1991 LEXUS SC400 clock

DIAGNOSTIC CODE CLEARANCE
1. After repair of the trouble areas, the diagnostic code retainedin the ECU memory must be cleared out by removing the EFI
fuse (30A) from R/B No. 2 for 10 seconds or more, with the
ignition switch OFF.
HINT:
wCancellation can also be done by removing the battery
negative (±) terminal, but in this case, other memory
systems (clock, etc.) will also be cancelled out.
w If it is necessary to work on engine components
requiring removal of the battery terminal, a check must
first be made to see if a diagnostic code has been
recorded.
2. After cancellation, road test the vehicle to check that a normal
code is now read on the ºCHECKº engine warning light.
If the same diagnostic code appears, it indicates that the
trouble area has not been repaired thoroughly.
±
ENGINE TROUBLESHOOTING Diagnosis SystemTR±13
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219
1E
2
IK1
6
I22
IHC
10
C
13 C 14 C 19 C20 C 16 C17 C18 C 6
412 97812
3A
5
3C
5
3F
6
L±R
L±R
V±R
RRR
V
V±W
B
R±Y W L±R
L±R
TRIP SW AND THEFT DETERRENT INDICATOR LIGHT 15A
CIG
TRIP METER
CIRCUIT
CLOCK SPEED
FROM POWER SOURCE SYSTEM
(
SEE PAGE 56 )
ENGINE OIL LEVEL
WARNING SW T15
C12 ,
3,C14
E6 COMBINATION METER
A
BC
OIL TEMP. OIL LEVEL
E20
W±B
ED C
15
A
1
B 2 AI39
SHORT CONNECTOR
,23
A
2 TO DOOR LOCK
CONTROL RELAY
L±R
W±B
BR
V±R
BR
BR
E2ACC
R
P
21
BR
BR
S22 BP
P
R
C1
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177
SRS AIRBAG
NOTICE: When inspecting or repairing the SRS AIRBAG, perform the operation in accord\
ance with the
following precautionary instructions and the procedure and precautions in the Repair Manual for the applicable
model year.

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 diagnostic codes before disconnecting the
battery.

Work must be started after 30 seconds or longer from the time the Ignition SW is set to the ªLOCKº 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 30 seconds of
disconnecting the negative (±) terminal cable of the battery, the airbag may be deployed.)
When the negative (±) terminal cable is disconnected from the battery, memory of the clock and audio systems
will be cancelled. So before starting work, make a record of the contents memorized by each me\
mory system.
Then when work is finished, reset the clock and audio system as before.
When the vehicle has tilt and telescopic steering, power seat, outside r\
ear view mirror and power shoulder
belt anchorage, which are all equipped with memory function, it is not possible to make a record of the memory
contents. So when the operation is finished, it will be necessary to explain this\
fact to the customer, and
request the customer to adjust the features and reset the memory.
To avoid erasing the memory of each memory system, never use a back±up \
power supply from outside the
vehicle.

When removing the steering wheel pad or handling a new steering wheel pad, keep the pad upper surfa\
ce
facing upward. Also, lock the lock lever of the twin lock type connector\
at the rear of the pad and take care
not to damage the connector.
(Storing the pad with its metallic surface up may lead to a serious accident if \
the airbag inflates for some
reason).

Store the steering wheel pad where the ambient temperature remains below\
93 °C (200 °F), without high
humidity and away from electrical noise.

Never use airbag parts from another vehicle. When replacing airbag parts\
, replace them with new parts.

Never disassemble or repair the steering wheel pad, center airbag sensor asse\
mbly or front airbag sensors.

Before repairing the body, remove the airbag sensors if during repair shocks are likely to be app\
lied to the
sensors due to vibration of the body or direct tapping with tools or oth\
er parts.

Do not reuse a steering wheel pad or front airbag sensors.
After evaluating whether the center airbag sensor assembly is damaged or not, decide whether or not to reuse
it. (See the Repair Manual for the method for evaluating the center airbag\
sensor assembly.)

When troubleshooting the airbag system, use a high±impedance (Min. 1\
0k W/V) tester.

The vehicle wiring harness exclusively for the airbag system is distinguish\
ed by corrugated yellow tubing, as
are the connectors.

Do not measure the resistance of the airbag squib.
(It is possible this will deploy the airbag and is very dangerous.)

If the wire harness used in the airbag system is damaged, replace the wh\
ole wire harness assembly.
When the connector to the airbag front sensors can be repaired alone (when \
there is no damage to the wire
harness), use the repair wire specially designed for the purpose.
(Refer to the Repair Manual for the applicable Model year for details o\
f the replacement method.)

INFORMATION LABELS (NOTICES) are attached to the periphery of the airbag componen\
ts. Follow the
instructions on the notices.
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