1991 LEXUS SC400 warning

The procedures are presented in a step±by±step format:
wThe illustration shows what to do and where to do it.
w The task heading tells what to do.
w The detailed text tells how to perform the task and gives
other information such as specifications and warnings.
Example:
This format provides the experienced technician with a FAST
TRACK to the information needed. The upper case task
heading can be read at a glance when necessary, and the
text below it provides detailed information. Important specifi-
cations and warnings always stand out in bold type.
REFERENCES
References have been kept to a minimum. However, when
they are required you are given the page to refer to.
SPECIFICATIONS
Specifications are presented in bold type throughout the text
where needed. You never have to leave the procedure to look
up your specifications. They are also found at the end of each
section, for quick reference.
CAUTIONS, NOTICES, HINTS:
w CAUTIONS are presented in bold type, and indicate
there is a possibility of injury to you or other people.
w NOTICES are also presented in bold type, and indicate
the possibility of damage to the com ponent being
repaired.
w HINTS are separated from the text but do not appear in
bold. They provide additional information to help you
efficiently perform the repair.
SI UNIT
The UNIT given in this manual are primarily expressed with
the SI UNIT (International System of Unit), and alternately ex-
pressed in the metric system and in the yard/pound system.
Example:
Torque: 30 N Vm (310 kgf Vcm, 22 ft Vlbf)
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INTRODUCTION How to Use This ManualIN±3
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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 con-
tents memorized by each memory system. Then when work
is finished, reset the clock and audio systems as before.
When the vehicle has power tilt and power telescopic steer-
ing, power seat, power outside rear 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 ask 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.
3. Even in cases of a minor collision where the airbag does not deploy, the front airbag sensors and the steering wheel pad
should be inspected. (See page AB±9)
4. Never use airbag parts from another vehicle. When replacing parts, replace them with new parts.
5. Before repairs, remove the airbag sensors if shocks are likely
to be applied to the sensors during repairs.
6. The center airbag sensor assembly contains mercury. After
performing replacement, do not destroy the old part. When
scrapping the vehicle or replacing the center airbag sensor
assembly itself, remove the center airbag sensor assembly
and dispose of it as toxic waste.
7. Never disassemble and repair the front airbag sensors, center airbag sensor assembly or steering wheel pad in order
to reuse it.
8. If the front airbag sensors, center airbag sensor assembly or steering wheel pad have been dropped, or if there are cracks,
dents or other defects in the case, bracket or connector,
replace them with new ones.
9. Do not expose the front airbag sensors, center airbag sensor assembly or steering wheel pad directly to hot air or flames.
10. U s e a v o l t / o h m m e t e r w i t h h i g h i m pedance (10 kW/V
minimum) for troubleshooting of the electrical circuit.
11. Information labels are attached to the periphery of the airbag components. Follow the notices.
12. After work on the airbag system is completed, perform the
airbag warning light check (See page AB±30).
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INTRODUCTION Precautions for Vehicles Equipped with SRS AirbagIN±9
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DIAGNOSIS SYSTEM
Warning for A/C compressor lock
If compressor lock occurs during air conditioner operation, the
( A/C ) switch indicator on the air conditioner control assembly
starts blinking to warn the driver.
When this occurs, check for compressor lock (code 22) using diag-
nostic code check then proceed to inspect the circuit or the com-
ponent.
Compressor lock sensor circuit page AC±54.
LIST OF OPERATION METHODS
By operating each of the air conditioner control switches as shown in the \
diagram below, it is possible to enter
the diagnosis check mode. AC±26
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AIR CONDITIONING SYSTEM Troubleshooting
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Diag. Code 22Airbag Warning Light System Malfunction
CIRCUIT DESCRIPTION
The airbag warning light is located on the combination meter.
When the airbag system is normal, the airbag warning light lights up for\
approx. 6 seconds after the
ignition switch is turned from LOCK position to ACC or ON position, and then turns off automatically.
If there is a malfunction in the airbag system, the airbag warning light\
lights up to inform the driver of
the abnormality.
When terminals Tc and E of the TDCL are connected, the diagnostic code is displayed by t\
he blinking
of the airbag warning light.
The airbag warning light circuit is equipped with an electrical connecti\
on check mechanism which
detects when the connector to the center airbag sensor assembly is not p\
roperly connected.
If the connector to the center airbag sensor assembly is not properly co\
nnected, the airbag warning
light will not light up.
