2000 LEXUS GS400 ignition

± BODY ELECTRICALTROUBLESHOOTING
BE±7
2308 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
INTERIOR LIGHT SYSTEM
This system uses the multiplex communication system, so check diagnosis system of the multiplex commu-
nication system before you proceed with troubleshooting.
SymptomSuspect AreaSee page
All the lights do not come ON.1. DOME Fuse
2. Body ECU NO.2BE±21
±
The light does not come ON when the driver's door is opened.1. Driver's Door Courtesy Switch
2. Wire HarnessBE±60
±
The light does not come ON when the passenger's door is
opened.1. Passenger's Door Courtesy Switch
2. Wire HarnessBE±60
±
The light does not come on when the rear±right door is opened.1. Rear±Right Door Courtesy Switch
2. Wire HarnessBE±60
±
The light does not come on when the rear±left door is opened.1. Rear±Left Door Courtesy Switch
2. Wire HarnessBE±60
±
Only one of the bulbs comes ON.Bulb±
The illumination does not fade out when all the doors are closed.1. Courtesy Switch
2. Wire HarnessBE±60
±
The illumination does not fade out immediately when the ignition
switch is turned to ACC or ON within 15 seconds after all the
doors are closed.1. Ignition Switch
2. RADIO NO.2 Fuse
3. GAUGE Fuse
4. Wire HarnessBE±31
BE±21
BE±21
±
The illumination does not fade out immediately when all the doors
are locked within 15 seconds after they are closed.1. Door Unlock Detection Switch
2. Wire HarnessBE±131
±
Interior light does not light up.
(in front personal light)1. Bulb
2. Front Personal Light
3. Wire Harness±
BE±60
±
Front personal light does not light up.
1. Bulb
2. Front Personal Light
3. Wire Harness±
BE±60
±
Rear personal light does not light up.
1. Bulb
2. Rear Personal Light
3. Wire Harness±
BE±60
±
Vanity light does not light up.
1. Bulb
2. Vanity Light
3. Wire Harness±
BE±60
±
Luggage compartment light does not light up.
1. Bulb
2. Luggage Compartment Door Courtesy Switch
3. Wire Harness±
BE±60
±
Courtesy light does not light up.
1. Bulb
2. Door Courtesy Switch
3. Wire Harness±
BE±60
±

BE±8
± BODY ELECTRICALTROUBLESHOOTING
2309 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
BACK±UP LIGHT SYSTEM
SymptomSuspect AreaSee page
Back±Up Light does not light up.
1. GAUGE Fuse
2. Ignition Switch
3. Wire Harness
4. BulbBE±21
BE±31
±
±
Back±Up Light remains always on.1. Park/ Neutral Position Switch
2. Wire HarnessDI±372
±
Only one light does not light up.1. Bulb
2. Wire Harness±
±
STOP LIGHT SYSTEM
SymptomSuspect AreaSee page
Stop light does not light up.
1. STOP Fuse
2. Stop Light Switch
3. Light Failure Relay
4. Wire HarnessBE±21
BE±70
BE±92
±
Stop light always lights up.1. Stop Light Switc
2. Wire HarnessBE±70
±
Only one light always lights up.Wire Harness±
Only one light does not light up.1. Bulb
2. Wire Harness±
±
HEADLIGHT CLEANER SYSTEM
SymptomSuspect AreaSee page
ºHeadlight Cleaner Systemº does not operate
(All)
1. H±LP CLN Fuse
2. WASHER Fuse
3. Ignition Switch
4. Headlight Cleaner Switch
5. Headlight Cleaner Relay
6. Headlight Cleaner Motor
7. Headlight Cleaner Nozzle and Hose
8. Wire HarnessBE±21
BE±21
BE±31
BE±73
BE±73
±
±
±
Washer fluid does not spray.Headlight Cleaner Nozzle and Hose±
WIPER AND WASHER SYSTEM
SymptomSuspect AreaSee page
Wipers and washer do not operate.
1. WIP Fuse
2. Wiper Switch
3. Wiper Motor
4. Wire HarnessBE±21
BE±77
BE±77
±
Wipers do not operate in LO, HI or MIST.
1. Wiper Switch
2. Wiper Motor
3. Wire HarnessBE±77
BE±77
±
Wipers do not operate in INT.
1. Wiper Switch
2. Wiper Motor
3. Wire HarnessBE±77
BE±77
±
Washer motor does not operate.
1. WASHER Fuse
2. Washer Switch
3. Washer Motor
4. Wire HarnessBE±21
BE±77
BE±77
±
Wipers do not operate when washer switch ON.
1. WASHER Fuse
2. Washer Switch
3. Wiper Motor
4. Wire HarnessBE±21
BE±77
BE±77
±

