ECU TOYOTA AVENSIS 1999 Supplement

INTRODUCTION
HOW TO USE THIS MANUAL IN–1. . . . . . . . . . . . .
GENERAL INFORMATION IN–1. . . . . . . . . . . . . . . . . .
IDENTIFICATION INFORMATION IN–3. . . . . . . . . .
VEHICLE IDENTIFICATION AND ENGINE SERIAL
NUMBER IN–3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
REPAIR INSTRUCTIONS IN–4. . . . . . . . . . . . . . . . .
GENERAL INFORMATION IN–4. . . . . . . . . . . . . . . . . .
VEHICLE LIFT AND SUPPORT LOCATIONS IN–7. .
FOR ALL OF VEHICLES IN–9. . . . . . . . . . . . . . . . . .
PRECAUTION IN–9. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
HOW TO TROUBLESHOOT ECU CONTROLLED
SYSTEMS IN–18. . . . . . . . . . . . . . . . . . . . . . . . . . . .
GENERAL INFORMATION IN–18. . . . . . . . . . . . . . . . . .
HOW TO PROCEED
WITH TROUBLESHOOTING IN–19. . . . . . . . . . . . . .
HOW TO USE THE DIAGNOSTIC CHART AND
INSPECTION PROCEDURE IN–29. . . . . . . . . . . . . . .
TERMS IN–34. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ABBREVIATIONS USED IN THIS MANUAL IN–34. . . .

FI1066
IN03Z–01
IN–4
– INTRODUCTIONREPAIR INSTRUCTIONS
REPAIR INSTRUCTIONS
GENERAL INFORMATION
BASIC REPAIR HINT
(a) Use fender, seat and floor covers to keep the vehicle
clean and prevent damage.
(b) During disassembly, keep parts in the appropriate order
to facilitate reassembly.
(c) Installation and removal of battery terminal:
(1) Before performing electrical work, disconnect the
negative (–) terminal cable from the battery.
(2) If it is necessary to disconnect the battery for in-
spection or repair, first disconnect the negative (–)
terminal.
(3) When disconnecting the terminal cable, to prevent
damage to the battery terminal, loosen the cable
nut and raise the cable straight up without twisting
or prying it.
(4) Clean the battery terminals and cable ends with a
clean shop rag. Do not scrape them with a file or oth-
er abrasive objects.
(5) Install the cable ends to the battery terminals after
loosening the nut and tighten the nut after installa-
tion. Do not use a hammer to tap the cable ends
onto the terminals.
(6) Be sure the cover for the positive (+) terminal is
properly in place.
(d) Check hose and wiring connectors to make sure that they
are connected securely and correctly.
(e) Non–reusable parts
(1) Always replace cotter pins, gaskets, O–rings and oil
seals, etc. with new ones.
(2) Non–reusable parts are indicated in the component
illustrations by the ”
” symbol.
(f) Precoated parts
Precoated parts are bolts and nuts, etc. that are coated
with a seal lock adhesive at the factory.
(1) If a precoated part is retightened, loosened or
caused to move in any way, it must be recoated with
the specified adhesive.
(2) When reusing precoated parts, clean off the old
adhesive and dry with compressed air. Then apply
the specified seal lock adhesive to the bolt, nut or
threads.
(3) Precoated parts are indicated in the component il-
lustrations by the ”” symbol.
(g) When necessary, use a sealer on gaskets to prevent
leaks.

IN0253
WRONG CORRECT
IN0252
WRONG CORRECT
IN0002
Example IN–6
– INTRODUCTIONREPAIR INSTRUCTIONS
(2) After the vehicle is jacked up, be sure to support it
on stands. It is extremely dangerous to do any work
on a vehicle raised on a jack alone, even for a small
job that can be finished quickly.
(l) Observe the following precautions to avoid damage to the
following parts:
(1) Do not open the cover or case of the ECU unless
absolutely necessary. (If the IC terminals are
touched, the IC may be destroyed by static electric-
ity.)
(2) To disconnect vacuum hoses, pull off the end, not
the middle of the hose.
(3) To pull apart electrical connectors, pull on the con-
nector itself, not the wires.
(4) Be careful not to drop electrical components, such
as sensors or relays. If they are dropped on a hard
floor, they should be replaced and not reused.
(5) When steam cleaning an engine, protect the elec-
tronic components, air filter and emission–related
components from water.
(6) Never use an impact wrench to remove or install
temperature switches or temperature sensors.
(7) When checking continuity at the wire connector, in-
sert the tester probe carefully to prevent terminals
from bending.
(8) When using a vacuum gauge, never force the hose
onto a connector that is too large. Use a step–down
adapter for adjustment. Once the hose has been
stretched, it may leak air.
(m) Installation and removal of vacuum hose:
(1) When disconnecting vacuum hoses, use tags to
identify where they should be reconnected to.
(2) After completing a job, double check that the vacu-
um hoses are properly connected. A label under the
hood shows the proper layout.
(n) Unless otherwise stated, all resistance is measured at an
ambient temperature of 20
C (68
F). Because the resis-
tance may be outside specifications if measured at high
temperatures immediately after the vehicle has been run-
ning, measurement should be made when the engine has
cooled down.

