Toyota VZN150 series User manual

•
•
FOREWORD
This manual contains maintenance and repair procedures for
the 1996 TOYOTA TACOMA.
Applicable models:
RZN140,
150, 161, 171 series
VZN
150, 160, 170 series
The manual is divided
into 21 sections with a thumb index for
each section at the edge of the pages.
Please note that the publications below have also been
prepared
as relevant service manuals for the components and
systems in this vehicle.
Manual Name Pub. No.
•
A43D Automatic Transmission Repair
RM387U
Manual (Nov. 1993)
• A340E, A340F, A340H Automatic
RM391 U
Transmission Repair Manual (Nov.
1993)
• A340F, A343F Automatic Transmission
RM479U
Repair Manual (Sep. 1995)
• 1996 Toyota Tacoma Electrical Wiring
EWD246U
Diagram
•
1996 Model TOYOTA New Car Features NCF120U
All
information in this manual is based on the latest product in-
formation at the time of publication. However, specifications
and procedures are subject
to change without notice.
TOYOTA MOTOR CORPORATION
©2000 TOYOTA MOTOR CORPORATION
All rights reserved. This book may not be repro-
duced or copied, in whole or in part, without the
written permission of Toyota Motor Corporation.
First
Printing: Jul. 14, 1995 01-950714-00
Sixth Printing: Feb. 28, 2000 06-000228-01-2

CAUTION
This manual does not include all the necessary items about repair and service. this manual is made
for the purpose of the use for the persons who have special techniques and certifications. In the
cases that non-specialized or uncertifiedtechnicians perform repair or service only using this manu-
al or without proper equipment or tool, that may cause severe injury to you or other people around
and also cause damage to your customer's vehicle.
In order to prevent dangerous operation and damages to your customer's vehicle, be sure to follow
the instruction shown below.
• Must read this manual thoroughly. It is especially important to have good understanding all the
contents written in the PRECAUTION of "IN" section.
•
• The service method written in this manual is very effective to perform repair and service. When
performing the operations following the procedures using this manual, be sure to use tools spe-
cified and recommended. If using non-specified or recommended tools and service method,
be sure to confirm safety of the technicians and any possibility of causing personal injury or
damage to the customer's vehicle before starting the operation.
•
If part replacement is necessary, must replace the part with the same partnumber or equivalent
part. Do not replace it with inferior quality.
•It is important to note that this manual contains various "Cautions" and "Notices" that must be •
carefully
observed in order to reduce the risk of personal injury during service or repair, or the
possibility that improperservice or repair may damage the vehicle or render it unsafe. It is also
important to understand that these "Cautions" and "Notices" are not exhaustive, because it is
important to warn of all the possible hazardous consequences that might result from failure to
follow these instructions.
•

•
•
•
INTRODUCTION
MAINTENANCE
2RZ-FE, 3RZ-FE ENGINE
5VZ-FE ENGINE
IGNITION SYSTEM
STARTING SYSTEM
CHARGING SYSTEM
CLUTCH
W59 MANUAL TRANSMISSION
R150, R150F
MANUAL TRANSMISSION
A43D AUTOMATIC TRANSMISSION
A340E, A340F AUTOMATIC TRANSMISSION
TRANSFER
PROPELLER SHAFT
SUSPENSION AND AXLE
BRAKE SYSTEM
STEERING
SUPPLEMENTAL RESTRAINT SYSTEM
BODY ELECTRICAL SYSTEM
BODY
AIR CONDITIONING SYSTEM

J .......... ----------.
•
•
•

•
•
•
IN-1
INTRODUCTION
HOW TO USE THIS MANUAL IN -2
IDENTIFICATION INFORMATION IN- 4
GENERAL REPAIR INSTRUCTIONS IN- 5
PRECAUTION
IN -8
HOW TO TROUBLESHOOT ECU
CONTROLLED SYSTEM IN- 13
VEHICLE LIFT AND SUPPORT
LOCATIONS
IN- 30
ABBREVIATIONS USED IN THIS
MANUAL IN - 31
GLOSSARY OF SAE AND TOYOTA
TERMS
IN- 33
STANDARD BOLT TORQUE
SPECIFICATIONS
IN- 36

