ABS system LEXUS SC300 1991 Service Repair Manual

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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12. Observe the following precautions to avoid damage to theparts:
(a) 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 electricity.).
(b) To pull apart electrical connectors, pull on the connectoritself, not the wires (See page BE±2).
(c) Be careful not to drop electrical components, such as sensors or relays. It they are dropped on a hard floor,
they should be replaced and not reused.
(d) When checking continuity at the wire connector, insert the tester probe carefully to prevent terminals from
bending.
(e) To disconnect vacuum hoses, pull on the end, not the middle of the hose.
(f) When steam cleaning an engine, protect the distributor,
coil and air filter from water.
(g) Ne ve r use an imp a ct wre n ch to re mo ve or in sta ll temperature switches or temperature sensors.
(h) When using a vacuum gauge, never force the hose onto
a connector 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 a job, double check that the vacuum hoses are properly connected. A label under the hood
shows the proper layout.
14. Installation of wheels The wheel assemblies are of the uni±directional type and
must be rotated only between the front and rear as illustrated.
Wheels are marked with turning direction indicators.
When installing the wheels, check the marks carefully and
install the wheel correctly.
15. Bleeding of traction control system When repairing the brake master cylinder or TRAC system,
bleed the air out of the TRAC system (See page BR±7).
CAUTION: Since the fluid is under high pressure, it could
spray out with great force, so be careful.
IN±6
±
INTRODUCTION General Repair Instructions
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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.
±
INTRODUCTION Total Diagnostic Communication Link (TDCL)IN±7
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EVAPORATOR
REMOVAL OF EVAPORATOR
1. DISCONNECT NEGATIVE (±) CABLE FROM BATTERY
2. RECOVER REFRIGERANT IN REFRIGERATION SYSTEMSee page AC±16
3. REMOVE ABS ACTUATOR
See page BR±48
4. REMOVE LIQUID TUBE AND SUCTION TUBE Remove two bolts and both tubes.
5. REMOVE EQUALIZER TUBE FROM EPR
Remove the bole and the tube.
NOTICE: Cap the open fittings immediately to keep mois-
ture out of the system.
6. REMOVE UNDER COVER GLOVE BOX AND SIDE AIR DUCT
7. DISCONNECT CONNECTORS AND REMOVE POWER STEERING RELAY BOX COOLING FAN COMPUTER AND
TRC COMPUTER
AC±122
±
AIR CONDITIONING SYSTEM Evaporator
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Description
The power source supplies power to each of the vehicle's electrical devices. It is composed of the battery, fuses
and relays, which are located centrally at relay block No. 2 and relay block No. 6 i\
n the engine compartment
and junction block No. 1 relay block No. 4 and relay block No. 5 in the \
cabin near the driver's feet.
Related systems for each Fuse
No.Part NameRelated Systems or Parts
1IGN
Charging System
AIR±BAG System1IGN
Engine
2ST
Starter
3WIPER
Wiper and Washer System
4HTR
Defogger System
A/C System
5ENGINE
Charging System
6RADIO NO. 2
Audio System
Power Mirror System

Cigarette Lighter
A/C System
7CIG
Combination Meter System
AIR±BAG System7CIG
Shift Lock System
Theft Deterrent System

TEL System
8STOP
Stop Light System
Cruise Control System
9TURN
Turn Signal and Hazard
Warning Light System
Cornnering Light System
10MIR HTR
Mirror Heater System
11PANEL
Illumination Light System
12ECU±B
Combination Meter System
AIR±BAG System

Combination Meter System
ECT System
13GAUGE
Back±Up Light
Transmission Indicator

Light Failare Sensor
ABS and TRAC

Power Seat System
Door Lock Control System

TEL System
Shift Lock System
14ECU±IG
Radiator Fan
Auto Antenna

Electric Tension Reducer System
Power Steering

Auto±Tilt away Steering
Cruise Control System
15TAIL
Taillight System
Side Marker15TAIL
Clearance Light
16DOOR
Power Seat System
Luggage Door Opener16DOOR
Door Lock Control System
Fuel Lid Opener System
17IG SWUpstream of ECU±IG, ENGINE, WIP, HTR, TURN, GAUGE, and ST Fuse
18PWR
Power Window System
Sliding Roof System
19ABS NO. 1
ABS and TRAC
20AM1Upstream of MIR HTR, TAIL, PANEL, STOP, ECUA±B, DOOR and PWR Fuse
21ALTUpstream of DEF, HTR, AM1, and ABS No. 1 Fuse
BE±18±
BODY ELECTRICAL SYSTEM Power Source
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No.Part NameRelated Systems or Parts
22MAIN
Upstream of ALT±S and EFI Fuse
23AM2
Charging System
Engine23AM2
AIR±BAG System
24ABS NO. 2
ABS and TRAC
25INJ
Charging System
Engine25INJ
AIR±BAG System
26DEF
Defogger System