IN–16
– INTRODUCTIONFOR ALL OF VEHICLES
2. FOR VEHICLES EQUIPPED WITH A CATALYTIC CONVERTER
CAUTION:
If large amount of unburned gasoline flows into the converter, it may overheat and create a fire haz-
ard. To prevent this, observe the following precautions and explain them to your customer.
(a) Use only unleaded gasoline.
(b) Avoid prolonged idling.
Avoid running the engine at idle speed for more than 20 minutes.
(c) Avoid spark jump test.
(1) Perform spark jump test only when absolutely necessary. Perform this test as rapidly as possible.
(2) While testing, never race the engine.
(d) Avoid prolonged engine compression measurement.
Engine compression tests must be done as rapidly as possible.
(e) Do not run engine when fuel tank is nearly empty.
This may cause the engine to misfire and create an extra load on the converter.
(f) Avoid coasting with ignition turned off and prolonged braking.
(g) Do not dispose of used catalyst along with parts contaminated with gasoline or oil.
3. IF VEHICLE IS EQUIPPED WITH MOBILE COMMUNICATION SYSTEM
For vehicles with mobile communication systems such as two–way radios and cellular telephones, observe
the following precautions.
(a) Install the antenna as far as possible away from the ECU and sensors of the vehicle’s electronic sys-
tem.
(b) Install the antenna feeder at least 20 cm (7.87 in.) away from the ECU and sensors of the vehicle’s
electronic systems. For details about ECU and sensors locations, refer to the section on the applicable
component.
(c) Do not wind the antenna feeder together with the other wiring as much as possible, also avoid running
the antenna feeder parallel with other wire harnesses.
(d) Check that the antenna and feeder are correctly adjusted.
(e) Do not install powerful mobile communications system.
4. FOR USING HAND–HELD TESTER
CAUTION:
Observe the following items for safety reasons:
Before using the hand–held tester, the hand–held tester’s operator manual should be read thor-
oughly.
Be sure to route all cables securely when driving with the hand–held tester connected to the
vehicle. (i.e. Keep cables away from feet, pedals, steering wheel and shift lever.)
Two persons are required when test driving with the hand–held tester, one person to drive the
vehicle and the other person to operate the hand–held tester.

IN00Z–24
IN–18– INTRODUCTIONHOW TO TROUBLESHOOT ECU CONTROLLED
SYSTEMS
HOW TO TROUBLESHOOT ECU CONTROLLED SYSTEMS
GENERAL INFORMATION
A large number of ECU controlled systems are used in the AVENSIS/CORONA. In general, the ECU con-
trolled system is considered to be a very intricate system requiring a high level of technical knowledge and
expert skill to troubleshoot. However, the fact is that if you proceed to inspect the circuits one by one, trouble-
shooting of these systems is not complex. If you have adequate understanding of the system and a basic
knowledge of electricity, accurate diagnosis and necessary repair can be performed to locate and fix the
problem. This manual is designed through emphasis of the above standpoint to help service technicians
perform accurate and effective troubleshooting, and is compiled for the following major ECU controlled sys-
tems:
The troubleshooting procedure and how to make use of it are described on the following pages.
SystemPage
Supplemental Restraint SystemDI–1
FOR USING HAND–HELD TESTER
Before using the hand–held tester, the hand–held tester’s operator manual should be read thoroughly.
If the hand–held tester cannot communicate with ECU controlled systems when you have connected
the cable of the hand–held tester to DLC3, turned the ignition switch ON and operated the scan tool,
there is a problem on the vehicle side or tool side.
(1) If communication is normal when the tool is connected to another vehicle, inspect the diagnosis
data link line (Busline) or ECU power circuit of the vehicle.
(2) If communication is still not possible when the tool is connected to another vehicle, the problem
is probably in the tool itself, so perform the Self Test procedures outline in the Tester Operator’s
Manual.