GENERAL DESCRIPTION
INOlO-01
HOW TO USE THIS MANUAL
INDEX •
INOZE-01
INTRODUCTION -HOW TO USE THIS MANUAL
An INDEX is provided on the first page of each section to guide you to the item to be repaired.
To assist you in finding your
way through the manual, the Section Title and major heading are
given at the
top of every page.
IN-2
At the beginning of each section, ageneral Description is given that pertains to all repair
operations contained
in that section.
Read these precautions before starting any repair task.
_-00
TROUBLESHOOTING
TROUBLESHOOTING tables are included for each system to help you diagnose the problem and
find the cause. The fundamentals
of how to proceed with troubleshooting are described on page
IN -13. Be sure to read this before performing troubleshooting.
tNOaJ-01
PREPARATION
Preparation lists the SST (Special Service Tools), recommended tools, equipment, lubricant and
SSM (Special Service Materials)
which should be prepared before beginning the operation and
explains the purpose
of each one.
REPAIR PROCEDURES
Most repair operations.begin with an overview illustration. It identifies the components and •
shows
how the parts fit together.
Example:
•
Nl1306
Clevis Pin
.G .....lClip
t) Cl,v',
ILock Nut
Snap Ring
Washer
Push Rod
Piston
-~
___ -"!U
~§~~----Reservoir Tank
Cylinder
®-------Filler Cap
~ Float
•Non-reusable part

INTRODUCTION -HOW TO USE THIS MANUAL
IN-3
•
•
The procedures are presented in a step-by-step format:
•The illustration shows
what to do and where to do it .
•The task heading tells
what to do.
•The detailed
text tells how to perform the task and gives other information such as
specifications and warnings.
Example:
This
format provides the experienced technician with aFAST TRACK to the information needed.
The upper case task heading can
be read at aglance when necessary, and the text below it
provides detailed information. Important specifications and warnings always stand out in bold
type.
IN02L-01
REFERENCES
References have been kept to aminimum. However, when they are required you are given the
page
to refer to.
IN02.M-OI
SPECIFICATIONS
Specifications are presented in bold type throughout the text where needed. You never have to
leave the procedure to look up your specifications. They are also found at the end of each section,
for quick reference.

SI UNIT
The UNITS given in this manual are primarily expressed according to the SI UNIT (International
System
of Unit). and alternately expressed in the metric system and in the English System.
Example:
Torque:
30 N·m (310 kgf·cm. 22 ft.lbf)
III02N-01
INOOI-OO
HIOII-01
The vehicle identification number is stamped on the •
vehicle identification number plate and certification
label.
A. Vehicle Identification Number Plate
B. Certification Label
The engine serial number is stamped on the engine
block
as shown.
IDENTIFICATION INFORMATION
VEHICLE IDENTIFICATION NUMBER
ENGINE SERIAL NUMBER
INTRODUCTION -IDENTIFICATION INFORMATION
IWOI'-OI
CAUTIONS are presented in bold type. and indicate there is apossibility of injury to you or •
other people.
NOTICES are also presented in bold type. and indicate the possibility
of damage to the
components being repaired.
HINTS are separated from the
text but do not appear in bold. They provide additional
information
to help you perform the repair efficiently.
•
•
•
2RZ-FE, 3RZ-FE Engi-ne :
CAUTIONS, NOTICES, HINTS:
IN-4
5VZ-FE
Engine:
•
N14492

INTRODUCTION -GENERAL REPAIR INSTRUCTIONS
•
•
•IN0036 Seal Lock Adhesive
FI1066
Zll554
IN-5
GENERAL REPAIR INSTRUCTIONS
IN059-01
1. Use fender, seat and floor covers to keep the vehicle
clean and prevent damage.
2. During disassembly, keep parts in the appropriate
order
to facilitate reassembly.
3. Observe the following:
(a) Before performing electrical work, disconnect
the negative
(-) terminal cable from the battery.
(b) If it is necessary to disconnect the battery for
inspection or repair, always disconnect the nega-
tive
(-) terminal cable which is grounded to the
vehicle body.
(c) To prevent damage to the battery terminal,
loosen the cable
nut and raise the cable straight
up without twisting or prying it.
(d) Clean the battery terminals and cable ends with a
clean shop rag. Do
not scrape them with afile or
other abrasive objects.
(e) Install the cable ends to the battery terminals
with the nut loose, and tighten the nut after
installation. Do not use ahammer to tap the cable
ends
onto the terminals.
(f)
Be sure the cover for the positive (+) terminal is
properly in place.
4. Check hose and wiring connectors
to make sure that
they are secure and correct.
5. Non-reusable parts
(a) Always replace cotter pins, gaskets, O-rings and
oil seals etc.
with new ones.
(b) Non-reusable parts are indicated in the compo-
nent illustrations by the
••• symbol.
6. Precoated parts
Precoated parts are bolts and nuts, etc.
that are
coated
with aseal lock adhesive at the factory.
(a) If a precoated part is retightened, loosened or
caused to move in any way, it must be recoated
with the specified adhesive.

