Page 211 of 1111

N22087
21
N21865
(a)
1(b)
2
2
1
N22088
21
N22089
21
N21865
(a)
(b)
2
1
1 2 BE±172
± BODY ELECTRICALPOWER SEAT CONTROL SYSTEM
2473 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
(c) Disconnect the leads from the terminals.
(d) Approximately 60 seconds later, connect the positive (+)
lead from the battery to terminal 2 (1) and the negative (±)
lead to terminal 1 (2), check that the seat cushion begins
to descend.
If operation is not as specified, replace the seat adjuster.
13. INSPECT LIFTER MOTOR OPERATION
(a) Connect the positive (+) lead from the battery to terminal
1 and the negative (±) lead to terminal 2, check that the
motor turns counterclockwise.
(b) Reverse the polarity, check that the motor turns clock-
wise.
If operation is not as specified, replace the seat adjuster.
14. INSPECT LIFTER MOTOR PTC THERMISTOR OPERA-
TION
(a) Connect the positive (+) lead from the battery to terminal
2 (1), the positive (+) lead from the ammeter to terminal
1 (2) and the negative (±) lead to the battery negative (±)
terminal, then move the seat cushion to the highest posi-
tion.
(b) Continue to apply voltage, check that the current changes
to less than 1 ampere within 4 to 90 seconds.
(c) Disconnect the leads from the terminals.
(d) Approximately 60 seconds later, connect the positive (+)
lead from the battery to terminal 1 (2) and the negative (±)
lead to terminal 2 (1), check that the seat cushion begins
to descend.
If operation is not as specified, replace the seat adjuster.
15. INSPECT RECLINING MOTOR OPERATION
(a) Connect the positive (+) lead from the battery to terminal
1 and the negative (±) lead to terminal 2, check that the
motor turns counterclockwise.
(b) Reverse the polarity, check that the motor turns clock-
wise.
If operation is not as specified, replace the seat adjuster.
Page 275 of 1111
BE0G0±05
1
CLOCK WILL NOT OPERATEPASSENGER SEAT BELT WARNING LIGHT DOES NOT OPERATE
I04264
Wire Harness Side5
4
3
6
1RAD NO.2 Fuse
DOME Fuse
Combination
Meter
Body ECU
No.2
Ground ACC
+B
PBEW
ILL
E Clock Assembly
± BODY ELECTRICALCLOCK
BE±227
2528 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
CLOCK
TROUBLESHOOTING
HINT:
Troubleshoot the clock according to the table below.
TroubleshootingNo.
Passenger seat belt warning light does not light up.1
Clock will not operate1
Clock loses or gains time2
± 1.5 seconds / day
INSPECT CLOCK CIRCUIT
(See page DI±849)
TROUBLESHOOTING NO.1
(a) Check that the battery positive voltage is 10 ± 16 V.
If voltage is not as specified, replace the battery.
(b) Check that the DOME and RAD NO.2 fuses are not
blown.
If the fuse is blown, replace the fuse and check for short.
(c) Troubleshoot the clock as follows.
HINT:
Inspect the connector on the wire harness side.
Page 276 of 1111

Ye s
Ye sNo
No
Is there battery positive voltage between terminal +B and
body ground?
Is there battery positive voltage between terminal ACC and
body ground?
Replace clock.+B wire harness faulty.
Ye sNo
Is there continuity between terminal GND and
body ground?Ground wire harnss faulty. ACC wire harness faulty.
2 CLOCK LOSES OR GAINS TIME
I04264
Wire Harness Side5
4
3
6
1RAD NO.2 Fuse
DOME Fuse
Combination
Meter
Body ECU
No.2
Ground ACC
+B
PBEW
ILL
E Clock Assembly
Ye s
Is there battery positive voltage between terminal +B and
body ground?
Adjust or replace clock.Bellow 10 V
Locate cause and repair, or recharge battery.
Ye s
Is there battery positive voltage between terminal ACC and
body ground?Bellow 10 V
Locate cause and repair, or recharge battery.
BE±228
± BODY ELECTRICALCLOCK
2529 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
TROUBLESHOOTING NO.2
(a) Check that the battery positive voltage is 10 ± 16 V.
If voltage is not as specified, replace the battery.
(b) Inspect the error of the clock.
Allowable error (per day): ± 1.5 seconds
If the error exceeds the allowable error, replace the clock.
(c) Check that the clock adjusting button is sticking in posi-
tion and has failed to return.
If the error exceeds the allowable error, replace the clock.
(d) Troubleshoot the clock as follows.
HINT:
Inspect the connector on the wire harness side.
Page 277 of 1111
BE0G1±08
I01374
Ignitioin SwitchClock Assembly
Driver Side Junction Block
SRS ACC Fuse
Passenger Side
Junction Block
DOME Fuse
± BODY ELECTRICALCLOCK
BE±229
2530 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
LOCATION
Page 306 of 1111

