1991 LEXUS SC300 service

ABBREVIATIONS USED IN THIS
MANUAL
ABS Anti±Lock Brake System J/B Junction Block
A/C Air Conditioner LED Light Emitting Diode
ALR Automatic Locking Retractor LH Left±Hand
APPROX. Approximation LHD Left±Hand Drive
A/T, ATM Automatic Transmission LLC Long Life Coolant (Year Around Coolant)
ATF Automatic Transmission Fluid Max. Maximum
BTDC Before Top Dead Center Min. Minimum
BVSV Bimetal Vacuum Switching Valve MP Multipurpose
CALIF. Vehicles Sold in California N Neutral
CB Circuit Breaker OD, O/D Overdrive
DOHC Double Over Head Cam O/S Oversize
DP Dash Pot P & BV Proportioning and Bypass Valve
ECT Electronic Controlled Transmission PCV Positive Crankcase Ventilation
ECU Electronic Controlled Unit PS Power Steering
EFI Electronic Fuel Injection RH Right±Hand
EGR Exhaust Gas Recirculation RL Rear Left
ELR Emergency Locking Retractor RR Rear Right
EPR Evaporator Pressure Regulator RR, Rr Rear
ESA Electronic Spark Advance SRS Supplemental Restraint System
EVAP Evaporative (Emission Control) SSM Special Service Materials
EX Exhaust (manifold, valve) SST Special Service Tools
Ex. Except STD Standard
FIPG Formed in Place Gasket SW Switch
FL Front Left TDC Top Dead Center
FL Fusible Link TDCL Total Diagnostic Communication Link
FPU Fuel Pressure Up Temp. Temperature
FR Front Right TRAC Traction Control System
FR, Fr Front TWC Three±Way Catalyst
HAC High Altitude Compensation VSV Vacuum Switching Valve
IG Ignition VTV Vacuum Transmitting Valve
IN Intake (manifold, valve) w/ With
INT Intermittent w/o Without
ISC Idle Speed Control
IN±34±
INTRODUCTION Abbreviations Used in This Manual
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HOW TO USE THIS MANUAL
INDEX
An INDEX is provided on the first page of each sec-
tion 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.
ALPHABETICAL INDEX
An ALPHABETICAL INDEX is also provided at the
end of this manual so that you can rapidly find the
item and page you are searching for.
GENERAL DESCRIPTION
At the beginning of each section, a General Descrip-
tion (Precautions) is given that pertains to all repair
operations contained in that section.
Read these precautions before starting any
repair task.
REPAIR PROCEDURES
Most repair operations begin with an overview il-
lustration. It identifies the components and shows
how the parts fit together.
Example:
PREPARATION
Preparation lists the SST (Special Service Tools), rec-
ommended tools, equipment, lubricant and SSM
(Special Service Materials) which should be prepared
before beginning the operation and explains the pur-
pose of each one.
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 trouble±
shooting are described on page IN±15. Be sure to
read this before performing troubleshooting.
IN±2
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INTRODUCTION How To Use This Manual
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5. Non±reusable parts(a) Always replace cotter pins, gaskets, O±rings and oilseals etc. with new ones.
(b) Non±reusable parts are indicated in the component
illustrations by the º º symbol.
6. Precoated parts Precoated parts are bolts and nuts, etc. that are coated with
a seal lock adhesive at the factory.
(a) If a precoated part is retightened, loosened or causedto move in any way, it must be recoated with the
specified adhesive.
(b) Recoating of precoated parts
(1) Clean off the old adhesive from the bolt, nut or threads.
(2) Dry with compressed air.
(3) Apply the specified seal lock adhesive to the bolt or nut threads.
(c) P re co a te d pa rts are in d ica te d in th e co m ponent
illustrations by the º
º symbol.
7. When necessary, use a sealer on gaskets to prevent leaks.
8. Carefully observe all specifications for bolt tightening
torques. Always use a torque 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 procedure. A list of SST and SSM
can be found in the preparation part at the front of each
section in this manual.
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.
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±33).
(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 a
vehicle raised on a jack alone, even for a small job that
can be finished quickly.
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INTRODUCTION General Repair InstructionsIN±5
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TOTAL DIAGNOSTIC
COMMUNICATION LINK (TDCL)
The TDCL is provided inside the cabin (located under the left side
instrument panel) as a connector exclusively for diagnosis of data
from the engine, ECT, ABS, A/C, Airbag and Cruise Control Sys-
tem to improve serviceability. The check connector inside the en-
gine compartment is used for engine adjustment.
Connecting the following terminals of the TDCL to terminal E1 se-
lects the diagnosis mode shown.
NOTICE: Never make a mistake with the terminal connection
position as this will cause a malfunction.
TerminalSystem
TE1Engine and ECT (Normal mode)
TE2 and TE1Engine and ECT (Test mode)
TcABS, A/C, Airbag, Traction Control and Cruise
Control System
TTECT
Refer to the respective system for the inspection method.
