DI-43 TOYOTA AVALON 2001 Service Repair Manual

A00477
Atmosphere
Cover
Exhaust GasPlatinum
Electrode
Solid Electrolyte
(Zirconia Element)
Platinum
Electrode
Heater
A/F Sensor Voltage
Air-Fuel Ratio
(V)
2.6 4.0
3.8
3.6
3.4
3.2
3.0
2.8
2.4
12 13 14 15 16 17 18
Coating (Ceramic)
ECM Monitored
19
Housing
- DIAGNOSTICSENGINE
DI-43
199 Author
: Date
:
2001 AVALON (RM808U)
DTC P0125 Insufficient Coolant Temp. for Closed Loop
Fuel Control
CIRCUIT DESCRIPTION
To obtain a high purification rate for the CO, HC and NOx components of the exhaust gas, a three-way cata-
lytic converter is used, but for the most efficient use of the three-way catalytic converter, the air-fuel ratio
must be precisely controlled so that it is always close to the stoichiometric air-fuel ratio.
The A/F sensor has the characteristic that provides output voltage* approximately proportional to the exist-
ing air-fuel ratio. The A/F sensor output voltage* is used to provide feedback for the ECM to control the air-
fuel ratio.
By the A/F sensor output, the ECM can determine the deviation amount from the stoichiometric air-fuel ratio
and control the proper injection time immediately. If the A/F sensor is malfunctioning, ECM is unable to per-
form accurate air-fuel ratio control.
The A/F sensor is equipped with a heater which heats the zirconia element. The heater is controlled by the
ECM. When the intake air volume is low (the temp. of the exhaust gas is low), current flows to the heater
to heat the sensor for accurate oxygen concentration detection.
*: The voltage value changes at the inside of the ECM only.
DTC No.DTC Detecting ConditionTrouble Area
P0125
After engine is warmed up, A/F sensor output* does not
change when conditions (a), (b), (c) and (d) continue for at
least 1.5 min:
*: Output value changes at inside of the ECM only
(a) Engine speed: 1,500 rpm or more
(b) Vehicle speed: 40 - 100 km/h (25 - 62 mph)
(c) Throttle valve is not fully closed
(d) 140 sec. or more after starting engine
Open or short in A/F sensor (bank 1, 2 sensor 1) circuit

A/F sensor (bank 1, 2 sensor 1)

Air inducation system

Fuel pressure

Injector

Gas leakage on exhaust sytem

ECM
HINT:

After confirming DTC P0125, use the OBD II scan tool or TOYOTA hand-held tester to confirm voltage
output of the A/F sensor (bank 1, 2 sensor 1) from the CURRENT DATA.

The ECM controls the voltage of the AFR+, AFL+, AFR- and AFL- terminals of the ECM to the fixed
voltage. Therefore, it is impossible to confirm the A/F sensor output voltage without the OBDII scan
tool or TOYOTA hand-held tester.
DI07M-14

- 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

DI-106
- DIAGNOSTICSENGINE
262 Author
: Date
:
2001 AVALON (RM808U)
DTC P1130 A/F Sensor Circuit Range/Performance Mal-
function (Bank 1 Sensor 1)
DTC P1150 A/F Sensor Circuit Range/Performance Mal-
function (Bank 2 Sensor 1)
CIRCUIT DESCRIPTION
Refer to DTC P0125 on page DI-43.
DTC No.DTC Detecting ConditionTrouble Area
Voltage output* of A/F sensor remains at 3.8 V or more, or 2.8
V or less, during engine running after the engine is warmed up
(2 trip detection logic)
*: Output value changes at inside of ECM only

Open or short in A/F sensor circuit

A/F sensor
P1130
P1150Voltage output* of A/F sensor does not change from 3.30 V,
during engine running after the engine is warmed up (2 trip
detection logic)
*: Output value changes at the inside of ECM only
Air induction system

Fuel pressure

Injector

ECM
Open or short in A/F sensor circuit (2 trip detection logic)
HINT:

After confirming DTC P1130, use the OBD II scan tool or TOYOTA hand-held tester to confirm voltage
output of A/F sensor (AFS B1 S1/O2S B1 S1) from the CURRENT DATA.

The A/F sensor's output voltage and the short-term fuel trim value can be read using the OBD II scan
tool or TOYOTA hand-held tester.

The ECM controls the voltage of the AFR+, AFL+, AFR- and AFL- terminals of the ECM to the fixed
voltage. Therefore, it is impossible to confirm the A/F sensor output voltage without the OBDII scan
tool or TOYOTA hand-held tester.

