2001 TOYOTA AVALON OBD port

DI02C-06
Mechanical System Test
P. DI-160NG
Customer Problem Analysis Vehicle Brought to Workshop
Check DTC and Freeze Frame Data (Pre-check)Items inside
P. DI-159are titles of pages in this manual, with the
page number indicated in the bottom portion. See the indicated
pages for detailed explanations.
Connect an OBD II scan tool or TOYOTA hand-held tester to DLC3.
If the display shows ºUNABLE TO CONNECT TO VEHICLEº when you have connected the
scan tool / TOYOTA hand-held tester, inspect DLC3 P. DI-160
Record or Print DTC and Freeze Frame Data P. DI-160
Clear DTC and Freeze Frame Data P. DI-160
Symptom does not occur
Problem Symptom Confirmation
P. DI-160 Symptom Simulation
Symptom occurs
P. DI-160 OK Code
DTC Check
P. DI-160
DTC Chart
P. DI-172Basic Inspection
Manual Shifting TestOK
P. DI-160NG
NG
NG NG
NG OKOK
OKOK Matrix Chart of Problem Symptoms - P. DI-175
Chapter 1
(Electronic)Chapter 2
(On-V ehicle)
P. DI-175
P. DI-175Chapter 3
(Off-V ehicle)
P. DI-175
Circuit
Inspection
O/D Cancel Signal Check

O/D Main Switch & O/D OFF Indicator Light Check
P. DI-203 to DI-206
Identification of ProblemParts Inspection
End
Confirmation Test
Repair Setting the Check Mode Diagnosis P. DI-160 Visual Inspection1
5
9
16 2
6
10
15 3
7
11
14 4
8
12
13
17
DI-158
- DIAGNOSTICSAUTOMATIC TRANSAXLE
314 Author
: Date
:
2001 AVALON (RM808U)
AUTOMATIC TRANSAXLE
HOW TO PROCEED WITH TROUBLESHOOTING

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

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

DI078-07
Vehicle Brought to Workshop
Customer Problem Analysis P. DI-2
Problem Symptom Confirmation
If the engine does not start, perform steps 10 and 12 firstConnect the OBD II scan tool or TOYOTA hand-held tester to DLC3 P. DI-3
If the display indicates a communication fault in the tool, inspect DLC3 P. DI-3

Check DTC and Freezed Frame Data (Precheck)
Record or Print DTC and Freezed Frame Data P. DI-3
Clear DTC and Freezed Frame Data P. DI-3
Visual Inspection
Setting the Check Mode Diagnosis P. DI-3
Symptom Simulation P. IN-20
DTC Chart P. DI-14
Problem Symptoms Table P. DI-22
Circuit Inspection P. DI-23
Adjustment, Repair
DTC Check P. DI-3
Titles insideare titles of pages in
in the bottom portion. See the indicated
pages for detailed explanations.this manual with the page number indicated
Malfunction
occurs.Malfunction does not occur.
Parts Inspection
Check for Intermittent Problems P. DI-3
Identification of Problem
Confirmation Test
End 1
2
3
4
5
6
7
108
9
11
12
13
15 14
16
Normal Malfunction code.
17Basic Inspection P. DI-3
- DIAGNOSTICSENGINE
DI-1
157 Author
: Date
:
2001 AVALON (RM808U)
ENGINE
HOW TO PROCEED WITH TROUBLESHOOTING
Troubleshoot in accordance with the procedure on the following page.

- INTRODUCTIONTERMS
IN-41
41 Author
: Date
:
2001 AVALON (RM808U) HO2S
Heated Oxygen SensorHeated Oxygen Sensor (HO2S)
IACIdle Air ControlIdle Speed Control (ISC)
IATIntake Air TemperatureIntake or Inlet Air Temperature
ICMIgnition Control Module-
IFIIndirect Fuel InjectionIndirect Injection (IDL)
IFSInertia Fuel-Shutoff-
ISCIdle Speed Control-
KSKnock SensorKnock Sensor
MAFMass Air FlowAir Flow Meter
MAPManifold Absolute PressureManifold Pressure
Intake Vacuum
MCMixture Control
Electric Bleed Air Control Valve (EBCV)
Mixture Control Valve (MCV)
Electric Air Control Valve (EACV)
MDPManifold Differential Pressure-
MFIMultiport Fuel InjectionElectronic Fuel Injection (EFI)
MILMalfunction Indicator LampCheck Engine Lamp
MSTManifold Surface Temperature-
MVZManifold Vacuum Zone-
NVRAMNon-V olatile Random Access Memory-
O2SOxygen SensorOxygen Sensor, O2 Sensor (O2S)
OBDOn-Board DiagnosticOn-Board Diagnostic System (OBD)
OCOxidation Catalytic ConverterOxidation Catalyst Convert (OC), CCo
OPOpen LoopOpen Loop
PAIRPulsed Secondary Air InjectionAir Suction (AS)
PCMPowertrain Control Module-
PNPPark/Neutral Position-
PROMProgrammable Read Only Memory-
PSPPower Steering Pressure-
PTOXPeriodic Trap OxidizerDiesel Particulate Filter (DPF)
Diesel Particulate Trap (DPT)
RAMRandom Access MemoryRandom Access Memory (RAM)
RMRelay Module-
ROMRead Only MemoryRead Only Memory (ROM)
RPMEngine SpeedEngine Speed
SCSuperchargerSupercharger
SCBSupercharger BypassE-ABV
SFISequential Multiport Fuel InjectionElectronic Fuel Injection (EFI), Sequential Injection
SPLSmoke Puff Limiter-
SRIService Reminder Indicator-
SRTSystem Readiness Test-
STScan Tool-
TBThrottle BodyThrottle Body
TBIThrottle Body Fuel InjectionSingle Point Injection
Central Fuel Injection (Ci)
TCTurbochargerTurbocharger
TCCTorque Converter ClutchTorque Converter