1991 LEXUS SC400 diagram

WIRING DIAGRAM
DIAGNOSTIC CHART
±
SRS AIRBAG TroubleshootingAB±87
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Wiring Diagram
CENTER AIRBAG SENSOR ASSEMBLY CONNECTOR
No.SymbolTerminal NameNo.SymbolTerminal Name
18E2Ground
2±SRRH Front Airbag Sensor (±)9LAAirbag Warning Light
3+SRRH Front Airbag Sensor (+)10D±Squib (±)
4+SLLH Front Airbag Sensor (+)11D+Squib (+)
5±SLLH Front Airbag Sensor (±)12TcDiagnosis
6+BBattery (ECU±B Fuse)13E1Ground
7IG2Power Source (IGN Fuse)14AccPower Source (CIG Fuse)
AL1Electrical Connection Check
MechanismBL2Electrical Connection Check
Mechanism
AB±33SRS AIRBAG ± Troubleshooting
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Circuit Inspection
Diag. Code (Normal)Source Voltage Drop
CIRCUIT DESCRIPTION
The airbag system is equipped with a voltage±increase circuit (DC±DC\
converter) in the center airbag
sensor assembly in case the source voltage drops.
When the battery voltage drops, the voltage±increase circuit (DC±DC c\
onverter) functions to increase
the voltage of the airbag system to normal voltage.
The diagnosis system malfunction display for this circuit is different to other circuits±when the airbag
warning light remains lit up and the diagnostic code is a normal code, source voltage d\
rop is indicated.
Malfunction in this circuit is not recorded in the center airbag sensor assembly, and approx. 10 se-
conds after the source voltage returns to normal, the airbag warning lig\
ht automatically goes off.
Code No.
Diagnosis
(Normal)Source voltage drop.
DIAGNOSTIC CHART
Preparation.
Does airbag warning light turn on after
approx. 10 seconds?
Check battery and charging system
(See page CH±1). Check diagnostic code, and if a
malfunction code is output,
perform troubleshooting according
to malfunction code.
If a normal code is output,
replace center airbag sensor
assembly.
WIRING DIAGRAM
AB±40SRS AIRBAG
± Troubleshooting
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DIAGNOSTIC CHART (Cont'd)
Check front airbag sensor.Replace front airbag sensor.
Repair or replace spiral cable.Check spiral cable. Repair or replace harness or connector
between center airbag sensor assembly and
front airbag sensor (See page AB±20).
Repair or replace harness or connector
between center airbag sensor assembly and
spiral cable.
WIRING DIAGRAM
AB±43SRS AIRBAG ± Troubleshooting
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DIAGNOSTIC CHART
Preparation.
Check front airbag sensor circuit.
(Measure voltage between terminal +SR
or +SL of center airbag sensor assembly
connector and body ground).
From the results of the above inspection, the
malfunctioning part can now be considered
normal. To make sure of this, use the
simulation method to check.
Repair or replace harness or connector
between center airbag sensor assembly and
spiral cable. Check front airbag sensor circuit.
(Measure resistance between terminals +SR
and ±SR, +SL and ±SL of center airbag
sensor assembly connector).
Check squib circuit.
Check center airbag sensor assembly.
Check squib.
Check spiral cable.Repair or replace spiral cable.
Go to step [ 7 ].
Replace center airbag sensor
assembly.
Replace steering wheel pad.
Go to Code 15 (See page
AB±68).
Repair or replace harness or
connector between center airbag
sensor assembly and front airbag
sensor (See page AB±20).
WIRING DIAGRAM
AB±49SRS AIRBAG ± Troubleshooting
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DIAGNOSTIC CHART (Cont'd)
Check spiral cable.Repair or replace spiral cable.
Check harness between center airbag
sensor assembly and spiral cable.Repair or replace harness or
connector between center airbag
sensor assembly and spiral cable.
Check center airbag sensor assembly.Replace center airbag sensor
connector.
From the results of the above inspection,
the malfunctioning part can now be
considered normal. To make sure of this,
use the simulation method to check.
WIRING DIAGRAM
AB±55SRS AIRBAG ± Troubleshooting
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WIRING DIAGRAM
combination meter
AT±66 combination meter
DIAGNOSTIC CHARTDIAGNOSTIC CHART
±
A304E (1UZ±FE) AUTOMATIC TRANSMISSION TROUBLESHOOTINGAT±79
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AT±66
IN±33
WIRING DIAGRAM
DIAGNOSTIC CHARTDIAGNOSTIC CHART
±
A304E (1UZ±FE) AUTOMATIC TRANSMISSION TROUBLESHOOTINGAT±83
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