IN-6 INTRODUCTION -GENERAL
REPAIR INSTRUCTIONS
(b) 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.
(c) Precoated parts are indicated in the component
illustrations
by the -*- symbol.
7. When necessary, use asealer on gaskets to prevent
leaks.
8. Carefully observe all specifications
for bolt tightening
torques. Always use atorque wrench.
9. Use
of special service tools (SST) and special service
materials (SSM) may
be required, depending on the
nature
of the repair. Be sure to use SST and SSM
where specified and
follow the proper work proce-
dure. Alist
of SST and SSM can be found in the
preparation part
at the front of each section in this
manual.
Medium Current Fuse and High Current Fuse
Equal Amperage Rating
~_-'i ~
~ ~
~
BE1367
10. When replacing fuses, be sure the new fuse has the
correct amperage rating.
DO NOT exceed the rating or
use one with a lower rating. •
Illustration Symbol Part Name
Abbreviation
~
~
FUSE FUSE
0,<>;
BE5694 IN0366
~
~
MEDIUM CURRENT FUSE M-FUSE
BE6696 IN0366
~
~
HIGH CURRENT FUSE H-FUSE
BE6696 IN0367
/
~
FUSIBLE LINK
FL
BE6697 IN0367
~
-+=4- .. .-
CIRCUIT BREAKER
CB
BE5598
VWJ76
•

11. Care must be taken when jacking up and supporting
the vehicle.
Be sure to lift and support the vehicle at
the proper locations (See page IN-30).
(a) If the vehicle is to be jacked up only at the front
or rear end. be sure to block the wheels at the
opposite end in order
to ensure safety.
(b) After the vehicle is jacked up. be sure to support
it on stands. It is extremely dangerous to do any
work on avehicle raised on a jack alone. even for
asmall job that can be finished quickly.
12. Observe the following precautions
to avoid damage to
the following parts:
(a) Do not open the cover or case of the ECU. ECM.
PCM
or TCM unless absolutely necessary. (If the
IC terminals are touched. the IC may be destr-
oyed by static electricity.)
•INTRODUCTION -GENERAL
REPAIR INSTRUCTIONS IN-7
•
•
WRONG CORRECT
IN0253
WRONG CORRECT
IN0252
Example
INOOO2
(b) To disconnect vacuum hoses. pull on the end. not
the middle of the hose.
(c) To pull apart electrical connectors. pull on the
connector itself.
not the wires.
(d) 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.
(e) When steam cleaning an engine. protect the dis-
tributor. air filter. and VCV from water.
(f) Never use an impact wrench
to remove or install
temperature switches
or temperature sensors.
(g) When checking continuity at the wire connector.
insert the tester probe carefully
to prevent termi-
nals from bending.
(h) When using avacuum gauge. never force the
hose onto aconnector that is too large. Use a
step-down adapter instead. Once the hose has
been stretched.
it may leak.
13. Tag hoses before disconnecting them:
(a) When disconnecting vacuum hoses. use tags to
identify how they should be reconnected.
(b) After completing ajob. double check that the
vacuum hoses are properly connected. Alabel
under the hood shows the proper layout.
14. Unless otherwise stated. all resistance is measured
at
an ambient temperature of 20°C (68°F). Because the
resistance may
be outside specifications if measured
at high temperatures immediately after the vehicle
has been running. measurements should be made
when the engine has cooled down.