Power Seat System
Sliding Roof System

A/C System
Liquid Crystal Inner Mirror System
27DOME
Combination Meter System
Interior Light System27DOME
ABS and TRAC
Wireless Door Lock Control System

Cruise Control System
Auto±Tilt away Steering

Theft Deterrent System
28EFI
Engine
29HAZ HORN
Turn Signal and Hazard Warning Light System29HAZ±HORN
Horn System
30RADIO NO. 1
Audio System
31TEL
TEL System
32ALT±S
Charging System
33TRAC
ABS and TRAC
34HEAD (RH±LWR)
Headlight System
35HEAD (LH±LWR)
Headlight System
36HEAD (RH±UPR)
Headlight System
37HEAD (LH±UPR)
Headlight System
38HTR
Blow Motor
±
BODY ELECTRICAL SYSTEM Power SourceBE±19
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2. INSPECT RELAY CIRCUITRemove the relay from the junction block and inspect the
connector on junction block side as shown.
RelayCheck forTester connectionConditionSpecified value
TAILVoltage(1)±GroundConstantBattery voltage
(4)±Ground
P/W MAIN(6)±Ground
If the circuit is not as specified, refer to BE±15 wiring diagram
and inspect the circuits connected to other parts.
INSPECTION OF RELAY BLOCK NO. 2
1. INSPECT FUSE CIRCUIT Remove the fuse from the relay block and inspect the con-
nector on relay block side as shown.
FuseCheck forTester ConnectionConditionSpecified value
ABS NO. 1Voltage2±GroundConstantBattery voltage
AM14±Ground
ALT5±Ground
MAIN7±Ground
AM29±Ground
ABS NO. 211±Ground
INT13±Ground
±
BODY ELECTRICAL SYSTEM Power SourceBE±21
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If the circuit is not as specified, refer to BE±15 wiring diagram
and inspect the circuits connected to other parts.
INSPECTION OF RELAY BLOCK NO. 6
(ABS and TRAC Relay Block)
INSPECT RELAY CIRCUIT
Remove the relay from the relay block and inspect the con-
nector on junction block side as shown.
RelayCheck forTester connectionConditionSpecified value
TRAC SOLVoltage(1)±GroundConstantBattery voltage
TRAC MTR(7)±Ground
ABS SOL(11)±Ground
ABS MIR(17)±Ground
If the circuit is not as specified, refer to BE±15 wiring diagram
and inspect circuits connected to other parts.
BE±24
±
BODY ELECTRICAL SYSTEM Power Source
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(GLOVE BOX LIGHT SWITCH)
REMOVAL AND INSTALLATION OF
GLOVE BOX LIGHT SWITCH
1. REMOVE GLOVE BOX LIGHT SWITCH(a) Remove glove compartment.
(See page BO±112)
(b) Release two tabs and remove switch.
2. INSTALL GLOVE BOX LIGHT SWITCH For installation, follow the removal procedure in reverse.
INSPECTION OF GLOVE BOX LIGHT
SWITCH
INSPECT GLOVE BOX LIGHT SWITCH
(Continuity)
Inspect the switch continuity between terminals.
If continuity is not as specified, replace the switch.
(Switch Circuit)
Disconnect the connector from the switch and inspect the
connector on the wire harness side as shown.
Check forTester connectionConditionSpecified value
Continuity2±GroundConstantContinuity
Voltage1±GroundLight control switch posi-OFFNo voltageVoltage1±Groundg
tionTAIL or HEADBattery positive voltage
If the circuit is not as specified, refer to BE±76 wiring diagram
and inspect the circuits connected to other parts.
(INTEGRATION RELAY)
(See page BE±49 )
(TAILLIGHT CONTROL RELAY)
(See page BE±57 )
BE±74
±
BODY ELECTRICAL SYSTEM Lighting System
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(Front Personal Light Switch)
REMOVAL AND INSTALLATION OF
FRONT PERSONAL LIGHT
1. REMOVE FRONT PERSONAL LIGHT(a) Release eight tabs and remove the lens.
(b) Remove three screws and separate front personal light.
(c) Disconnect connector and remove front personal light.
2. INSTALL FRONT PERSONAL LIGHT For installation, follow the removal procedure in reverse.
INSPECTION OF FRONT PERSONAL
LIGHT
INSPECT FRONT PERSONAL LIGHT SWITCH(Continuity)
Inspect the light switch continuity between terminals.
If continuity is not as specified, replace the light assembly or
bulb.
(Switch Circuit)
Disconnect the connector from the switch and inspect the
connector on the wire harness side as shown.
Check forTester connectionConditionSpecified value
Voltage3±GroundConstantBattery voltage
Continuity1±GroundConstantContinuity
If circuit is not as specified, inspect power source or wire
harness.
BE±80
±
BODY ELECTRICAL SYSTEM Lighting System
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