± BODY ELECTRICALTROUBLESHOOTING
BE±11
2312 Author: Date:
2000 LEXUS GS300/GS400 (RM718U) The Key related power window operations does not operate with
driver side door key cylinder.
(Master switch operation is normal.)
TROUBLESHOOTING NO.3BE±111
Power window does not operate with multi±function transmitter.
(Windows operate normally with master switch.)TROUBLESHOOTING NO.4BE±111
Window moves down without being ordered during the up opara-
tion.TROUBLESHOOTING NO.5BE±111
POWER DOOR LOCK CONTROL SYSTEM
This system uses the multiplex communication system, so check diagnosis system of the multiplex commu-
nication system before you proceed with troubleshooting.
SymptomSuspect AreaSee page
All the doors cannot be locked or unlocked.
(Power Window Control System is normal.)1. Door Lock Control Switch
2. Wire Harness
3. Body No.1 ECUBE±131
±
DI±776
Only one side door lock control does not operate.
1. Door Lock Motor
2. Wire Harness
3. Each Door ECUBE±131
±
±
Door key related function does not operate.
1. Door Key Lock and Unlock Switch
2. Wire Harness
3. Each Door ECU
4. Body No.1 ECUBE±131
±
±
DI±776
Key confinement prevention function does not operate.
1. Key Unlock Warning Switch
2. Door Courtesy Switch
3. Wire Harness
4. Each Door ECUBE±31
BE±60
±
±
Luggage compartment door opener function does not operate.
1. Luggage Compartment Door Opener Switch
2. Luggage Compartment Door Opener Motor
3. Wire Harness
4. Body No.1 ECUBE±131
BE±131
±
DI±776
THEFT DETERRENT SYSTEM
This system uses the multiplex communication system, so check diagnosis system of the multiplex commu-
nication system before you proceed with troubleshooting.
SymptomSuspect AreaSee page
The system cannot be set.
1. Indicator Light
2. Key Unlock Warning Switch
3. Door Unlock Detection Switch
4. Engine Hood Courtesy Switch
5. Luggage Compartment Door Courtesy Switch
6. Wire Harness
7. Each Door ECU
8. Body No.1 ECUBE±150
BE±31
BE±131
BE±150
BE±60
±
±
DI±776
The system cannot be canceled when the ignition switch is turned
to ON with key.
1. Key Unlock Warning Switch
2. Ignition Switch
3. RAD NO.2 Fuse
4. Wire Harness
5. Body No.1 ECUBE±31
BE±31
BE±21
±
DI±776
The system cannot be canceled when the luggage compartment
door is unlocked with key.1. Luggage Compartment Door Courtesy Switch
2. Wire Harness
3. Body No.1 ECUBE±60
±
DI±776
The system does not operate when the engine hood is opened.
1. Engine Hood Courtesy Switch
2. Wire Harness
3. Body No.1 ECUBE±150
±
DI±776

BE±12
± BODY ELECTRICALTROUBLESHOOTING
2313 Author: Date:
2000 LEXUS GS300/GS400 (RM718U) The system does not operate when the ignition switch is turned to
ACC without using a key or transmitter.
1. Ignition Switch
2. Key Unlock Warning Switch
3. Transmitter
4. Wire Harness
5. Body No.1 ECUBE±31
BE±31
BE±157
±
DI±776
Some of the system does not operate.
(Headlight does not light up.)
1. Headlight System
2. Wire Harness
3. Body No.2 ECU
4. Body No.1 ECUBE±3
±
DI±820
DI±776
Some of the system does not operate.
(Taillight does not light up.)
1. Taillight System
2. Wire Harness
3. Body No.2 ECU
4. Body No.1 ECUBE±3
±
DI±820
DI±776
Some of the system does not operate.
(Theft Deterrent Horn or Horn does not sound.)
1. HORN Fuse
2. Theft Deterrent Horn
3. Horn
4. Horn Relay
5. Wire Harness
6. Body No.1 ECUBE±21
BE±150
BE±250
BE±250
±
DI±776
While the warning is given, the system cannot be canceled by
unlocking the door with key or transmitter.1. Door Key Lock and Unlock Switch
2. Wire Harness
3. Body No.1 ECUBE±131
±
DI±776
While the warning is given, the system cannot be canceled by
turning the ignition switch to ACC or ON with key.
1. Ignition Switch
2. Key Unlock Warning Switch
3. RAD NO.2 Fuse
4. ECU±IG Fuse
5. Wire Harness
6. Body No.2 ECU
7. Body No.1 ECUBE±31
BE±31
BE±21
BE±21
±
DI±820
DI±776
The system operates for more than 60 seconds.Body No.1 ECUDI±776
WIRELESS DOOR LOCK CONTROL SYSTEM
This system uses the multiplex communication system, so check diagnosis system of the multiplex commu-
nication system before you proceed with troubleshooting.
HINT:
Troubleshooting of the wireless door lock control system is based on the premise that the door lock
control system is operating normally. Accordingly, before troubleshooting the wireless door lock control
system, first make certain that the door lock control system is operating normally.
If the trouble still reappears even though there are no abnormalities in any of the other circuits, then
check and replace the Wireless Door Lock Control Receiver as the last step.
SymptomSuspect AreaSee page
All functions of wireless door lock control system do not operate.
1. Transmitter
2. Wireless Door Lock Control Receiver
3. Wire Harness
4. Body No.1 ECUBE±157
BE±157
±
DI±776
Wireless door lock operates, but the buzzer does not sound.
(The buzzer does not sound when the customize function prohib-
its.)1. Wireless Door Lock Buzzer
2. Wireless Door Lock Control Receiver
3. Wire HarnessBE±157
BE±157
±

