2000 LEXUS GS400 engine

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.

BE0FY±09
I01377
Horn
Horn Switch Engine Room No.1
Junction Block

HORN Fuse
Theft Deterrent Horn
Engine Room No.2
Junction Block

Horn Relay
± BODY ELECTRICALHORN SYSTEM
BE±249
2550 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
HORN 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.

± BODY ELECTRICALTROUBLESHOOTING
BE±5
2306 Author: Date:
2000 LEXUS GS300/GS400 (RM718U) ºHI±Beamº does not light (All).
1. Headlight Dimmer Switch
2. Daytime Running Light Main Relay
3. Wire HarnessBE±37
BE±37
±
ºHI±Beamº does not light (One side).
1. Bulb
2. H±LP L±UPR Fuse
3. H±LP R±UPR Fuse
4. Daytime Running Light No.3 Relay
5. Wire Harness±
BE±21
BE±21
BE±37
±
ºFlashº does not light.
1. Headlight Dimmer Switch
2. Daytime Running Light Main Relay
3. Wire HarnessBE±37
BE±37
±
Headlight does not come on.
1. Headlight Control Relay
2. Daytime Running Light Main Relay
3. Daytime Running Light No.2, 3, 4 Relay
4. Headlight Dimmer Switch
5. Light Control Switch
6. Wire Harness
7. *Light Control ECU
8. BulbBE±37
BE±37
BE±37
BE±37
BE±37
±
±
±
Headlight does not come on with light control switch in HEAD.
1. Light Control Switch
2. *Light Control ECU
3. Wire HarnessBE±37
±
±
Headlight does not go out with light control switch in OFF.
1. Headlight Control Relay
2. *Light Control ECU
3. Wire HarnessBE±37
±
±
Headlight flickers.
1. Bulb
2. *Light Control ECU
3. Wire Harness±
BE±37
±
Headlight is dark.
1. Bulb
2. *Light control ECU
3. Wire Harness±
±
±
Taillight does not come on with light control switch in TAIL.
1. Taillight Control Relay (Instrument Panel J/B)
2. Light Control Switch
3. Wire HarnessBE±37
±
±
Taillight does not go out with light control switch in OFF.
1. Taillight Control Relay
2. Light Control Switch
3. Wire HarnessBE±37
BE±37
±
Headlight does not come on with engine running and light control
switch in OFF.
1. ECU±B Fuse
2. GAUGE Fuse
3. Daytime Running Light Main Relay
4. Daytime Running Light No.2, 3, 4 Relay
5. Generator L Terminal
6. Parking Brake Switch
7. Wire HarnessBE±21
BE±21
BE±37
BE±37
DI±853
BE±92
±
*: HID Type

± 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

± BODY ELECTRICALTROUBLESHOOTING
BE±15
2316 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
GARAGE DOOR OPENER SYSTEM
SymptomSuspect AreaSee page
The equipment of which code has been registered does not oper-
ate.1. Garage Door Opener Switch
2. Wire Harness
3. *BE±235
±
±
LED does not light up. (Even though either switch is pressed.)1. Garage Door Opener Switch
2. Wire HarnessBE±235
±
LED does not light up. (Only one switch is pressed.)Garage Door Opener SwitchBE±235
* As the GARAGE DOOR OPENER on the vehicle side seems to be normal, check the OPENER on the
equipment side, of which code has been registered.
ENGINE IMMOBILIZER SYSTEM
SymptomSuspect AreaSee page
Engine immobilizer system does not operate.See DIAGNOSIS SYSTEMDI±726
HORN SYSTEM
SymptomSuspect AreaSee page
Horn system does not operate.
1. HORN Fuse
2. Horn Relay
3. Horn Switch
4. Horn
5. Wire HarnessBE±21
BE±250
BE±250
BE±250
±
Horns blow all the time.
1. Horn Relay
2. Horn Switch
3. Wire HarnessBE±250
BE±250
±
One horn operates but the other horn does not operate.1. Horn
2. Wire HarnessBE±250
±
Horns operate abnormally.
1. Horn Relay
2. Horn
3. Wire HarnessBE±250
BE±250
±

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.