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
Refer to DTC P0125 on page DI-43.
DI2H7-03

- DIAGNOSTICSENGINE
DI-1 11
267 Author
: Date
:
2001 AVALON (RM808U)
DTC P1133 A/F Sensor Circuit Response Malfunction
(Bank 1 Sensor 1)
DTC P1153 A/F Sensor Circuit Response Malfunction
(Bank 2 Sensor 1)
CIRCUIT DESCRIPTION
Refer to DTC P0125 on page DI-43.
DTC No.DTC Detecting ConditionTrouble Area
P1133
P1153
After engine is warmed up, and during vehicle driving at engine
speed 1,400 rpm or more and vehicle speed 60 km/h (38 mph)
or more, if the response characteristic of A/F sensor becomes
deteriorated (2 trip detection logic)

Open or short in A/F sensor circuit

A/F sensor

Air induction system

Fuel pressure

Injector

ECM
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 P1133, P1153) being output?
YES Go to relevant DTC chart (See page DI-14).
NO
2 Connect OBDII scan tool or TOYOTA hand-held tester, and read value for volt-
age output of A/F sensor.
PREPARATION:
(a) Connect the OBD II scan tool or TOYOTA hand-held tester to the DLC3.
(b) Warm up the A/F sensor with the engine speed at 2,500 rpm for approx. 90 sec.
CHECK:
Read the voltage of the A/F sensor on the screen of the OBD II scan tool or TOYOTA hand-held tester when
you perform all the following conditions.
DI2H8-03

A02032
HAFL ON
HAFR
(+)
(-)
- DIAGNOSTICSENGINE
DI-1 15
271 Author
: Date
:
2001 AVALON (RM808U)
DTC P1135 A/F Sensor Heater Circuit Malfunction (Bank
1 Sensor 1)
DTC P1155 A/F Sensor Heater Circuit Malfunction (Bank
2 Sensor 1)
CIRCUIT DESCRIPTION
Refer to DTC P0125 on page DI-43.
DTC No.DTC Detecting ConditionTrouble Area
P1135
When the heater operates, heater current exceeds 8 A
(2 trip detection logic)
Open or short in heater circuit of A/F sensor
A/F h tP1135
P1155Heater current of 0.25 A or less when the heater operates
(2 trip detection logic)
A/F sensor heater

ECM
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 terminals HAFL, HAFR 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 terminals HAFL, HAFR of the
ECM connector and body ground.
OK:
Voltage: 9 - 14 V
OK Check and replace ECM (See page IN-30).
NG
2 Check resistance of A/F sensor heater (See page SF-79).
DI2H9-03

DI-54
- DIAGNOSTICSENGINE
210 Author
: Date
:
HINT:

When the DTC P0171 or P0174 is recorded, the actual air-fuel ratio is on the lean side. When DTC
P0172 or P0175 is recorded, the actual air-fuel ratio is on the rich side.

If the vehicle runs out of fuel, the air-fuel ratio is lean and DTC P0171 or P0174 is recorded. The MIL
then comes on.

If the total of the short-term fuel trim value and the long-term fuel trim value is within + 35 % (80°C
(176°F) or more), the system is functioning normally.

The A/F sensors (bank 1, 2 sensor 1) output voltage and the short-term fuel trim value can be read
using the OBD II scan tool or hand-held tester.

The ECM controls the voltage of AFR+, AFL+, AFR- and AFL- terminals of ECM to the fixed voltage.
Therefore, it is impossible to confirm the A/F sensor output voltage without OBD II scan tool or hand-
held tester.

OBD II scan tool (excluding hand-held tester) displays the one fifth of the A/F sensors (bank 1, 2 sen-
sor 1) output voltage which is displayed on the hand-held tester.
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 air induction system (See page SF-1).
NG Repair or replace.
OK
2 Check injector injection (See page SF-23).
NG Replace injector.
OK

DI07B-20
DI-14
- DIAGNOSTICSENGINE
170 Author
: Date
:
DIAGNOSTIC TROUBLE CODE CHART
HINT:
Parameters listed in the chart may not be exactly the same as your reading due to the type of instrument
or other factors.
If a malfunction code is displayed during the DTC check in check mode, check the circuit for the codes listed
in the table below. For details of each code, turn to the page referred to under the ''See page '' for the respec-
tive ''DTC No.'' in the DTC chart.
SAE CONTROLLED
DTC No.
(See page)Detection ItemTrouble AreaMIL*1Memory
P0100
(DI-23)Mass Air Flow Circuit Malfunc-
tionOpen or short in mass air flow meter circuit
Mass air flow meter
ECM