Diagnostic code 22 is recorded when a malfunction occurs in the airbag w\
arning light system.
If an OPEN malfunction occurs in the airbag warning light system, the ai\
rbag warning light does not
light up, so that until the malfunction is repaired, the diagnostic code\
s (including code 22) cannot be
confirmed.
Code No.Diagnosis
22
Open circuit in airbag warning light system.22
Center airbag sensor assembly malfunction.
AB±74±
SRS AIRBAG Troubleshooting
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OKNG
1
2
3
4
5
6
6
OK
OK
YES
YES NG
NG NO
NO
Check connection of center airbag sensor
assembly connector.
Preparation.
Check airbag warning light circuit.
Does airbag warning light come on?
Is new ECU ±B fuse burnt out again? GO to step
Repair.
Repair airbag warning light circuit
(See page BE±150).
Check terminal LA of center
airbag sensor assembly and
electrical connection check
mechanism. If normal, replace
center airbag sensor assembly.
Using simulation method,
reproduce malfunction symptoms
(See page IN±20).
Check harness between ECU ±B fuse and
airbag warning light, and ECU±B fuse and
center airbag sensor assembly. 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.
Check ECU ±B fuse.
DIAGNOSTIC CHART
Troubleshooting for this system is different for when the airbag warning light does not light up and for
when diagnostic code 22 is output. Confirm the problem symptoms first before\
selecting the appropriate
troubleshooting procedure.
HINT: If airbag warning light does not light up, perform the following troub\
leshooting:
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SRS AIRBAG TroubleshootingAB±75
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Check ECU±B fuse.
NG
OK
1
6Go to step
(1) Disconnect battery negative (±) terminal cable, and wait at least 20 seconds.
(2) Remove steering wheel pad (See page AB±14).
When storing steering wheel pad, keep upper
surface of pad facing upward.
NG
OKRepair.
Check connection of center airbag sensor assembly connector.2
3Preparation.
INSPECTION PROCEDURE
HINT: If airbag warning light does not light up, perform the following troubl\
eshooting:
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SRS AIRBAG TroubleshootingAB±77
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4
5
6
Check terminal LA of center airbag sensor assem-
bly and electrical connection check mechanism.
If normal, replace center airbag sensor assembly.
NG
OK
(1) Disconnect negative (±) terminal cable from battery.
(2) Connect center airbag sensor assembly.
(3) Connect negative (±) terminal cable to battery.
(4) Turn ignition switch ACC or ON. Voltage: 10±14 V
Check operation of airbag warning light.
(1) Disconnect center airbag sensor assembly.
(2) Connect negative (±) terminal cable to battery.
(3) Turn ignition switch ACC or ON.
Measure voltage LA terminal of harness side
connector of center airbag sensor assembly.
Repair airbag warning light circuit
(see page BE±150).
NG
Using simulation method, reproduce
malfunction symptoms (See page In±20).NG
OK
Check airbag warning light circuit.
Does airbag warning light come on?
Is new ECU±B fuse burnt out again?
From the results of the above inspection, the malfunctioning part can now be considered norm\
al. To
make sure of this, use the simulation method to check.
Check harness between ECU±B fuse and airbag warning light, and ECU±B fus\
e and center airbag sensor
assembly.
AB±78±
SRS AIRBAG Troubleshooting
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OK
Check operation of airbag warning light.
NG1
WIRING DIAGRAM
2Is diagnostic code 41 output again? System is normal.
Check harness between ECU±B
fuse and center airbag sensor as-
sembly. If normal, replace center
airbag sensor assembly.
Perform troubleshooting according to
malfunction code output. NO
YES
Diag. Code 41Malfunction Stored in Memory
CIRCUIT DESCRIPTION
If a malfunction occurs in the airbag system, malfunction codes 11 to 31 may be output, and when the
battery is disconnected after the malfunction is repaired, malfunction codes 11 to 31 will be cleared,
but code 41 will be output instead.
So long as the cancellation operation for a malfunction stored in memory (\
See page
AB±32) is not per-
formed, code 41 is stored in the center airbag sensor assembly and the airbag w\
arning light remains
lit up.
Code No.Diagnosis
41
Malfunction recorded in memory.41
Center airbag sensor assembly malfunction.
DIAGNOSTIC CHART
AB±82±
SRS AIRBAG Troubleshooting
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