2000 LEXUS GS400 airbag

AC±2
± AIR CONDITIONINGAIR CONDITIONING SYSTEM
2687 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
9. SUPPLEMENTAL RESTRAINT SYSTEM (SRS)
The Lexus GS 300/ 400 is equipped with an SRS (Supplemen-
tal Restraint System) such as the driver and passenger airbag.
Failure to carry out service operations in the correct sequence
could cause the SRS to unexpectedly deployed during servic-
ing, possibly leading to a serious accident. Further, if a mistake
is made in servicing the SRS, it is possible the SRS may fail to
operate when required. Before servicing ( including removal or
installation of parts, inspection or replacement), be sure to read
the following item carefully, then follow the correct procedure
described in repair manual.

BE01I±09
± BODY ELECTRICALBODY ELECTRICAL SYSTEM
BE±1
2302 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
BODY ELECTRICAL SYSTEM
PRECAUTION
HINT:
Take care to observe the following precautions when performing inspections or removal and replacement
of body electrical related parts.
1. HEADLIGHT SYSTEM

Halogen bulbs have pressurized gas inside and require special handling. They can burst if scratched
or dropped. Hold a bulb only by its plastic or metal case. Don't touch the glass part of a bulb with bare
hands.

When high voltage socket of discharge headlight is touched with the light control switch HEAD, high
voltage of 20,000 V is momentarily generated. This might lead to a serious accident.

Never connect the tester to the high voltage socket of discharge headlight for measurement, as this
leads to a serious accident because of high voltage.

When performing operation related to the discharge headlight, make sure to do it in the place with no
water of rain to prevent electric shock, with light control switch OFF, battery terminal removed, connec-
tor of light control ECU disconnected.

When performing operation related to the discharge headlight, make sure to do it after assembling has
been completely over and never light up without a bulb installed.

Do not light up the discharge headlight using another power source except vehicle's.

When there is a defect on the discharge headlight or any shock has been applied to it, replace the light
with a new one.
Even if the light operates normally, there is a possibility that the fail±safe function works.
2. SRS (SUPPLEMENTAL RESTRAINT SYSTEM)
The LEXUS GS300/ 400 is equipped with an SRS (Supplemental Restraint System) such as the driver airbag
and front passenger airbag. Failure to carry out service operation in the correct sequence could cause the
SRS to unexpectedly deploy during servicing, possibly leading to a serious accident. Before servicing (in-
cluding removal or installation of parts, inspection or replacement), be sure to read the precautionary notices
in the RS section.
3. COMBINATION METER SYSTEM
The cold cathode tube connectors (Connector ºKºand ºLº) in the combination meter are charged with high
voltage AC current when power is supplied, so do not touch them when they are charged.

± BODY ELECTRICALTROUBLESHOOTING
BE±9
2310 Author: Date:
2000 LEXUS GS300/GS400 (RM718U) Washer fluid does not operate.
Washer Hose and Nozzle±

When wiper switch is in HI position, the wiper blade is in contact
with the body.

When the wiper switch is OFF, the wiper blade does not retract
or the retract position is wrong.
1. Wiper Motor *1
2. Wire harness *1BE±77
±
*1: Inspect wiper arm and blade set positions.
COMBINATION METER
This system uses the multiplex communication system, so check diagnosis system of the multiplex
communication system before you proceed with troubleshooting.
Refer to DI section for warning light or indicator light not described in the table below.
SymptomSuspect AreaSee page
Driver seat belt warning light does not light up.
1. Bulb
2. Driver Buckle Switch CIrcuit
3. Meter Circuit Plate
4. Wire Harness
5. Body No.2 ECU±
BE±92
BE±92
±
DI±820
Passenger seat belt warning light does not light up.
1. Clock System
2. Passenger Buckle Switch CIrcuit
3. Occupant Detection Sensor
4. Meter Circuit Plate
5. Wire Harness
6. Body No.1 ECUBE±227
BE±92
BE±92
BE±92
±
DI±776
SRS warning light does not light up.
1. MPX±B Fuse
2. SRS±B Fuse
3. Bulb
4. Meter Circuit Plate
5. Wire Harness
6. Airbag Sensor AssemblyBE±21
BE±21
±
BE±92
±
DI±550
Hi±beam indicator light does not light up.
1. Bulb
2. Meter Circuit Plate
3. Wire Harness
4. Headlight System±
BE±92
±
BE±3
Turn indicator light does not light up.
1. Bulb
2. Meter Circuit Plate
3. Wire Harness
4. Turn Signal and Hazard Warning System±
BE±92
±
BE±3
ABS warning light does not light up.
1. GAUGE Fuse
2. Bulb
3. Meter Circuit Plate
4. Wire Harness
5. ABS, TRAC and VSC ECUBE±21
±
BE±92
±
DI±387
TRAC warning light does not light up.
1. GAUGE Fuse
2. Bulb
3. Meter Circuit Plate
4. Wire Harness
5. ABS, TRAC and VSC ECUBE±21
±
BE±92
±
DI±473

