lock LEXUS SC400 1991 Service Repair Manual

NOTICE: When connecting the battery after clearing the malfunction code, always\
do it with the igni-
tion switch in LOCK position. When the battery has been reconnected, turn the ignition switch to
ACC or ON position after at least 2 seconds have elapsed.
If the battery is reconnected with the ignition switch in ACC or ON posi\
tion, or the ignition switch
is turned to ACC or ON within 2 seconds of connecting the battery, it is possible that the diagnosis
system will not operate normally.
 DIAGNOSTIC TROUBLE CODE CHART
Proceed to the appropriate flow chart in step  in accordance with the malfunction code found in step 
or .
 CIRCUIT INSPECTION \b REPAIR
Find out if the problem lies in a sensor, actuator or TROUBLESHOOTING, and repair the problem. After
the problem part is repaired, reinstall the disassembled parts. Do not s\
tart work until at least 90 seconds
after the ignition switch is turned to the LOCK position and the negative (±\
) terminal cable is disconnected.
CAUTION: If incorrect procedure is used, a malfunction may occur in the system o\
r there is the dan-
ger that airbag may be accidentally deploy during the repair operation. \
Carefully read the GENERAL
DESCRIPTION (See page RS±2) and the cautions for each operation, and perform repairs in the cor-
rect order using the correct methods.
HINT: The following illustration for the CIRCUIT INSPECTION shows each conne\
ctor for the SRS squib
circuit.
 
















 
















 
















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SUPPLEMENTAL RESTRAINT SYSTEM TROUBLESHOOTINGRS±55
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10 MALFUNCTION CODE CLEARANCEWhen all the malfunction codes found in steps  and  have been repaired, clear the malfunction codes.
11 DIAGNOSTIC TROUBLE CODE CHECK
After repeating ignition switch ON±OFF operation (ON: wait 20 secs, OFF: \
wait 20 secs.) 5 times, check
the diagnostic trouble codes. If a code is displayed, return to step  and troubleshoot the displayed mal-
function code.
NOTICE: When connecting the battery after clearing the malfunction code, always\
do it with the igni-
tion switch in LOCK position. When the battery has been reconnected, turn the ignition switch to
ACC or ON position after at least 20 seconds have elapsed.
If the battery is reconnected with the ignition switch in ACC or ON posi\
tion, or the ignition switch
is turned ACC or ON within 20 seconds of connecting the battery, it is possible that the diagnosis
system will not operate normally.
12 CONFIRMATION TEST Check the warning light again and confirm that all the malfunctions have been\
repaired. If the warning light
indicates an abnormality, repeat the operation again from step .
RS±56
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SRS WARNING LIGHT CHECK
DIAGNOSIS INSPECTION
(a) Turn the ignition switch to ACC or ON and check that the SRSwarning light lights up.
(b) Check that the SRS warning light goes out after approx. 6
seconds.
HINT:
wWhen the ignition switch is at ACC or ON and the SRS
warning light remains on, the TROUBLESHOOTING
has detected a malfunction code.
w If, after approx. 6 seconds have elapsed, the SRS
warning light sometimes lights up or the SRS warning
light lights up even when the ignition switch is OFF, a
short in the SRS warning light circuit can be considered
likely. Proceed to SRS warning light system (always lit
up when ignition switch LOCK position) on page
RS±119 .
DIAGNOSTIC TROUBLE CODE CHECK
Using diagnosis check wire:
1. OUTPUT DIAGNOSTIC TROUBLE CODE
(a) Turn the ignition switch to ACC or ON position and wait approx. 20 seconds.
(b) Using SST, connect terminals Tc and E of the DLC2. SST 09843±18020
NOTICE: Never make a mistake with the terminal connec-
tion position as this will cause a malfunction.
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SUPPLEMENTAL RESTRAINT SYSTEM TROUBLESHOOTINGRS±59
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DIAGNOSTIC TROUBLE CODE MATRIX CHART
If a malfunction code is displayed during the diagnostic trouble code chec\
k, check the circuit listed for that
code in the table below (Proceed to the page given for that circuit).
 DTC No.\
 \
Diagnosis Page
 (Normal)*1\
 \

Source voltage drop RS±68
 11\
 \

Short in squib circuit or front airbag sensor circuit (to ground) RS±70
 12\
 \

Short in squib circuit or front airbag sensor circuit (to B+) RS±78
 13\
 \

Short in squib circuit (between D+ wire harness and D± wire harness\
) RS±85
 14\
 \

Open in squib circuit (between D+ wire harness and D± wire harness)\
 RS±92
 15\
 \

Open in front airbag sensor circuit RS±97
 22*2\
 \

SRS warning light system malfunction RS±102
 31\
 \

Center airbag sensor assembly malfunction RS±108
 53\
 \

Short in squib circuit (between P+ wire harness and P± wire harness\
) RS±110
 54\
 \