HINT: By connecting the TDCL up to a monitor specifically de-
signed for use with the TDCL, the diagnosis result for each system
can be read easily.
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INTRODUCTION Total Diagnostic Communication Link (TDCL)IN±7
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PRECAUTIONS FOR VEHICLES
EQUIPPED WITH SRS AIRBAG
The LEXUS SC400 is equipped with an SRS (Supplemental Re-
straint System) airbag.
Failure to carry out service operations in the correct sequence
could cause the airbag system to unexpectedly deploy during serv-
icing, possibly leading to a serious accident.
Further, if a mistake is made in servicing the airbag system, it is pos-
sible the airbag may fail to operate when required.
Before performing servicing (including removal or installation of
parts, inspection or replacement), be sure to read the following
items carefully, then follow the correct procedure described in this
manual.
Locations of Airbag Components
1. Malfunction symptoms of the airbag system are difficult to confirm,
so the diagnostic codes become the most important source of
information when troubleshooting.
When troubleshooting the airbag system, always inspect the diag-
nostic codes before disconnecting the battery. (See page
AB±25)
2. Work must be started after approx. 20 seconds or longer from the time the ignition switch is turned to the LOCK position and
the negative (±) terminal cable is disconnected from the
battery.
(The airbag system is equipped with a back±up power source
so that if work is started within 20 seconds of disconnecting
the negative (±) terminal cable of the battery, the airbag may be
deployed.)
IN±8±
INTRODUCTION Precautions for Vehicles Equipped with SRS Airbag
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HOW TO TROUBLESHOOT ECU CONTROLLED SYSTEMS
A large number of ECU controlled systems are used in the LEXUS SC400. In \
general, the ECU controlled sys-
tem is considered to be a very intricate system requiring a high level o\
f technical knowledge and expert skill to
troubleshoot. However, the fact is that if you proceed to inspect the circuits one by one, trou\
bleshooting 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 p\
roblem. This manual is de-
signed through emphasis of the above standpoint to help service technici\
ans perform accurate and effective
troubleshooting, and is compiled for the following major ECU controlled \
systems:
Repair ManualSystemPage
1. EngineTR±1
Vl1
2. Automatic TransmissionAT±33
Vol. 13. Anti±Lock BrakeBR±43
4. Traction ControlBR±139
5. Steering Column Electronic ControlSR±22
6. SRS AirbagAB±25
7. Power Seat ControlBE±265
Vl2
8. Door Lock ControlBE±347
Vol. 29. Theft DeterrentBE±381
10. Wireless Door Lock ControlBE±425
11. Cruise ControlBE±459
12. Air ConditionerAC±21
The troubleshooting procedure and how to make use of it are described on\
the following pages.
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INTRODUCTION How to Troubleshoot ECU Controlled SystemsIN±15
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[2] HEAT METHOD: When the problem seems to occur when the suspect area is heated.
Heat the component that is the likely cause of the malfunc-
tion with a hair dryer or similar object. Check to see if the
malfunction occurs.
NOTICE:
(1) Do not heat to more than 60°C (140 °F).
(Temperature limit that no damage is done to the
component).
(2) Do not apply heat directly to parts in the ECU.
[3] WATER SPRINKLING METHOD: When the malfunction seems to occur on a
rainy\
day or in a high±humidity condition.
Sprinkle w ater onto the vehicle and check to see if the mal-
function occurs.
NOTICE:
(1) Never sprinkle water directly into the engine compartment, but indirectly change the tempera-
ture and humidity by applying water spray onto
the radiator front surface.
(2) Never apply water directly onto the electronic components.
(Service hint)
If a vehicle is subject to water leakage, the leaked water
may contaminate the ECU. When testing a vehicle with a
water leakage problem, special caution must be used.
[4] OTHER: When the malfunction seems to occur when electrical load is excessive.
Turn on all electrical loads including the heater blower,
head lights, rear window defogger, etc. and check to see
if the malfunction occurs.
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INTRODUCTION TITLE±NAMEIN±21
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SERVICE SPECIFICATIONS
SERVICE DATA
Idle speedMagnetic clutch no engagedApprox. 700 rpm
Magnetic clutch engaged Approx. 700 rpm
Magnetic clutch clearance0.5 + 0.15 mm0.020 + 0.006 in.
TORQUE SPECIFICATIONS
Part tightenedN Vmkgf Vcmft Vlbf
Suction hose X Compressor2525018
Discharge hose X Compressor25250 18
Compressor X EngineBolt 49500 36
Nut 29300 22
Liquid tube X Receiver10100 7
Liquid tube X Condenser10100 7
Discharge tube X Condenser10100 7
Expansion valve X Evaporator5.455 48 in. Vlbf
Suction tube X A/C Unit10100 7
Liquid tube X A/C Unit10100 7
Equalizer tube X EPR25250 18
Pressure switch X Liquid tube101007
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AIR CONDITIONING SYSTEM Service SpecificationsAC±141
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