BE0HH±07
I01359
Brake Master Cylinder

Brake Fluid Level
Warning Switch
Combination Meter
and Telltale Light
Assembly
Airbag Sensor Assembly Parking Brake Switch
Driver Side
Junction Block

GAUGE Fuse

SRS±B FuseIgnition Switch
ECM
Washer Tank

Washer Level
Warning Switch Engine Room No.1
Junction Block

MPX±B Fuse
Seat Belt Buckle Switch
Rheostat Light Control
ABS, TRAC and VSC ECU
Clock Assembly

Passenger Seat Belt
Waning Light
BE±80
± BODY ELECTRICALCOMBINATION METER
2381 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
COMBINATION METER
LOCATION
The vehicle shown in this illustration is ºGS400º.
All components of ºGS300º other than the ones used for engine are same as ºGS400º.

I04251

Combination Meter Wiring Circuit ± 2
Left Turn Indicator
Right Turn Indicator
Hi±beam Indicator
SRS Warning
Washer Level Indicator
Headlight leveling
Indicator
Malfunction
Indicator
VSC Warning
ABS Warning
VSC OFF Indicator
SLIP Indicator IG+IG+ IG+
IG+
IG+
IG+Combination Meter ECU
A14 A15 A16 A13 A12 B18 A10 to HEAD FuseB15B3B2
A7
B12Headlight Dimmer Switch
Airbag Sensor Assembly
Washer Fluid Level
Warning Switch
Healight Leveing
Contorl ECU
ECM
ABS, TRAC and
VSC ECU Turn Singal
Flasher RelayODO/TRIP Switch
RESET Switch to Combination Meter ECU
to Combination Meter ECUU8
U3
U10
U9
U4
SRS +B BE±84
± BODY ELECTRICALCOMBINATION METER
2385 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)

Clock (Passenger seat belt warning light)
Tilt and telescopic ECU
Fuel main sender gauge
Fuel sub sender gauge
ABS, TRAC and VSC ECU (Speed signal)
Speed control unit
Headlight dimmer switch
Ground
Window washer level warning switch
Body control No.2 ECU
ECM
ABS, TRAC and VSC ECU (VSC warning light)
ABS, TRAC and VSC ECU (SLIP warning light)
ABS, TRAC and VSC ECU (TRAC OFF warning light)
ABS, TRAC and VSC ECU (ABS warning light)
ABS, TRAC and VSC ECU (Brake warning light)
GAUGE fuse
Turn signal flasher (Left turn side)
Turn signal flasher (Right turn side)
Light control rheostat (+B)
Light control rheostat (Signal)
Light control rheostat (Ground)
PANEL fuse
Airbag sensor assembly
MPX+B fuse
DOME+B fuse
HEAD±RH fuse
Igniter
Headlight beam leveling control ECU
Ground
Telltale light assembly (IG+)
Telltale light assembly (ODO/TRIP switch)
Telltale light assembly (Right turn signal)
Telltale light assembly (RESET switch)
Telltale light assembly (Left turn signal)
GroundWiring connector side No.1
1
1
2
3
4
5
6
7
8
10
11
12
13
14
15
16
17
1 1
1
2
3
4
5
6
9
12
13
14
15
16
18
22
1 1
1
3
4
8
9
10 U B A
± BODY ELECTRICALCOMBINATION METER
BE±85
2386 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)