IN06D–07
Vehicle Brought to Workshop
Customer Problem
Analysis
Symptom Confirmation
and Diagnostic Trouble
Code Check
Symptom Simulation
Diagnostic Trouble
Code Chart
Problem Symptoms Table
Circuit Inspection or Parts
Inspection
Repair
Confirmation Test
End 1
2
43
5
6
7
8Ask the customer about the conditions and the
environment when the problem occurred.1
Confirm the symptoms and the problem conditions,
and check the diagnostic trouble codes.
(When the problem symptoms do not appear
during confirmation, use the symptom simulation
method described later on.)2, 3
Check the results obtained in Step 2, then confirm
the inspection procedure for the system or the part
which should be checked using the diagnostic
trouble code chart or the problem symptoms table.4, 5, 6
Check and repair the affected system or part in
accordance with the instructions in Step 6. 7
After completing repairs, confirm that the problem
has been eliminated.
(If the problem is not reproduced, perform the
confirmation test under the same conditions and
in the same environment as when it occurred for
the first time.)8
– INTRODUCTIONHOW TO TROUBLESHOOT ECU CONTROLLED
SYSTEMSIN–19
HOW TO PROCEED WITH TROUBLESHOOTING
Carry out troubleshooting in accordance with the procedure on the following page. Here, only the basic pro-
cedure is shown. Details are provided in DI section, showing the most effective methods for each circuit.
Confirm the troubleshooting procedures first for the relevant circuit before beginning troubleshooting of that
circuit.

Important Points in the Customer Problem Analysis
 What ––––– Vehicle model, system name
 When ––––– Date, time, occurrence frequency
 Where ––––– Road conditions
 Under what conditions? ––––– Running conditions, driving conditions, weather conditions
 How did it happen? ––––– Problem symptoms
(Sample) Supplemental restraint system check sheet.
Supplemental Restraint System Check Sheet
Customer’s Name
Date Vehicle Brought In
Registration No.
Frame No.
Odometer Reading
km
miles
Date Problem First Occurred
Weather
Temperature
Vehicle OperationFine Cloudy
StartingIdling
Driving
Constant speed Acceleration
OtherInspector’s
Name
CUSTOMER PROBLEM ANALYSIS CHECK
Registration Year
RainySnowyOther / / / /
/ /
Approx.
Deceleration [
]
IN–20– INTRODUCTIONHOW TO TROUBLESHOOT ECU CONTROLLED
SYSTEMS
1. CUSTOMER PROBLEM ANALYSIS
In troubleshooting, the problem symptoms must be confirmed accurately and all preconceptions must be
cleared away in order to give an accurate judgement. To ascertain just what the problem symptoms are, it
is extremely important to ask the customer about the problem and the conditions at the time it occurred.
Important Point in the Problem Analysis:
The following 5 items are important points in the problem analysis. Past problems which are thought to be
unrelated and the repair history, etc. may also help in some cases, so as much information as possible should
be gathered and its relationship with the problem symptoms should be correctly ascertained for reference
in troubleshooting. A customer problem analysis table is provided in DI section for each system for your use.

DIAGNOSTIC TROUBLE CODE CHECK PROCEDURE
Diagnostic Trouble
Code Check (Make a
note of and then clear)Confirmation
of SymptomsDiagnostic Trouble
Code CheckProblem Condition
Diagnostic Trouble
Code DisplayProblem symptoms
existSame diagnostic
trouble code is
displayedProblem is still occurring in the diagnostic
circuit
Normal code is
displayedThe problem is still occurring in a place
other than in the diagnostic circuit
(The diagnostic trouble code displayed
first is either for a past problem or it is a
secondary problem)
No problem
symptoms existThe problem occurred in the diagnostic
circuit in the past
Normal Code DisplayProblem symptoms
existNormal code is
displayedThe problem is still occurring in a place
other than in the diagnostic circuit
No problem
symptoms existNormal code is
displayedThe problem occurred in a place other
than in the diagnostic circuit in the past
– INTRODUCTIONHOW TO TROUBLESHOOT ECU CONTROLLED
SYSTEMSIN–21
2. SYMPTOM CONFIRMATION AND DIAGNOSTIC TROUBLE CODE CHECK
The diagnostic system in the AVENSIS/ CORONA fulfills various functions. The first function is the Diagnos-
tic Trouble Code Check in which a malfunction in the signal circuits to the ECU is stored in code in the ECU
memory at the time of occurrence, to be output by the technician during troubleshooting. Another function
is the Input Signal Check which checks if the signals from various switches are sent to the ECU correctly.
By using these check functions, the problem areas can be narrowed down quickly and troubleshooting can
be performed effectively. Diagnostic functions are incorporated in the following systems in the AVENSIS/
CORONA.
SystemDiagnostic Trouble
Code CheckInput Signal Check
(Sensor Check)Other Diagnosis
Function
Supplemental Restraint System
In diagnostic trouble code check, it is very important to determine whether the problem indicated by the diag-
nostic trouble code is still occurring or occurred in the past but returned to normal at present. In addition,
it must be checked in the problem symptom check whether the malfunction indicated by the diagnostic
trouble code is directly related to the problem symptom or not. For this reason, the diagnostic trouble codes
should be checked before and after the symptom confirmation to determine the current conditions, as shown
in the table below. If this is not done, it may, depending on the case, result in unnecessary troubleshooting
for normally operating systems, thus making it more difficult to locate the problem, or in repairs not pertinent
to the problem. Therefore, always follow the procedure in correct order and perform the diagnostic trouble
code check.

