2001 TOYOTA AVALON diagram

A11425
EFI No.1
FL
MainIG Switch
AM2
BatteryEFI Relay
C/OPN Relay
Fuel Pump
ST
RelayStarter Park/ Neutral
Position SwitchECM
FC
Tr
STA
NE (STA Signal)
(NE Signal) MAINMREL
IGSW
ST DI-152
- DIAGNOSTICSENGINE
308 Author
: Date
:
2001 AVALON (RM808U)
Fuel Pump Control Circuit
CIRCUIT DESCRIPTION
In the diagram below, when the engine is cranked, current flows from terminal ST of the ignition switch to
the starter relay (Marking: ST) coil and also current flows to terminal STA of ECM (STA signal).
When the STA signal and NE signal are input to the ECM, Tr is turned ON, current flows to coil of the circuit
opening relay (Marking: C/OPN), the relay switches on, power is supplied to the fuel pump and the fuel pump
operates.
While the NE signal is generated (engine running), the ECM keeps Tr ON (circuit opening relay ON) and the
fuel pump also keeps operating.
DI6TE-01

A11672
From
Terminal
MREL of
ECM From
Battery1 5
2 B-R3
C/OPN Relay Driver Side R/B No.6
6
66 6 B-R 1
IF1 W-R
W-B
2C
2F13
EFI
No.1 AM2
EFI Relay 5
1B
EDEngine Room J/B
43
22B
1 2G
46 7
2C 2
BK 7 4
IF1ECM
E01
ID2E8
Fuel
Pump
AL-B
W-BJ11
J/CFC
G-B3
5 41
L-B B-O IG SwitchW-B
W-R
L-O
BE6653A02330
A02405
ON
- DIAGNOSTICSENGINE
DI-153
309 Author
: Date
:
2001 AVALON (RM808U)
WIRING DIAGRAM
INSPECTION PROCEDURE
TOYOTA hand-held tester:
1 Connect TOYOTA hand-held tester, and check operation of fuel pump.
PREPARATION:1
(a) Connect the TOYOTA hand-held tester to the DLC3.
(b) Turn the ignition switch ON and push the TOYOTA hand-
held tester main switch ON.
(c) Use the ACTIVE TEST mode to operate the fuel pump.
CHECK:
Check that the pulsation damper screw rises up when the fuel
pump is operated by the TOYOTA hand-held tester.
OK:
The pulsation damper screw rises up.
OK Check for starter signal circuit
(See page DI-142).
NG

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

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.

A00310A09772
5 V
THA
E2
E1 22
18 4
5R Intake Air Temp. Sensor
(Built into Mass Air Flow Meter)ECM
L-B
W
E5 E5
- DIAGNOSTICSENGINE
DI-29
185 Author
: Date
:
2001 AVALON (RM808U)
WIRING DIAGRAM
INSPECTION PROCEDURE
HINT:

If DTCs P0110, P0115, P0120 and P1410 are output simultaneously, E2 (sensor ground) may be open.

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 intake
air temperature.
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.
CHECK:
Read the temperature value on the OBD II scan tool or TOYOTA hand-held tester.
OK:
Same as actual intake air temperature.
HINT:

If there is open circuit, OBD II scan tool or TOYOTA hand-held tester indicates -40°C (-40°F).

If there is short circuit, OBD II scan tool or TOYOTA hand-held tester indicates 140°C (284°F) or more.
NG -40°C (-40°F) ... Go to step 2.
140°C (284°F) or more ... Go to step 4.
OK
Check for intermittent problems
(See page DI-3).

A00310
A09772
Engine Coolant Temp. SensorECM
5 V
THW
E2
E1 14
18 2
1G-Y
W
E5 E5 DI-32
- DIAGNOSTICSENGINE
188 Author
: Date
:
2001 AVALON (RM808U)
DTC P0115 Engine Coolant Temp. Circuit Malfunction
CIRCUIT DESCRIPTION
A thermistor built into the engine coolant temperature sensor changes the resistance value according to the
engine coolant temperature.
The structure of the sensor and connection to the ECM is the same as in the intake air temperature circuit
malfunction shown on page DI-28.
If the ECM detects the DTC P0115, it operates the fail-safe function in which the engine coolant temperature
is assumed to be 80°C (176°C).
DTC No.DTC Detecting ConditionTrouble Area
P0115Open or short in engine coolant temp. sensor circuit

