2001 TOYOTA AVALON Wiring diagram

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.

- DIAGNOSTICSENGINE
DI-49
205 Author
: Date
:
2001 AVALON (RM808U)
DTC P0136 Oxygen Sensor Circuit Malfunction (Bank 1
Sensor 2)
CIRCUIT DESCRIPTION
Refer to DTC P0125 on page DI-43.
DTC No.DTC Detecting ConditionTrouble Area
P0136
Voltage output of heated oxygen sensor remains at 0.4 V or
more or 0.55 V or less when vehicle is driven at 50 km/h (31
mph) or more after engine is warmed up (2 trip detection logic)
Open or short in heated oxygen sensor circuit

Heated oxygen sensor
HINT:

Bank 1 refers to the bank that includes cylinder No.1.

Sensor 2 refers to the sensor farther away from the engine body.
WIRING DIAGRAM
Refer to DTC P0125 on page DI-43.
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 Are there any other codes (besides DTC P0136) being output?
YES Go to relevant DTC chart (See page DI-14).
NO
2 Check for open and short in harness and connector between ECM and heated
oxygen sensor (See page IN-30).
NG Repair or replace harness or connector.
OK
DI07Q-09

A06104
ON
HTS
(+)
(-)
- DIAGNOSTICSENGINE
DI-51
207 Author
: Date
:
2001 AVALON (RM808U)
DTC P0141 Oxygen Sensor Heater Circuit Malfunction
(Bank 1 Sensor 2)
CIRCUIT DESCRIPTION
Refer to DTC P0125 on page DI-43.
DTC No.DTC Detecting ConditionTrouble Area
P0141
When heater operates, heater current exceeds 2.35 A (2 trip
detection logic)
Open or short in heater circuit of heated oxygen sensor
Htd htP0141Heater current of 0.2 A or less when heater operates (2 trip
detection logic)
Heated oxygen sensor heater

ECM
HINT:

Bank 1 refers to the bank that includes cylinder No.1.

Sensor 2 refers to the sensor farther away from the engine body.
WIRING DIAGRAM
Refer to DTC P0125 on page DI-43.
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 Check voltage between terminal HTS 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 terminal HTS of the ECM con-
nector and body ground.
OK:
Voltage: 9 - 14 V
OK Check and replace ECM (See page IN-30).
NG
2 Check resistance of heated oxygen sensor heater (See page SF-81).
NG Replace heated oxygen sensor.
DI6T3-01

A11083
Fusible
Link Block
Battery FL
MainB-O
B-W
2
2
2
2
2
21
1
1
1
1
1L
R
Y
W
GE5
IG Switch
No.1
No.2
No.3
No.4
No.5
No.6
Injector
W-B
ED
5
6
21
311
2
3
4#10
#20
#30
#40
#50
#60
E01
E02ECM
112B
2G
AM2
41 B
F6F7
11J
67
IF1 1C
2CIG23
5
W-RE4
E4
E4
E4
E4
E4E5
W-B
B-W
B-W
B-W
B-W
B-W22
2
2C2F
7
7
W-R
4
1
B
Driver Side J/BEngine Room J/B
W-B
EB
G DDL J8
J/C
B-WB-W B-WB-W B-W
IG2 Relay
W-B
B-O2
- DIAGNOSTICSENGINE
DI-59
215 Author
: Date
:
2001 AVALON (RM808U)
HINT:
When the 2 or more codes for a misfiring cylinder are recorded repeatedly but no Random Misfire code is
recorded, it indicates that the misfires were detected and recorded at different times.
WIRING DIAGRAM
CONFIRMATION DRIVING PATTERN
(a) Connect the TOYOTA hand-held tester or OBD II scan tool.
(b) Record the DTC and the freeze frame data.
(c) Use the TOYOTA hand-held tester to set to the check mode (See page DI-3).
(d) Drive the vehicle several times with the engine speed, load and its surrounding range shown with the
ENGINE SPD, CALC LOAD in the freeze frame data or the MISFIRE RPM, MISFIRE LOAD in the data
list.
If you have no TOYOTA hand-held tester, turn the ignition switch OFF after the symptom is simulated the
first time. Then repeat the simulation process again.
HINT:
In order to memorize DTC of misfire, it is necessary to drive around MISFIRE RPM, MISFIRE LOAD in the
data list for the following period of time.
Engine SpeedTime
Idling3 minutes 30 seconds or more
1,000 rpm3 minutes or more
2,000 rpm1 minute 30 seconds or more
3,000 rpm1 minute or more