2000 LEXUS GS400 key

1. Insert master key in the key cylinder.
2. Require key code deletion from hand±held tester.
(Security indicator blinks)
3. Remove the master key.
HINT:
When the key cannot be pulled out in the step 3, key code deletion is canceled.
(Security indicator is OFF.) END
(Key code erased.)
Within 120 sec.
Within 10 sec.
BE±246
± BODY ELECTRICALENGINE IMMOBILISER SYSTEM
2547 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
(2) Using LEXUS hand±held tester:

BE02Q±15
I01376
ECM
Transponder Key Coil
Driver Side Junction Block

IGN Fuse Transponder Key Amplifier
± BODY ELECTRICALENGINE IMMOBILISER SYSTEM
BE±247
2548 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
LOCATION
The vehicle shown in this illustration is ºGS400º.
All components of ºGS300º other than the ones used for engine are same as ºGS400º.

BE0G8±09
I04266
1 2
BE±248
± BODY ELECTRICALENGINE IMMOBILISER SYSTEM
2549 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
INSPECTION
INSPECTION TRANSPONDER KEY COIL CONTINUITY
Check that continuity exists between terminals 1 and 2.
If continuity is not as specified, replace the coil.

BE19B±01
± BODY ELECTRICALTROUBLESHOOTING
BE±3
2304 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
TROUBLESHOOTING
PROBLEM SYMPTOMS TABLE
IGNITION SWITCH AND KEY UNLOCK WARNING SWITCH
This system uses the multiplex communication system, so check diagnosis system of the multiplex commu-
nication system before you proceed with troubleshooting.
Ignition Switch:
SymptomSuspect AreaSee page
Ignition switch is not set to each position.4. Ignition switch
5. Power source circuitBE±31
±
Key Unlock Warning Switch:
SymptomSuspect AreaSee page
Key unlock warning system does not operate.
(The buzzer does not sound when the driver's door is opened with
the ignition OFF and key inserted)1. Key Unlock Warning Switch
2. Door Courtesy Switch
3. Wire HarnessBE±31
BE±60
±
Key unlock warning system does not operate.
(The buzzer sounds when the ignition key is ACC or ON)1. Ignition Switch
2. Wire HarnessBE±31
±
HEADLIGHT AND TAILLIGHT SYSTEM:
This system uses the multiplex communication system, so check diagnosis system of the multiplex commu-
nication system before you proceed with troubleshooting.
HINT:
To inspect the bulb and light control ECU, replace them with the ones working normally and judge whether
they work normally or not.
SymptomSuspect AreaSee page
ºAutomatic light control systemº does not operate.
1. Automatic Light Control Sensor
2. Light Control Switch
3. Door Courtesy Switch
4. Wire Harness
5. Body No.2 ECUBE±37
BE±37
BE±60
±
DI±820
Auto turn±off system does not operate when the driver's door is
opened.1. Drivers Door Courtesy SwitchBE±60
Auto turn±off system:
Headlight and taillight do not come on.1. Body ECU No.2
2. Wire HarnessDI±820
±
Auto turn±off system:
Headlight and taillight stay on.1. Body ECU No.2
2. Wire HarnessDI±820
±
USA:
SymptomSuspect AreaSee page
Only one headlight comes on.
1. Bulb
2. *Light Control ECU
3. Wire Harness±
±
±
ºLO±Beamº does not light (All).
1. Headlight Control Relay
2. *Light Control ECU
3. Wire HarnessBE±37
±
±
ºLO±Beamº does not light (One side).
1. Bulb
2. H±LP L±LWR Fuse
3. H±LP R±LWR Fuse
4. *Light Control ECU
5. Wire Harness±
BE±21
BE±21
±
±
ºHI±Beamº does not light (All).1. Headlight Dimmer Switch
2. Wire HarnessBE±37
±

± 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.