM
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 troubleshoot 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
vapor pressure sensor.
TOYOTA hand-held tester:
1 Check whether hose close to fuel tank have been modified, and check whether
there are signs of any accident near fuel tank or charcoal canister (See page
DI-74, step 1).
NG Repair or replace.
OK
2 Check that fuel tank cap is TOYOTA genuine parts (See page DI-74, step 2).
NG Replace to TOYOTA genuine parts.

DI-82
- DIAGNOSTICSENGINE
238 Author
: Date
:
2001 AVALON (RM808U)
OK
3 Check that fuel tank cap is correctly installed (See page DI-74, step 3).
NG Correctly install fuel tank cap.
OK
4 Check fuel tank cap (See page EC-6, step 4).
NG Replace fuel tank cap.
OK
5 Check filler neck for damage (See page DI-74, step 5).
NG Replace filler pipe.
OK
6 Check vacuum hoses between vapor pressure sensor and fuel tank, charcoal
canister and VSV for pressure switching valve, and VSV for pressure switching
valve and charcoal canister (See page DI-74, step 6).
NG Repair or connect VSV or sensor connector.
OK
7 Check hose and tube between fuel tank and charcoal canister (See page
DI-74, step 7).

- DIAGNOSTICSENGINE
DI-83
239 Author
: Date
:
2001 AVALON (RM808U)
NG Repair or replace.
OK
8 Check VSV connector for EVAP, VSV connector for CCV, VSV connector for pres-
sure switching valve and vapor pressure sensor connector for looseness and
disconnection.
NG Repair or connect VSV or sensor connector.
OK
9 Check vacuum hoses ((8), (9), (10) and (11) in Fig. 1 in circuit description).
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.
OK
10 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
11 Check voltage between terminals PTNK and E2 of ECM connectors (See page
DI-74, step 10).
OK Go to step 13.

A00230
VSV is ON
VSV is OFF
DI-84
- DIAGNOSTICSENGINE
240 Author
: Date
:
2001 AVALON (RM808U)
NG
12 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.
13 Check purge flow.
PREPARATION:
(a) Connect the TOYOTA hand-held tester to the DLC3.
(b) Select the ACTIVE TEST mode on the TOYOTA hand-
held tester.
(c) Disconnect the vacuum hose for the VSV for the EVAP
from the charcoal canister.
(d) Start the engine.
CHECK:
When the VSV for the EVAP is operated by the TOYOTA hand-
held tester, check whether the disconnected hose applies suc-
tion 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 17.
NG
14 Check vacuum hose between intake manifold and VSV for EVAP, and VSV for
EVAP and charcoal canister.
CHECK:
(a) Check that the vacuum hose is connected correctly.

A10150A10149BE6653
A10281VSV is ONVSV is OFF ON
Air
FAir
E
F E
- DIAGNOSTICSENGINE
DI-85
241 Author
: Date
:
2001 AVALON (RM808U)
(b) Check the vacuum hose for looseness and disconnection.
(c) Check the vacuum hose for cracks, hole, damage and blockage.
NG Repair or replace.
OK
15 Check operation of VSV for EVAP (See page SF-65).
OK Go to step 16.
NG
Replace VSV and charcoal canister, and then clean vacuum hoses between throttle body and
VSV for EVAP, and VSV for EVAP and charcoal canister.
16 Check for open and short in harness and connector between EFI main relay
(Marking: EFI) and VSV for EVAP, and VSV for EVAP and ECM (See page
IN-30).
NG Repair or replace harness or connector.
OK
Check and replace ECM (See page IN-30).
17 Check VSV for CCV.
PREPARATION:
(a) Connect the TOYOTA hand-held tester to the DLC3.
(b) Disconnect the vacuum hose for the VSV for the CCV
from the charcoal canister.
(c) Turn the ignition switch ON and push the TOYOTA hand-
held tester main switch ON.
(d) Select the ACTIVE TEST mode on the TOYOTA hand-
held tester.

DI-86
- DIAGNOSTICSENGINE
242 Author
: Date
:
2001 AVALON (RM808U)
CHECK:
Check the VSV operation when it is operated by the TOYOTA
hand-held tester.
OK:
VSV is ON:
Air does not flow from port E to port F.
VSV is OFF:
Air from port E flows out through port F.
OK Go to step 21.
NG
18 Check vacuum hose between VSV for CCV 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.
OK
19 Check operation of VSV for CCV (See page SF-70).
OK Go to step 20.
NG
Replace VSV and charcoal canister, and then
clean vacuum hose between charcoal canis-
ter and VSV for CCV.
20 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.