TOYOTA AVALON 2001 Service Repair Manual

A02042
ON
FC
- DIAGNOSTICSENGINE
DI-155
311 Author
: Date
:
2001 AVALON (RM808U)
OK
6 Check for open in harness and connector between circuit opening relay (Mark-
ing: C/OPN) and fuel pump, and fuel pump and body ground
(See page IN-30).
NG Repair or replace harness or connector.
OK
Check and replace ECM (See page IN-30).
OBD II scan tool (excluding TOYOTA hand-held tester):
1 Check operation of fuel pump.
PREPARATION:
(a) Remove the glove compartment (See page SF-82).
(b) Turn the ignition switch ON.
CHECK:
(a) Connect between terminal FC of the ECM connector and
body ground.
(b) Check that the pulsation damper screw rises up when
connecting between terminal FC of the ECM connector
and body ground.
OK:
The pulsation damper screw rises up.
OK Check for starter signal circuit
(See page DI-142).
NG
2 Check for ECM power source circuit (See page DI-148).

A02064
ON
FC
(+) (-)
DI-156
- DIAGNOSTICSENGINE
312 Author
: Date
:
2001 AVALON (RM808U)
NG Repair or replace.
OK
3 Check circuit opening relay (Marking: C/OPN) (See page SF-63).
NG Replace circuit opening relay.
OK
4 Check voltage between terminal FC of ECM connector and body ground.
PREPARATION:
(a) Remove the glove compartment (See page SF-83).
(b) Turn the ignition switch ON.
CHECK:
Measure the voltage between terminal FC of the ECM connec-
tor and body ground.
OK:
Voltage: 9 - 14 V
OK Go to step 5.
NG
Check for open in harness and connector between EFI main relay (Marking: EFI) and circuit open-
ing relay (Marking: C/OPN), and circuit opening relay and ECM (See page IN-30).
5 Check fuel pump (See page SF-6).
NG Repair or replace fuel pump.
OK

- DIAGNOSTICSENGINE
DI-157
313 Author
: Date
:
2001 AVALON (RM808U)
6 Check for open in harness and connector between circuit opening relay (Mark-
ing: C/OPN) and fuel pump, and fuel pump and body ground
(See page IN-30).
NG Repair or replace harness or connector.
OK
Check and replace ECM (See page IN-30).

A06092
1
3
5
24
6 IACV No.2IACV No.1, No.2 closed (VSV: OFF)
Throttle Valve30°
3,700 rpm
Engine Speed
Throttle Valve
Opening Angle
FI7011 FI6570
IACV No.1
2,700 rpmIACV No.1 open (VSV: ON)
IACV No.2 closed (VSV: OFF)
IACV No.1, No.2 open (VSV: ON)
A11667
From BatteryEngine Room J/B
2B 2G
2F
2B
2
4
1 EFI
No.1EFI Relay
W-B
B-W 9
E01ACISE4 R-Y
2 VSV for ACIS No.1
ED17
L-O B
4 EFI
No.21
2
From
Terminal
MREL of
ECME01
ACI1E5 15
B-W B-WECM
VSV for ACIS No.2W-R 1 2
53
- DIAGNOSTICSENGINE
DI-145
301 Author
: Date
:
2001 AVALON (RM808U)
IACV Control Circuit
CIRCUIT DESCRIPTION
This circuit opens and closes the IACV (Intake Air Control Valve) in response to the engine load in order to
increase the intake efficiency (ACIS: Acoustic Control Induction System).
When the engine speed is 3,700 rpm or less and the throttle valve opening angle is 30° or more, the ECM
turns the two VSV ON or OFF and operate the IACV.
WIRING DIAGRAM
DI08E-09

A00307
ON
VSV is ON VSV is OFF
Air Filter Air
Air
E
FE
F
BE6653
FI7073 FI7074
DI-146
- DIAGNOSTICSENGINE
302 Author
: Date
:
2001 AVALON (RM808U)
INSPECTION PROCEDURE
TOYOTA hand-held tester:
1 Connect TOYOTA hand-held tester, and check operation of VSV for ACIS.
PREPARATION:
(a) Remove the fuse cover on the instrument panel.
(b) Connect the TOYOTA hand-held tester to the DLC3.
(c) Turn the ignition switch ON and TOYOTA hand-held tes-
ter main switch ON.
(d) Select the INTAKE CTRL VSV from the ACTIVE TEST
menu on the TOYOTA hand-held tester.
CHECK:
Check the operation of the VSV when the VSV is operated by
the TOYOTA hand-held tester.
OK:
VSV is ON:
Air from port E flows out through port F.
VSV is OFF:
Air from port E flows out through the air filter.
OK Check vacuum tank (See page SF-46).
NG
2 Check VSV for ACIS (See page SF-68).
NG Replace VSV for ACIS.
OK
3 Check for open and short in harness and connector between EFI main relay
(Marking: EFI) and ECM (See page IN-30).
NG Repair or replace harness or connector.
OK

A11824
ON
ACIS
(+)
(-)ACI1
- DIAGNOSTICSENGINE
DI-147
303 Author
: Date
:
2001 AVALON (RM808U)
Check and replace ECM (See page IN-30).
OBD II scan tool (excluding TOYOTA hand-held tester):
1 Check VSV for ACIS (See page SF-68).
NG Replace VSV for ACIS.
OK
2 Check voltage between terminals ACIS, ACI1 of ECM connector and body
ground.
PREPARATION:
(a) Remove the glove compartment (See page SF-82).
(b) Turn the ignition switch ON.
CHECK:
Measure the voltage between terminals ACIS, ACI1 of the ECM
connector and body ground.
OK:
Voltage: 9 - 14 V
NG Check for open and short in harness and con-
nector between EFI main relay (Marking: EFI)
and ECM (See page IN-30).
OK
3 Check vacuum tank (See page SF-58).
NG Repair or replace.
OK
Check and replace ECM (See page IN-30).