Open or short in engine coolant temp. sensor circuit

Engine coolant temp. sensor

ECM
HINT:
After confirming DTC P0115, use the OBD II scan tool or TOYOTA hand-held tester to confirm the engine
coolant temperature from the CURRENT DATA.
Temperature DisplayedMalfunction
-40°C (-40°F)Open circuit
140°C (284°F) or moreShort circuit
WIRING DIAGRAM
INSPECTION PROCEDURE
HINT:

If DTCs P0110, P0115, P0120 and P1410 are output simultaneously, E2 (sensor ground) may be open.

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.
DI07I-09

P24296
ECM
Throttle Position
Sensor
VC
VTA
E2
S05019A09773
ECM
1
3
22
23
185 V
VC
VTA1
E2 L-R
LG
W Throttle Position Sensor
E5 E5 E5 DI-38
- DIAGNOSTICSENGINE
194 Author
: Date
:
2001 AVALON (RM808U)
DTC P0120 Throttle/Pedal position Sensor/Switch ºAº
Circuit Malfunction
CIRCUIT DESCRIPTION
The throttle position sensor is mounted in the throttle body and
detects the throttle valve opening angle. When the throttle valve
is fully closed, a voltage of approximately 0.7 V is applied to ter-
minal VTA of the ECM. The voltage applied to terminals VTA of
the ECM increases in proportion to the opening angle of the
throttle valve and becomes approximately 2.7 - 5.2 V when the
throttle valve is fully opened. The ECM judges the vehicle driv-
ing conditions from these signals input from terminals VTA and
uses them as one of the conditions for deciding the air-fuel ratio
correction, power increase correction and fuel-cut control etc.
DTC No.DTC Detecting ConditionTrouble Area
P0120
Condition (a) or (b) continues:
(a) VTA
0.1 V
(b) VTA
4.9 V

Open or short in throttle position sensor circuit

Throttle position sensor

ECM
HINT:
After confirming DTC P0120, use the OBD II scan tool or TOYOTA hand-held tester to confirm the throttle
valve opening percentage and closed throttle position switch condition.
Throttle valve opening position expressed as percentageTblAThrottle valve fully closedThrottle valve fully openTrouble Area
0 %0 %
VC circuit open

VTA circuit open or short
Approx. 100 %Approx. 100 %
E2 circuit open
WIRING DIAGRAM
INSPECTION PROCEDURE
HINT:

If DTCs P0110, P0115 and P0120 are output simultaneously, E2 (sensor ground) bay be open.
DI6T1-01

A11670
HTS
E03 AFR+
3.3 VECM
to Analog-Digital
Converter
to Analog-Digital
Converter
AFR-
AFL+ HAFR
3.3 V3.0 V
AFL-
OXSHAFL
3.0 VE04
E05
E1 E79
8 4
213
1220 11 E5
E5
E5
E5
E5
E5
E7
L-O
LG
B
B-R
L
B-W
BR
B-RB-R
LG
B B-W
B-W
B-W
B-W
B-W
BR
BR B From
Battery
From Terminal
MREL of ECMA/F Sensor
(Bank 1
Sensor 1)
J5 J/C
J7 J/CA/F Sensor
(Bank 2
Sensor 1)
Heated
Oxygen
Sensor
(Bank 1
Sensor 2)2
3
41
2
3
41
2
3
41 23
5
1
23
5
1 A/F Relay
EFI Relay Engine Room J/B
16
19
IK28 16
IK2 IK2II2
EC
1021
IK2
II2
EB
A
A
A12
13
9
2B
4 2B 2B2B
4 2FA/F
EFI
No.2 2
2GEFI
No.1
W-B
ED
BR
BR
BRBR B
B DI-44
- DIAGNOSTICSENGINE
200 Author
: Date
:
2001 AVALON (RM808U)

OBD II scan tool (excluding TOYOTA hand-held tester) displays the one fifth of the A/F sensor output
voltage which is displayed on the TOYOTA hand-held tester.
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.