BE01L±11
I01349
Ignition SwitchKey Unlock Warning Switch
BE±30± BODY ELECTRICALIGNITION SWITCH AND KEY UNLOCK WARNING
SWITCH
2331 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
IGNITION SWITCH AND KEY UNLOCK WARNING SWITCH
LOCATION

BE0H4±04
I01256
1 2 3 4
5 6 7 8 LOCKACC
ON
START
I04031
From Back Side
± BODY ELECTRICALIGNITION SWITCH AND KEY UNLOCK WARNING
SWITCHBE±31
2332 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
INSPECTION
1. INSPECT IGNITION SWITCH CONTINUITY
Switch positionTester connectionSpecified condition
LOCK±No continuity
ACC2 ± 3Continuity
ON2 ± 3 ± 4
6 ± 7Continuity
START1 ± 2 ± 4
6 ± 7 ± 8Continuity
If continuity is not as specified, replace the switch.
2. INSPECT IGNITION SWITCH CIRCUIT
Connect the switch connector and inspect the connector on
wire harness side from the back side, as shown.
Tester connectionConditionSpecified condition
2 ± GroundConstantBattery positive voltage
3 ± GroundIgnition switch ACC or ONBattery positive voltage
4 ± GroundIgnition switch ONBattery positive voltage
6 ± GroundIgnition switch ON or STARTBattery positive voltage
7 ± GroundConstantBattery positive voltage
8 ± GroundIgnition switch STARTBattery positive voltage
If circuit is not as specified, inspect the circuits connected to oth-
er parts.

I04265
I01663
1 2 OFF
ON
3 4
I04032
Wire Harness Side BE±32
± BODY ELECTRICALIGNITION SWITCH AND KEY UNLOCK WARNING
SWITCH
2333 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
3. INSPECT IGNITION KEY ILLUMINATION OPERATION
Connect the positive (+) lead from the battery to terminal 1 and
the negative (±) lead to terminal 2, and check that the indicator
light lights up.
If operation is not as specified, replace the switch.
4. INSPECT IGNITION KEY ILLUMINATION CIRCUIT
(See page DI±843)
5. INSPECT KEY UNLOCK WARNING SWITCH CONTI-
NUITY
Switch positionTester connectionSpecified condition
OFF (Key removed)±No continuity
ON (Key set)1 ± 2Continuity
If continuity is not as specified, replace the switch.
6. INSPECT KEY UNLOCK WARNING SWITCH CIRCUIT
(See page DI±828)
Connect the switch connector and inspect the connector on
wire harness side from the back side, as shown.
Tester connectionConditionSpecified condition
1 ± GroundConstantContinuity
If circuit is not as specified, inspect the circuits connected to oth-
er parts.

BE0H8±04
I10257
Driver Side Junction Block

GAUGE Fuse

TAIL Fuse

Taillight Control Relay

Body ECU No.2
Combination Switch

Light Control Switch

Headlight Dimmer SwitchIgnition Switch
Daytime Running
Light Main Relay
(w/ D.R.L. System) HeadlightsEngine Room No.1 Junction Block

H±LP L LWR Fuse

H±LP R LWR Fuse

H±LP L UPR Fuse (w/o D.R.L System)

H±LP R UPR Fuse (w/o D.R.L System)

Headight Control Relay D.R.L.: Daytime Running Light
Automatic Light Control Sensor
Headlights
Taillights
Engine Room No.2 Junction Block

Headight Dimmer (D.R.L. No.2) Relay

H±LP R UPR Fuse (w/ D.R.L System)

H±LP L UPR Fuse (w/ D.R.L System)
Light Control ECU Light Control ECU
Daytime Running Light No.3 and No.4 Relay
(w/ D.R.L. System)
Daytime Running Light Resister
± BODY ELECTRICALHEADLIGHT AND TAILLIGHT SYSTEM
BE±33
2334 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
HEADLIGHT AND TAILLIGHT SYSTEM
LOCATION
The vehicle shown in this illustration is ºGS400º.
All components of ºGS300º other than the ones used for engine are same as ºGS400º.