Open in squib circuit (between P+ wire harness and P± wire harness)\
 RS±115
HINT:
*
1 When the SRS warning light remains lit up and the diagnostic trouble co\
de is the normal code, this means
a source voltage drop.
*
2 Code 22 is recorded when a malfunction occurs in the SRS warning light \
system. If an open malfunction
occurs in the SRS warning light system, the SRS warning light does not light up, s\
o that until the malfunction
is repaired, the diagnostic trouble code (including 22) cannot be conf\
irmed.
PROBLEM SYMPTOM CHART
Proceed with troubleshooting of each circuit in the table below.
\
 \
Problem Symptom Inspection Item Page
\
 

\



With the ignition switch at ACC or ON, the SRS warning light
sometimes lights up after approx. 6 seconds have elapsed
SRS warning light system
(Always lit upwhen ignition switch isRS±119\
 

\



SRS warning light lights up even when ignition switch is in
the LOCK position (Always lit up when ignition switch is
LOCK position)RS±11 9
\
 \

Diagnostic trouble code not displayed.
Tc terminal circuitRS±121
\
 \

Diagnostic trouble code continuously displayed.
Tc terminal circuitRS±121
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YESNO
INSPECTION PROCEDURE
1Preparation.
P1. Turn ignition switch LOCK.
2. Disconnect battery negative (±) terminal cable, andwait at least 90 seconds.
3. Connect battery negative (±) terminal cable.
4. Disconnect center airbag sensor assembly con- nector.
5. Turn ignition switch ON. But do not start engine.
6. Measure voltage at IG
2 or ACC on connector wire
harness side of center airbag sensor assembly and
operate electric system (defogger, wiper, headlight,
heater blower, etc.)
Voltage: 6 V ± 11.5 V at IG
2 and ACC.
7. Turn electric system switch OFF.
8. Turn ignition switch LOCK.
9. Disconnect battery negative (±) terminal cable, and wait at least 90 seconds.
10. Remove voltmeter and connect center airbag sen- sor assembly connector.
11. Connect battery negative (±) terminal cable.
2Does SRS warning light turn off after approx. 10 seconds?
C
PTurn ignition switch ACC or ON and wait at least 20 sec-
onds.
Clear malfunction code. Turn ignition switch LOCK and
wait at least 20 seconds.
Operate electric system checked in
(5) and check
that SRS warning light goes off after approx. 10 sec-
onds.
Check diagnostic trouble code, and if a malfunction code
is output, perform trouble shooting according to mal-
function code. If a normal code is output, replace center
airbag sensor assembly.
Check battery and charging system.
(See page CH±1)
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SUPPLEMENTAL RESTRAINT SYSTEM TROUBLESHOOTINGRS±69
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OKNG
OKNG
7Check D squib.
C
OK
Hint
P1. Turn ignition switch LOCK.
2. Disconnect battery negative (±) terminal cable, andwait at least 90 seconds.
3. Connect steering wheel pad (squib) connector.
4. Connect negative (±) terminal cable to battery, and wait at least 2 seconds.
1. Turn ignition switch ACC or ON, and wait at least 20
seconds.
Clear malfunction code. Turn ignition switch LOCK
and wait at least 20 seconds.
2. Turn ignition switch ACC or ON, and wait at least 20
seconds.
3. Using SST, connect terminals Tc and E
1 of DLC2.
SST 09843±18020
4. Check diagnostic trouble code.
Diagnostic trouble code 11 is not output.
Codes other than code 11 may be output at this time, but
this is not relevant to this check.
Replace steering wheel pad.
8Check P squib.
C
OK
Hint
P1. Turn ignition switch LOCK.
2. Disconnect battery negative (±) terminal cable, and
wait at least 20 seconds.
3. Connect front passenger airbag assembly (squib) connector.
4. Disconnect steering wheel pad (squib) connector.
5. Connect negative (±) terminal cable to battery and wait at least 2 seconds.
1. Turn ignition switch ACC or ON, and wait at least 20
seconds.
Clear malfunction code. Turn ignition switch LOCK
and wait at least 20 seconds.
2. Turn ignition switch ACC or ON, and wait at least 20
seconds.
3. Using SST, connect terminals Tc and E
1 of DLC2.
4. Check diagnostic trouble code.
Diagnostic trouble code 11 is not output.
Codes other than code 11 nay be output at this time, but
they are not relevant to this check.
Replace front passenger airbag assembly.
RS±76
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OKNG
OKNG
5Check P squib circuit.
C
OK
Measure voltage at P+ on spiral cable side of connector
between spiral cable and steering wheel pad.
Voltage: Below 1 V
Go to step