P0101
(DI-27)Mass Air Flow Circuit Range/
Performance ProblemMass air flow meter
P0110
(DI-28)Intake Air Temp. Circuit Malfunc-
tionOpen or short in intake air temp. sensor circuit
Intake air temp. sensor (built into mass air flow meter)
ECM

P0115
(DI-32)Engine Coolant Temp. Circuit
MalfunctionOpen or short in engine coolant temp. sensor circuit
Engine coolant temp. sensor
ECM

P0116
(DI-36)Engine Coolant Temp. Circuit
Range/Performance ProblemCooling system
Engine coolant temp. sensor
P0120
(DI-38)Throttle/Pedal Position Sensor/
Switch ºAº Circuit MalfunctionOpen or short in throttle position sensor circuit
Throttle position sensor
ECM

P0121
(DI-42)Throttle/Pedal Position Sensor/
Switch ºAº Circuit Range/Perfor-
mance Problem
Throttle position sensor
P0125
(DI-43)Insufficient Coolant Temp. for
Closed Loop Fuel Control
Open or short in A/F sensor (bank 1, 2 sensor 1) circuit
A/F sensor (bank 1, 2 sensor 1)
Air induction system
Fuel pressure
Injector
Gas leakage on exhaust system
ECM

P0128
(DI-48)Thermostat Malfunction
Thermostat
Cooling system
Engine coolant temp. sensor
ECM
P0136
(DI-49)Oxygen Sensor Circuit Malfunc-
tion (Bank 1 Sensor 2)Open or short in heated oxygen sensor circuit
Heated oxygen sensor
P0141
(DI-51)Oxygen Sensor Heater Circuit
Malfunction (Bank 1 Sensor 2)Open or short in heater circuit of heated oxygen sensor
Heated oxygen sensor heater
ECM


H01021AB0118AB0119R13006H01081H01211
"u
E1 TcACC ON
orAirbag
Sensor
Assembly P/T Squib (RH)
DTC B0133/62 DLC1
DI-430
- DIAGNOSTICSSUPPLEMENTAL RESTRAINT SYSTEM
586 Author
: Date
:
2001 AVALON (RM808U)
4 Check P/T squib (RH).
PREPARATION:
(a) Turn ignition switch to LOCK.
(b) Disconnect negative (-) terminal cable from the battery,
and wait at least for 90 seconds.
(c) Connect the seat belt pretensioner (RH) connector.
(d) Connect negative (-) terminal cable to the battery, and
wait at least for 2 seconds.
CHECK:
(a) Turn the ignition switch to ACC or ON, and wait at least
for 20 seconds.
(b) Clear the DTC stored in memory
(See step 5 on page DI-349).
(c) Turn the ignition switch to LOCK, and wait at least for 20
seconds.
(d) Turn the ignition switch to ACC or ON, and wait at least
for 20 seconds.
(e) Check the DTC (See page DI-349).
OK:
DTC B0133/62 is not output.
HINT:
Codes other than code B0133/62 may be output at this time, but
they are not relevant to this check.
NG Replace seat belt pretensioner (RH).
OK
From the results of the above inspection, the malfunctioning part can now be considered normal.
To make sure of this, use the simulation method to check. If the malfunctioning part can not be
detected by the simulation method, replace all SRS components including the wire harness.

H01454
P/T Squib (LH)
PL+
PL- 1
21 2
C5
C5 Y-B
YAirbag Sensor Assembly
- DIAGNOSTICSSUPPLEMENTAL RESTRAINT SYSTEM
DI-431
587 Author
: Date
:
2001 AVALON (RM808U)
DTC B0135/73 Short in P/T Squib (LH) Circuit
CIRCUIT DESCRIPTION
The P/T squib (LH) circuit consists of the airbag sensor assembly and seat belt pretensioner (LH).
It causes the SRS to deploy when the SRS deployment conditions are satisfied.
For details of the function of each component, see OPERATION on page RS-3.
DTC B0135/73 is recorded when a short is detected in the P/T squib (LH) circuit.
DTC No.DTC Detecting ConditionTrouble Area
B0135/73

Short circuit between PL+ wire harness and PL- wire har-
ness of squib

P/T squib (LH) malfunction

Airbag sensor assembly malfunction
Seat belt pretensioner (LH)

Airbag sensor assembly

Wire harness
WIRING DIAGRAM
DI4D4-03