± 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
Page 311 of 1111

BE±14
± BODY ELECTRICALTROUBLESHOOTING
2315 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
w/o Driving Position Memory System:
SymptomSuspect AreaSee page
Mirror does not operate.
1. Mirror Switch
2. Wire Harness
3. Body No.2 ECU
4. Driver and Passenger Door ECUBE±176
±
DI±820
DI±856
DI±889
Mirror operates abnormally.
1. Mirror Switch
2. Mirror Motor
3. Wire Harness
4. Body No.2 ECU
5. Driver and Passenger Door ECUBE±176
BE±176
±
DI±820
DI±856
DI±889
ELECTRO CHROMIC MIRROR SYSTEM
SymptomSuspect AreaSee page
Electro Chromic Inner Mirror does not operate.
1. ECU±IG Fuse
2. Electro Chromic Inner Mirror
3. Wire HarnessBE±21
BE±182
±
Electro Chromic Outer Mirror does not operate.
1. ECU±IG Fuse
2. Electro Chromic Outer Mirror
3. Electro Chromic Inner Mirror
4. Wire HarnessBE±21
BE±182
BE±182
±
SEAT HEATER SYSTEM
SymptomSuspect AreaSee page
Seat heaters do not operate.
(Driver's and Passenger's)
1. SEAT HTR Fuse
2. Seat Heater Switch (D, P)
3. Wire Harness
4. Seat HeaterBE±21
BE±185
±
BE±185
Driver's seat heater does not operate.1. Seat Heater Switch (D, P)
2. Wire HarnessBE±185
±
Passenger's seat heater does not operate.1. Seat Heater Switch (D, P)
2. Wire HarnessBE±185
±
Seat heater temperature is too hot.Seat HeaterBE±185
FUEL LID OPENER SYSTEM
SymptomSuspect AreaSee page
Fuel lid opener system does not operate.
1. FUEL OPN Fuse
2. Fuel Lid Opener Switch
3. Fuel Lid Opener Motor
4. Wire HarnessBE±21
BE±188
BE±188
±
AUDIO SYSTEM
SymptomSuspect AreaSee page
Audio system abnormal operation.TROUBLESHOOTINGSBE±196
CLOCK SYSTEM
SymptomSuspect AreaSee page
Passenger seat belt warning system does not light up.TROUBLESHOOTING NO.1BE±227
Clock will not operate.TROUBLESHOOTING NO.1BE±227
Clock loses or gains time.TROUBLESHOOTING NO.2BE±227
Page 363 of 1111
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.
Page 366 of 1111
I04250
Combination Meter Wiring Circuit ± 1
:Speedometer
:Tachometer
:Fuel Receiver Gauge
:Engine Coolant
Temperature
Receiver Gauge
Speed Control Unit
CLOCK
to GAUGE Fuse
to MPX±B Fuse
to SRS Fuse
Tilt and Telescopic ECU
Body ECU NO.2ECM (GS400)
Ignitor (GS300)
Fuel Main Sender GaugeGround
Fuel Sub Sender Gauge
Light Control Rheostat
Illuminations
ABS, TRAC and VSC ECU
ABS, TRAC and VSC ECU Speed Signal Passenger seat
belt warning
Rr LIGHTS
SEAT BELT
OIL PRESS
OIL LEVEL
DOOR IG+
SRS +BA/T P
A/T R
A/T N
A/T D
A/T 4
A/T 3
A/T 2
A/T L
CRUISE MPX+BIG+IG+
5V
+B
to ECUto
PANEL
Fuse B4
B5
B6
B9
A5
A17A3A8 B16
LCDECU S
T
F
E
Power Source
Brake
Buzzer A11A2 A1 A6
B1
B13
B14A4
B22 ECU
ECU
ECU
S
T
F
E
CHARGE
FUEL LVL
ECT PWR
ECT SNOW TAIL or HEAD
Ground IG+IG+ IG+ IG+
+B
± BODY ELECTRICALCOMBINATION METER
BE±83
2384 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)