I04253

Meter Circuit Plate ± 2
Combination Meter ECU
SLIP Indicator
TRAC OFF Indicator
Window Washer Level Warning
ABS Warning
VSC Warning
Brake Fluid Level Warning
ECT SNOW Indicator
Low Oil Pressure Warning
ECT PWR Indicator
Discharge Warning
CRUISE MAIN Indicator
Seat Belt Warning
Rear Light Indicator
Headlight Leveling Indicator
SRS Warning
Open Door Warning
Fog Light IndicatorA/T 2 Indicaor
Engine Oil Level Indicator
Malfunction Indicator
Fuel Level Indicator
Headlight Indicator (USA)
Taillight Indicator (CANADA) ODO/
TRIP
Display
PanelIG+
SLIP
TRC OFF
WASHER
ABS
VSC
BRAKE
ECT SNOW
OIL P
ECT PWR
CHARGE
CRUISE
SEAT BELT
Rr LIGHT
HEAD LVL
AIRBAG
SRS +B
DOOR
FR FOG
COM1
SEG30
TEST1
TEST2
TEST3
GroundCHECK
ENG
IG+
FUEL
IG+
BEAM±
BEAM+ SRS +BTAIL A/T R
A/T L
A/T N
A/T D
OIL LVLDIM+
A/T 2
A/T 3
A/T 4F12
A/T PF11
F10
F9
F8
F5
F4
F2
F1
C7
C5
C3
D12
D8 E11
E10
E9
E8
E7
E6
J1
J33
D6
D4Hi±Beam Indicator
D2 E20
E19
E18
E17
E16
E15
E14
E13
E12
E3
E1 E5
E4A/T 3 Indicaor
A/T 4 Indicaor
A/T P Indicaor
A/T R Indicaor
A/T L Indicaor
A/T N Indicaor
A/T D Indicaor
T1
T2
T3
T4
~~
D10 BE±88
± BODY ELECTRICALCOMBINATION METER
2389 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)

IN0EI±01
BO4111
Negative Cable
IN±10
± INTRODUCTIONFOR ALL OF VEHICLES
10 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
FOR ALL OF VEHICLES
PRECAUTION
1. FOR VEHICLES EQUIPPED WITH SRS AIRBAG AND
SEAT BELT PRETENSIONER
(a) The LEXUS GS400/GS300 is equipped with an SRS
(Supplemental Restraint System), such as the driver air-
bag, front passenger airbag assembly, side airbag as-
sembly and seat belt pretensioners.
Failure to carry out service operations in the correct se-
quence could cause the supplemental restraint system to
unexpectedly deploy during servicing, possibly leading to
a serious accident.
Further, if a mistake is made in servicing the supplemental
restraint system, it is possible the SRS may fail to operate
when required. Before servicing (including removal or
installation of parts, inspection or replacement), be sure
to read the following items carefully, then follow the cor-
rect procedure described in this manual.
(b) GENERAL NOTICE
(1) Malfunction symptoms of the supplemental re-
straint system are difficult to confirm, so the diag-
nostic trouble codes become the most important
source of information when troubleshooting. When
troubleshooting the supplemental restraint system,
always inspect the diagnostic trouble codes before
disconnecting the battery (See page DI±552).
(2) Work must be started after 90 seconds from the
time the ignition switch is turned to the ºLOCKº posi-
tion and the negative (±) terminal cable is discon-
nected from the battery.
(The supplemental restraint system is equipped
with a back±up power source so that if work is
started within 90 seconds of disconnecting the neg-
ative (±) terminal cable from the battery, the SRS
may deploy.)
When the negative (±) terminal cable is discon-
nected 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
the each memory system. Then when work is fin-
ished, reset the clock and audio systems as before.
This vehicle has power tilt and power telescopic
steering, power seat and power outside rear view
mirror, which are all equipped with memory function,
it is not possible to make a record of the memory
contents. So when the work is finished, therefore it
will be necessary to explain this fact to the custom-
er, and ask the customer to adjust the features and