1991 LEXUS SC400 charging

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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OKNG
NGOK
OKNG
INSPECTION PROCEDURE
1Check battery positive voltage.
Voltage: 10 ± 14 VCOK
Check and repair the charging system.
2Check voltage between terminals IG and GND of TRAC ECU connector.
C
OK
P1. Remove TRAC ECU with connectors still con-nected.
2. Turn ignition switch on.
Measure voltage between terminals IG and GND of
TRAC ECU connector.
Voltage: 10 ± 14 V
Check and replace TRAC ECU.
3Check continuity between terminals GND of TRAC ECU connector and body gr\
ound.
C
OK
Measure resistance between terminal GND or TRAC
ECU connector and body ground.
Resistance: 1
or less
Repair or replace harness or connector.
±
BRAKE SYSTEM TRACTION CONTROL SYSTEM (TRAC)BR±193
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OKNG
NGOK
INSPECTION PROCEDURE
1Check battery positive voltage.
Voltage: 10 ± 14 VOK
Check and repair the charging system.
2Check voltage between terminals IG1 and GND or ABS (& TRAC) ECU connec\
tor.
C
OK
PRemove ABS (& TRAC) ECU with connectors still con-
nected.
1. Turn ignition switch on.
2. Measure voltage between terminals IG1 and GNDof ABS (& TRAC) ECU connector.\
Voltage: 10 ± 14 V
Check and replace ABS (& TRAC) ECU.
±
BRAKE SYSTEM ANTI±LOCK BRAKE SYSTEM (ABS)BR±123
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SERVICE SPECIFICATIONS
SERVICE DATA
BatterySpecific gravity1.27±1.29
(when fully charged at 205C (68 5F))
AlternatorRated output12 V±100 A
Rotor coil resistance2.8±3.0

Slip ring diameterSTD 14.2±14.4 mm0.559±0567 in.
Limit 12.8 mm0.504 in.
Brush exposed lengthSTD 10.5 mm0.413 in.
Limit 1.5 mm0.059 in.
AlternatorRegulating voltageat 255C (77 5F)13.9±15.1 V
regulatorat 115 5C (239 5F)13.5±14.3 V
TORQUE SPECIFICATIONS
Part tightenedN Vmkgf Vcmft Vlbf
Alternator pulley X Rotor11 01,12581
Alternator X Alternator bracket37380 27
Alternator X Cylinder block3738027
±
CHARGING SYSTEM Service SpecificationsCH±21
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CHARGING SYSTEM
CHARGING SYSTEM
CH±1
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DESCRIPTION
The alternator is a small, high±rpm, high±performance type with an IC\
regulator incorporated. The IC regula-
tor uses integrated circuits and controls the voltage produced by the alter\
nator.
PRECAUTIONS
1. Check that the battery cables are connected to the correct terminals.
2. Disconnect the battery cables when the battery is given a quick charge.
3. Do not perform tests with a high voltage insulation resistance tester.
4. Never disconnect the battery when the engine is running. CH±2
±
CHARGING SYSTEM Description, Precautions
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DESCRIPTION
The alternator is a small, high±rpm, high±performance type with an\
IC regulator incorporated. The IC regula-
tor uses integrated circuits and controls the voltage produced by the alter\
nator.
PRECAUTIONS
1. Check that the battery cables are connected to the correct terminals.
2. Disconnect the battery cables when the battery is given a quick charge.
3. Do not perform tests with a high voltage insulation resistance tester.
4. Never disconnect the battery when the engine is running. CH±2
±
CHARGING SYSTEM Description, Precautions
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SYSTEM CIRCUIT
OPERATION
When the ignition switch is turned ON, current from the battery flows from t\
erminal L of the alternator through
the IC regulator to terminal E, causing the discharge warning light to ligh\
t up. Then when the engine is started, the voltage output increases as the alt\
ernator rpm increases. When the
voltage output becomes greater than the battery voltage, current for recharging\
flows from terminal B. Simulta-
neously, volt age at terminal L increases and the potential difference between battery and terminal L disappears,
causing the discharge warning light to go off. When the voltage output exceeds the regulator adjustment volt-
age, the transistor inside the IC regulator regulates the voltage so tha\
t the voltage from the alternator remains
constant.
±
CHARGING SYSTEM System Circuit, OperationCH±3
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