DI07F-09
A06106
B+
Thermister
Power Transister
Platinum Hot Wire
B
Output
Voltage A
FI6929
S05741
- DIAGNOSTICSENGINE
DI-23
179 Author
: Date
:
2001 AVALON (RM808U)
CIRCUIT INSPECTION
DTC P0100 Mass Air Flow Circuit Malfunction
CIRCUIT DESCRIPTION
The mass air flow meter uses a platinum hot wire. The hot wire air flow meter consists of a platinum hot wire,
thermistor and a control circuit installed in a plastic housing. The hot wire air flow meter works on the principle
that the hot wire and thermistor located in the intake air bypass of the housing detect any changes in the
intake air temperature.
The hot wire is maintained at the set temperature by controlling the current flow through the hot wire. This
current flow is then measured as the output voltage of the air flow meter.
The circuit is constructed so that the platinum hot wire and thermistor provide a bridge circuit with the power
transistor controlled so that the potential of A and B remains equal to maintain the set temperature.
DTC No.DTC Detecting ConditionTrouble Area
P0100Open or short in mass air flow meter circuit with more than 3
sec. engine speed 4,000 rpm or less
Open or short in mass air flow meter circuit

Mass air flow meter

ECM
If the ECM detects DTC P0100 it operates the fail-safe function, keeping the ignition timing and injection
volume constantly and making it possible to drive the vehicle.
HINT:
After confirming DTC P0100, use the OBD II scan tool or TOYOTA hand-held tester to confirm the mass
air flow ratio from the CURRENT DATA.
Mass Air Flow Value (gm/sec.)Malfunction
0.0
Mass air flow meter power source circuit open

VG circuit open or short
271.0 or more
E2G circuit open

A11668
Engine Room J/B
EFI No.1
2G
2B 2A
2F2
5
1 3
2B-W
4L-O
4 2
EFI No.2 EFI Relay
From BatteryB
Mass Air
Flow Meter3
2 1
EDW-B
R-BECM
E2GVG
E2 R10
19
E5E5
From
Terminal
MREL of
ECM
DI-24
- DIAGNOSTICSENGINE
180 Author
: Date
:
2001 AVALON (RM808U)
WIRING DIAGRAM
INSPECTION PROCEDURE
HINT:
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.
1 Connect OBD II scan tool or TOYOTA hand-held tester, and read value of mass
air flow rate.
PREPARATION:
(a) Connect the OBD II scan tool or TOYOTA hand-held tester to the DLC3.
(b) Turn the ignition switch ON and push the OBD II scan tool or TOYOTA hand-held tester main switch
ON.
(c) Start the engine.
CHECK:
Read the mass air flow rate on the OBD II scan tool or TOYOTA hand-held tester.
RESULT:
Type IType II
Mass Air Flow Rate (gm/sec.)0.0271.0 or more
Type I Go to step 2.
Type II Go to step 5.

A00436
ON
4
BE6653
S05337
(+)
(-)
A02017
VG
(+)
(-)
- DIAGNOSTICSENGINE
DI-25
181 Author
: Date
:
2001 AVALON (RM808U)
2 Check voltage of mass air flow meter power source.
PREPARATION:
(a) Disconnect the mass air flow meter connector.
(b) Turn the ignition switch ON.
CHECK:
Measure the voltage between terminal 4 of the mass air flow
meter connector and body ground.
OK:
Voltage: 9 - 14 V
NG Check for open in harness and connector be-
tween EFI main relay (Marking: EFI) and mass
air flow meter (See page IN-30).
OK
3 Check voltage between terminal VG of ECM connector and body ground.
PREPARATION:
(a) Remove the glove compartment (See page SF-82).
(b) Start the engine.
CHECK:
Measure the voltage between terminal VG of the ECM connec-
tor and body ground while the engine is idling.
OK:
Voltage:
1.1 - 1.5 V (P or N position and A/C switch OFF)
OK Check and replace ECM (See page IN-30).
NG
4 Check for open and short in harness and connector between mass air flow meter
and ECM (See page IN-30).
NG Repair or replace harness or connector.
OK

A02018
E2G
DI-26
- DIAGNOSTICSENGINE
182 Author
: Date
:
2001 AVALON (RM808U)
Replace mass air flow meter.
5 Check continuity between terminal E2G of ECM connector and body ground.
PREPARATION:
Remove the glove compartment (See page SF-82).
CHECK:
Check the continuity between terminal E2G of the ECM con-
nector and body ground.
OK:
Continuity (1 W or less)
NG Check and replace ECM (See page IN-30).
OK
6 Check for open in harness and connector between mass air flow meter and ECM
(See page IN-30).
NG Repair or replace harness or connector.
OK
Replace mass air flow meter.