6Check center airbag sensor assembly.
C
OK
Hint
P1. Turn ignition switch LOCK.
2. Disconnect negative (±) terminal cable from bat-
tery.
3. Connect connector to center airbag sensor assem- bly.
4. Using a service wire, connect D
+ and D± on spiral
cable side connector between spiral cable and
steering wheel pad.
5. Using a service wire, connect P
+ and P± on center
airbag sensor assembly side of connector between
center airbag sensor assembly a dn front passen-
ger airbag assembly.
6. Connect negative (±) terminal cable to battery, and wait at least 2 seconds.
1. Turn ignition switch ACC or ON and wait at least 20 seconds.
Clear malfunction code. Turn ignition switch LOCK
and wait at least 20 seconds.
2. Turn ignition switch ACC or ON, an s wait at least 20 seconds.
3. Using SST, connect terminals Tc and E
1 of DLC2
SST 09843±18020
4. Check diagnostic trouble code.
Diagnostic trouble code 12 is not output.
Code other than code 12 may be output at this time, but
this is not relevant to this check.
Replace center airbag sensor assembly.
RS±82
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OKNG
OKNG
7Check D squib.
C
OK
Hint
P1. Turn ignition switch LOCK.
2. Disconnect battery negative (±) terminal cable, andwait at least 90 seconds.
3. Connect steering wheel pad (squib) connector.
4. Connect negative (±) terminal cable to battery, and wait at least 2 seconds.
1. Turn ignition switch ACC or ON and wait at least 20 seconds.
Clear malfunction code. Turn ignition switch LOCK
and wait at least 20 seconds.
2. Turn ignition switch ACC or ON, and wait at least 20
seconds.
3. Using SST, connect terminals Tc and E
1 of DLC2
SST 09843±18020
4. Check diagnostic trouble code.
Diagnostic trouble code 12 is not output.
Codes other t han code 12 may be output at this time, but
is not relevant to this check.
Replace steering wheel pad.
8Check P squib.
C
OK
Hint
P1. Turn ignition switch LOCK.
2. Disconnect battery negative (±) terminal cable, and
wait at least 90 seconds.
3. Connect front passenger airbag assembly (squib) connector.
4. Disconnect steering wheel pad (squib) connector.
5. Connect negative (±) terminal cable to battery, and wait at least 2 seconds.
1. Turn ignition switch ACC or ON and wait at least 20 seconds.
Clear malfunction code. Turn ignition switch LOCK
and wait at least 20 seconds.
2. Turn ignition switch ACC or ON, and wait at least 20
seconds.
3. Using SST, connect terminals Tc and E
1 of DLC2.
4. Check diagnostic trouble code.
Diagnostic trouble code 12 is not output.
Codes other t han code 12 may be output at this time, but
they are not relevant to this check.
Replace center airbag sensor assembly.
±
SUPPLEMENTAL RESTRAINT SYSTEM TROUBLESHOOTINGRS±83
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OKNG
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.
9Check spiral cable.
C
OK
P1. Turn ignition switch LOCK.
2. Disconnect connector between center airbag sen-sor assembly and spiral cable.
3. Turn ignition switch ON.
Measure voltage at D+ on spiral cable side of connector
between spiral cable and steering wheel pad.
Voltage: Below 1 V
Repair or replace spiral cable.
Repair or replace harness or connector between center airbag sensor asse\
mbly and spiral cable.
RS±84±
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OKNG
OKNG
3Check center airbag sensor assembly.
C
OK
Hint
P1. Using a service wire, connect D+ and D±.
2. Using a service wire, connect P
+ and P±.
3. Connect negative (±) terminal cable to battery.
4. Clear malfunction.
5. Turn ignition switch LOCK, and wait at least 20 sec- onds.
6. Disconnect service wire of D
+ and D±.
7. Turn ignition switch ACC or ON, and wait at least 20
seconds.
1. Turn ignition switch LOCK, and wait at least 20 sec- onds.
2. Turn ignition switch ACC or ON, and wait at least 20 seconds.
3. Using SST, connect terminals Tc and E
1 of DLC2.
SST 09842±18020
4. Check diagnostic trouble code.
Diagnostic trouble code 13 is not output.
Codes other t han code 13 may be output at this time, but
this is not relevant to this check.
Replace center airbag sensor assembly.
4Check D squib.
C
OK
Hint
P1. Turn ignition switch LOCK.
2. Disconnect battery negative (±) terminal cable, and wait at least 90 seconds.
3. Connect steering wheel pad (squib) connector.
4. Connect negative (±) terminal cable to battery.
5. Clear malfunction.
1. Turn ignition switch LOCK, and wait at least 20 sec- onds.
2. Turn ignition switch ACC or ON, and wait at least 20 seconds.
3. Using SST, connect terminals Tc and E
1 of DLC2.
SST 09843±18020
4. Check diagnostic trouble code.
Diagnostic trouble code 13 is not output.
Codes other t han code 13 may be output at this time, but
this is not relevant to this check.
Replace steering wheel pad.
RS±88
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