IN-8 INTRODUCTION -PRECAUTION
PRECAUTION INOIA.-01
FOR VEHICLES EQUIPPED WITH AIRBAG
The 1996 TOYOTA TACOMA is equipped with an SRS
(Supplemental Restraint System), such as the driver
airbag.
Failure
to carry out service operations in the correct
sequence could cause the supplemental restraint
system
to unexpectedly deploy during servicing, pos-
sibly leading
to aserious accident.
Further,
if amistake is made in servicing the supple-
mental restraint system,
it is possible the SRS may fail
to operate when required. Before servicing (including
removal
or installation of parts, inspection or replace-
ment), be sure
to read the following items carefully,
then
follow the correct procedure described in this
manual.
•
804111
1.
2.
Malfunction symptoms of the supplemental restraint
system are
difficult to confirm, so the diagnostic trou-
ble codes become the most important source of infor-
mation when troubleshooting.
When troubleshooting
the supplemental restraint system, always inspect the
diagnostic trouble codes before disconnecting the
battery
(See page RS - 2).
Work must be started after 90 seconds from the
time the ignition switch is turned to the -LOCK-
position and the negative (-) terminal cable is dis-
connected
from the battery.
(The supplemental restraint system is equipped
with aback- up power source so that if work is
started within 90 seconds of disconnecting the neg-
ative (-) terminal cable from the battery. the SRS
may deploy.)
When the negative (-) terminal cable is disconnected
from the battery, memory
of the clock and audio
systems will be cancelled. So before starting
work,
make arecord of the contents memorized by the audio
memory system. When
work is finished, reset the
audio systems
as before and adjust the clock.
This vehicle has
power tilt and power telescopic steer-
ing,
power seat, power outside rear view mirror and
power shoulder belt anchorage, which are all equi-
pped
with memory function, it is not possible to make
arecord
of the memory contents.
•

So when the work is finished, therefore it will be
necessary
to explain this fact to the customer, and ask
the customer to adjust the features and reset the
memory.
To avoid erasing the memory of each memory system.
never use aback-
up power supply from outside the
vehicle.
3. Even in cases
of a minor collision where the SRS does
not deploy, the steering wheel pad should be in-
spected (See page
RS -8).
4. Never use SRS parts from another vehicle. When
replacing parts, replace them with new parts.
5. Before repairs, remove the airbag sensor if shocks are
likely
to be applied to the sensor during repairs.
6. Never disassemble and repair
the airbag sensor as-
sembly, steering
wheel pad in order to reuse it.
7. If the airbag sensor assembly, steering wheel pad
have been dropped,
or if there are cracks. dents or
other defects in the case, bracket or connector, re-
place
them with new ones.
8. Do not expose the airbag sensor assembly, steering
wheel pad
directly to hot air or flames.
9. Use a volt/ohmmeter with high impedance (10 kQ/V
minimum) for troubleshooting of the electrical circuit.
10. Information labels are attached to the periphery of the
SRS components. Follow the instructions on the
notices.
11.
After work on the supplemental restraint system is
completed, check
the SRS warning light (See page RS
-26).
•
•
INTRODUCTION -PRECAUTION
IN-9
•Red Mark
Spiral Cable (in Combination Switch)
The steering wheel must be fitted correctly to the
steering column with the spiral cable at the neutral
position,
otherwise cable disconnection and other tro-
ubles may result. Refer to SR-16 of this manual
concerning
correct steering wheel installation.
Rl1910

IN·10
INTRODUCTION -PRECAUTION
Steering Wheel Pad (with Airbag)
Example:
N01560
1.
2.
3.
4.
5.
6.
When removing the steering wheel pad or handling
a
new steering wheel pad, it should be placed with
the pad top sUJ:face facing up.
In this case, the twin -lock type connector lock lever
should be in
the locked state and care should be taken
to place it so the connector will not be damaged. In
addition do
not store asteering wheel pad on top of
another one. Storing the pad with its metallic surface
up may lead
to aserious accident if the airbag inflates
for some reason.
Never measure the resistance of the airbag squib.
(This
may cause the airbag to deploy, which is very
dangerous.)
Grease should
not be applied to the steering wheel
pad and the pad should
not be cleaned with deter-
gents
of any kind.
Store the steering wheel pad where the ambient tem-
perature remains
below 93° C(200° F), without high
humidity and away from electrical noise.
When using electric welding.
first disconnect the
airbag connector (yellow color and 2pins) under the
steering column near the combination
switch connec-
tor before starting work.
When disposing of a vehicle or the steering wheel
pad alone, the airbag s~ould be deployed using an
SST
before disposal (See page RS-11).
Carry out the operation in a safe place away from
electrical noise.
Wrong
X
Zl3<J53
.~
ZI3950
.~