Diagnostic trouble code check
Making a note of and clearing of the diagnostic trouble codes displayed
Symptom confirmation
No problem symptoms
exist Problem symptoms
exist
Simulation test using the symptom
simulation methods
 Normal code displayed
 Problem symptoms exist Normal code displayed
 No problem symptoms exist Diagnostic trouble code check
Troubleshooting of problem indicated
by diagnostic trouble code Diagnostic trouble code displayed
 Problem symptoms exist
System Normal Troubleshooting of each
problem symptom
If a diagnostic trouble code was
displayed in the initial diagnostic
trouble code check, it indicates
that the trouble may have occurred
in a wire harness or connector in
that circuit in the past. Therefore,
check the wire harness and con-
nectors (See page IN–29).
IN–22– INTRODUCTIONHOW TO TROUBLESHOOT ECU CONTROLLED
SYSTEMS
Taking into account the above points, a flow chart showing how to proceed with troubleshooting using the
diagnostic trouble code check is shown below. This flow chart shows how to utilize the diagnostic trouble
code check effectively, then by carefully checking the results, indicates how to proceed either to diagnostic
trouble code troubleshooting or to troubleshooting of problem symptoms.

V07268
VIBRATION METHOD: When vibration seems to be the major cause.
CONNECTORS
WIRE HARNESS
PARTS AND SENSOR1
Slightly shake the connector vertically and horizontally.
Slightly shake the wire harness vertically and horizontally.
The connector joint, fulcrum of the vibration, and body
through portion are the major areas to be checked thorough-
ly.
Apply slight vibration with a finger to the part of the sensor
considered to be the problem cause and check that the mal-
function occurs.Shake Slightly
Swing Slightly
Vibrate Slightly
HINT:
Applying strong vibration to relays may result in open relays.
– INTRODUCTIONHOW TO TROUBLESHOOT ECU CONTROLLED
SYSTEMSIN–23
3. SYMPTOM SIMULATION
The most difficult case in troubleshooting is when there are no problem symptoms occurring. In such cases,
a thorough customer problem analysis must be carried out, then simulate the same or similar conditions and
environment in which the problem occurred in the customer’s vehicle. No matter how much experience a
technician has, or how skilled he or she may be, if he or she proceeds to troubleshoot without confirming
the problem symptoms he or she will tend to overlook something important in the repair operation and make
a wrong guess somewhere, which will only lead to a standstill. For example, for a problem which only occurs
when the engine is cold, or for a problem which occurs due to vibration caused by the road during driving,
etc., the problem can never be determined so long as the symptoms are confirmed with the engine hot condi-
tion or the vehicle at a standstill. Since vibration, heat or water penetration (moisture) is likely cause for prob-
lem which is difficult to reproduce, the symptom simulation tests introduced here are effective measures in
that the external causes are applied to the vehicle in a stopped condition.
Important Points in the Symptom Simulation Test:
In the symptom simulation test, the problem symptoms should of course be confirmed, but the problem area
or parts must also be found out. To do this, narrow down the possible problem circuits according to the symp-
toms before starting this test and connect a tester beforehand. After that, carry out the symptom simulation
test, judging whether the circuit being tested is defective or normal and also confirming the problem symp-
toms at the same time. Refer to the problem symptoms table for each system to narrow down the possible
causes of the symptom.