INTRODUCTION -PRECAUTION IN-11
•
•
•
Airbag Sensor Assembly
1. Never reuse the airbag sensor assembly involved in> a
collision when the
SRS has deployed.
2. The connectors to the airbag sensor assembly should
be connected or disconnected with the sensor mount-
ed on the floor. If the connectors are connected or
disconnected while the airbag sensor assembly is not
mounted to the floor, it could cause undesired ignition
of the supplemental restraint system.
3. Work must be started after 90 seconds from the time
the ignition
switch is turned to the "LOCK" position
and the negative
(-) terminal cable is disconnected
from the battery, even
if only loosening the set bolts
of the airbag sensor assembly.
Wire Harness and Connector
The SRS wire harness is integrated with the cowl wire
harness assembly and
floor wire harness assembly.
The wires
for the SRS wire harness are encased in a
yellow corrugated tube. All the connectors for the
system are also astandard yellow color. If the SRS
wire harness becomes disconnected or the connector
becomes broken due
to an accident, etc., repair or
replace it as shown on page RS-20.
INOOI-OI
FOR VEHICLES EQUIPPED WITH A CAT AL VTIC CONVERTER
CAUTION: If large amounts of unburned gasoline flow into the converter, it may overheat and create
a fire hazard. To prevent this, observe the following precautions and explain them to your customer.
1. Use only unleaded gasoline.
2.
Avoid prolonged idling.
Avoid running the engine at idle speed for more than 20 minutes.
3. Avoid spark jump test.
(a) Perform spark jump test only when absolutely necessary. Perform this test as rapidly as possible.
(b) While testing, never race the engine.
4.
Avoid prolonged engine compression measurement.
Engine compression tests
must be done as rapidly as possible.
5. 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.
6.
Avoid coasting with ignition turned off and prolonged braking.
7. Do not dispose of used catalyst along with parts contaminated with gasoline or oil•

IF VEHICLE IS EQUIPPED WITH MOBILE COMMUNICATION SYSTEM
IN-12
INTRODUCTION -PRECAUTION
INOIII-OD
For vehicles with mobile communication systems such as two-way radios and cellular tele- •
phones, observe the
following precautions.
(1) Install the antenna
as far as possible away from the ECM, ECU and sensors of the vehicle's
electronic system.
(2) Install
the antenna feeder at least 20 cm (7.87 in.) away from the ECM, ECU and sensors of the
vehicle's electronics systems. For details
about ECM, ECU and sensors locations, refer to the
section on the applicable component.
(3) 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.
(4) Confirm
that the antenna and feeder are correctly adjusted.
(5) Do
not install powerful mobile communications system.
•
•

INTRODUCTION - HOW TO TROUBLESHOOT ECU CONTROLLED SYSTEMS
IN-13
•
•
HOW TO TROUBLESHOOT ECU CONTROLLED SYSTEMS
Alarge number of ECU controlled systems are used in the TACOMA. In general, the ECU controlled system
is considered to be avery intricate system requiring ahigh level of technical knowledge and expert skill to
troubleshoot. However, the fact is that if you proceed to inspect the circuits one by one, troubleshooting of
these systems is not complex. If you have adequate understanding of the system and abasic 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 systems:
System Page
2RZ-FE, 3RZ-FE Engine EG-184
1. 5VZ-FE Engine EG-192
2.
A340E, A340F Automatic Transmission AT-32
3. Anti-Lock Brake BR-43
4. Supplemental Restraint System RS-23
5.
Cruise Control BE-79
The troubleshooting procedure and how to make use of it are described on the following pages.

HOW TO PROCEED WITH TROUBLESHOOTING
IN-14
INTRODUCTION - HOW TO TROUBLESHOOT ECU CONTROLLED SYSTEMS
Carry out troubleshooting in accordance with the procedure on the following page. Here, only the basic proce- •
dure is
shown. Details are provided in each section, showing the most effective methods for each circuit.
Confirm the troubleshooting procedures first for the relevant circuit before beginning troubleshooting of that
circuit.
[[] Matrix Chart of Problem
Symptoms
•
rn[]]rn
Check the results obtained in Step []] , then con-
firm the inspection procedure for the system or
the part which should be checked using the
diagnostic trouble code chart or the matrix chart
of problem symptoms.
IT]
Ask the customer about the conditions and the
environment when the problem occurred.
rnrn
----....,
Confirm the symptoms and the problem condi-
tions, and check the diagnostic trouble codes.
(When the problem symptoms do not appear dur-
ing
confirmation, use the symptom simulation
method described later on.)
mSimulation
Customer Problem
Analysis
JJ
(Vehicle Brought to workshoP)
ISymptom Conf;rmat;on t. []]
and Diagnostic
Trouble Code Check
<;:J/ Sympto
/ Diagnostic Trouble Code Chart /
IT]
rn
Circuit Inspection or Parts
Inspection
D
IIJ/
Repair 7
D
00/
Confirmation Test
7
D
(
End
)
Check and repair the affected system or part in
accordance
with the instructions in Step []] .
After completing repairs, confirm that the problem
has been eliminated.
(If the problem
is not reproduced, perform the con-
firmation test under the same conditions and in
the same environment as when it occurred for
the first time.)
•

INTRODUCTION - HOW TO TROUBLESHOOT ECU CONTROLLED SYSTEMS
IN-15
•
•
•
[]J 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 Points 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 the troubleshooting section for each
system for your use.
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) Engine control system check sheet.
CUSTOMER PROBLEM ANALYSIS CHECK SHEET
IENGINE CONTROL System Check Sheet I
Inspector's
Name
Customer's Model and model
name year
Driver's name Frame no.
Date vehicle Engine model
brought in
license no. Odometer reading km
miles
oEngine does
[[ Engine does not crank [[ No initial combustion [[ No complete combustion
not Start
o Difficult to
[I Engine cranks slowly
..
Start
[I Other
E
[I Incorrect first idle
[[ Idling rpm is abnormal I[ [High
[[ Low (rpm)]
0oPoor Idling
Q.
II Rough idling
[[ Other
E
>
[] Poor [[ Hesitation [i Back fire [I Muffler explosion (after-fire) Surging
(I)
EDriveability
[[ Knocking
[[ Other
~
nSoon after starting I] After accelerator pedal depressed
enEngine Stall
[] After accelerator pedal released I] During A/C operation
0-
[[ Shifting from N to D [[ Other
[] Others
Dates Problem
Occurred
Problem Frequency
[I Constant [[ Sometimes (times per
day/month)
[Once only
[[ Other
Weather rIFine
[I Cloudy II Rainy [] Snowy
[] Various/Other
--
....
r
~ ....
~
[] Hot
:i Warm [I Cool IJ Cold
(approx._oF I_DC) -=
~
,U
Highway i [ Suburbs [I Inner City
[I UPhil'./'
Rough road
[I Other
~
[I Warming up [I After warming up
of
~terstarting ~
nstant speed [ [ Ac

IN-16
INTRODUCTION - HOW TO TROUBLESHOOT ECU CONTROLLED SYSTEMS
[I] SYMPTOM CONFIRMATION AND DIAGNOSTIC TROUBLE CODE CHECK
The diagnostic system in the TACOMA fulfills various functions. The first function is the Diagnostic Trouble
Code Check in which amalfunction 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. The air condi-
tioner system has an Actuator Check function whereby the ECU automatically operates the actuators of the
damper and blowermotor, etc. to check the operation. 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 TACOMA.
System Diagnostic Trouble
Input Signal Check Other Diagnosis
Code Check (Sensor Check) Function
2RZ-FE, 3RZ-FE o (with Check Mode) 0Diagnostic Test Mode
Engine 5VZ-FE o
(with Check Mode) 0Diagnostic Test Mode
Automatic Transmission o
(with Check Mode) 0Diagnostic Test Mode
Supplemental Restraint System 0 0
In diagnostic trouble code check, it is very important to determine whether the problem indicated by the
diagnostic trouble code is still occurring or occurred in the past but returned to normal at present. In addi-
tion, 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 condi-
tions, 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 TROUaLE CODE CHECK PROCEDURE
Diagnostic Trouble
Confirmation of
Code Check (Make aDiagnosticTrouble Problem Condition
note of and then
Symptoms Code Check
clear)
Diagnostic Trouble Problem
symptoms
Same diagnostic Problem is still occurring in
the diagnostic
Code Display
exist
trouble code is circuit.
displayed
c::
~
Normal code is The problem is still occurring in aplace other
displayed than in
the diagnostic circuit.
(The diagnostic trouble code displayed
first is
either for apast problem or it is asecondary
problem.)
c::
~o problem The problem occurred in
the diagnostic circuit
symptoms exist
in the past.
Normal Code Display c:
~r~blem symptoms
Normal code is The problem is still occurring in aplace
other
eXist displayed than in
the diagnostic circuit.
c::
~o problem Normal code is The problem occurred in aplace
other than in
symptoms exist displayed the diagnostic circuit in the past. •