2000 LEXUS GS400 lights

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.

BE0HA±02
I04033
HI
Flash OFFTAIL HEAD AUTO
LO
± BODY ELECTRICALHEADLIGHT AND TAILLIGHT SYSTEM
BE±37
2338 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
INSPECTION
1. FAIL±SAFE FUNCTION
(Light Control ECU)
When input error is inspected.
When input voltage is not within the range of operation voltage (9 to 16 V),
lighting of the headlight stops. As soon as the voltage comes within the range,
it lights up again.
However if the input voltage becomes low after lighting up,
sufficient voltage is maintained until light of bulb completely goes off.
When output error is inspected (Open or short).
When light flushing is inspected.
When an error occurs in the output voltage (open or short) or flushing symptom
occurs on the bulb, lighting of the headlight stops, the condition is maintained
until power is turned ON again (headlight dimmer switch OFF " ON).
In this case, it can not be judged whether lighting malfunction is caused by an
output error or other reasons (fuse blown out, etc.).
Check that there is no error in fuse and wiring (including power source) and
replace the bulb in the first place, when the error still appears, replace the light
control ECU.
2. INSPECT LIGHT CONTROL SWITCH CONTINUITY
Switch positionTester connectionSpecified condition
OFF±No continuity
TAIL15 ± 16Continuity
HEAD14 ± 15 ± 16Continuity
AUTO13 ± 16Continuity
If continuity is not as specified, replace the switch.
3. INSPECT HEADLIGHT DIMMER SWITCH CONTINU-
ITY
Switch positionTester connectionSpecified condition
Low beam17 ± 18Continuity
High beam8 ± 17Continuity
Flash8 ± 9 ± 17Continuity
If continuity is not as specified, replace the switch.

I04038
I04039
BE±42
± BODY ELECTRICALHEADLIGHT AND TAILLIGHT SYSTEM
2343 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)8 ± Ground
Headlight dimmer switch HIGH beam or FLASHContinuity
1 ± GroundIgnition switch LOCK or ACCNo voltage
1 ± GroundIgnition switch ON or STARTBattery positive voltage
5 ± GroundEngine StopNo voltage
5 ± GroundEngine RunningBattery positive voltage
7 ± GroundConstantBattery positive voltage
9 ± GroundConstantBattery positive voltage
If circuit is specified, try replacing the relay with a new one.
If circuit is not as specified, inspect the circuits connected to oth-
er parts.
16. INSPECT AUTOMATIC LIGHT CONTROL
AUTO ON:
(a) Turn the ignition switch ON.
(b) Turn the light control switch to AUTO.
(c) Gradually cover the top of the sensor.
(d) Check the accessory lights and the headlights should turn
ON.
17. INSPECT AUTOMATIC LIGHT CONTROL
AUTO OFF:
(a) Gradually expose the sensor.
(b) Check the headlights and the accessory lights should turn
OFF.
18. INSPECT LIGHT±OFF CONDITION
(a) Turn the ignition switch ON.
(b) Gradually cover the top of the sensor.
Lights auto ON:
(c) Check that the lights go off under the following conditions.
(1) Light control switch is OFF.
(2) The area surrounding the sensor gets bright.
(3) The driver's door is opened with the ignition switch
OFF.

I01254
Wire Harness Side
4 3 2 1
± BODY ELECTRICALHEADLIGHT AND TAILLIGHT SYSTEM
BE±43
2344 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
19. INSPECT LIGHTS±ON CONDITION
(a) Open the driver's door while the ignition switch is OFF.
(b) Turn the light control switch to AUTO leaving the door
open and cover the top of the sensor, and verify that the
lights go on when the ignition switch is turned ON.
20. INSPECT AUTOMATIC LIGHT CONTROL SENSOR
CIRCUIT
Connector disconnected:
Disconnect the connector from the sensor and inspect the con-
nector on the wire harness side, as shown in the table.
Tester connectionConditionSpecified condition
3 ± GroundConstantContinuity
1 ± GroundIgnition switch LOCK or ACCNo voltage
1 ± GroundIgnition switch ONBattery positive voltage
4 ± GroundIgnition switch LOCK or ACCNo voltage
4 ± GroundIgnition switch ON5.2 ± 9.0 V
If circuit is as specified, perform the inspection on the following
page.
If the circuit is not as specified, inspect the circuit connected to
other parts.

I07728
20.9 mm (0.823 in.)
0.4°
3 m (9.84 ft)
W
V Center
Line
V LH Line V RH Line
H
HRH Line3 cm
(0.57°)LH
Line
W
I04297
Beam Angle Gauge
(Vertical Alignment)
Acceptable
Range
Bubble
± BODY ELECTRICALHEADLIGHT AND TAILLIGHT SYSTEM
BE±47
2348 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
(c) Check the headlight aimming.
(1) Prepare the thick white colored paper.
(2) Stand the paper perpendicularly and ensure the
distance from it to the head lights is 9.84 ft.
(3) Ensure that the center line of vehicle and the paper
are at a 90 degree angle as shown in the illustration.
(H line)
(4) Engine running.
(5) Draw a horizontal line on the paper where the head
lights of the vehicle are to be.
(6) Draw a vertical line on the paper where the center
line of the vehicle is to be. (V center line)
(7) Take an appropriate measure to avoid affecting the
other light. (V RH and LH lines)
NOTICE:

Disconnect the connector of the other light to avoid
heat affection from the light because the outer lens of
the head light assembly is made of synthetic resin.
When connecting the connector again take care not
to wake the aiming out of adjustment.

When covering the headlight, finish it within 3 min-
utes.
(8) Turn the head lights ON.
(9) Check that the head lights light up the paper as
shown in the illustration.
(10) When the paper is not lighted up properly, adjust the
lights in the vertical or horizontal direction.
HINT:
As shown in the illustration, adjust aiming of the LH and RH
lights along each vertical line respectively.
(d) Vertical Alignment:
Adjust the headlight aimming.
(1) Using adjustment bolt A, adjust the headlight aim-
ing to within the specifiactions.
(2) Make sure the gauge bubble is within the accept-
able range.
HINT:
If the gauge bubble is outside the acceptable range, check that
the vehicle is parked on a level spot.
Readjust the headlight aiming after parking the vehicle on a lev-
el spot.

BE0H2±08
I01352
Front Fog Lights
Combination Switch

Front Fog Light Switch Driver Side Junction Block

FOG Fuse

Fog Light Relay

Body ECU No.2
BE±52
± BODY ELECTRICALFOG LIGHT SYSTEM
2353 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
FOG LIGHT 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.

BE0H0±06
I01353
Turn Signal LightsEngine Room No.1
Junction Block

TURN HAZ Fuse
Ignition Switch
Combination Switch

Turn Signal Switch
Hazard Warning Switch
Turn Signal Lights Turn Signal Lights
Driver Side Junction Block

GAUGE FuseCowl Side No.5
Junction Block

Turn Signal Flaher
± BODY ELECTRICALTURN SIGNAL AND HAZARD WARNING SYSTEM
BE±55
2356 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
TURN SIGNAL AND HAZARD WARNING 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.

BE0GY±05
I01354
Front Personal Light
Rear Personal Light
Door Courtesy Light
Licence Plate Light Luggage Compartment Light
Door Courtesy Lights
Luggage Compartment
Courtesy Switch
Door Courtesy Light
Vanity Light
Vanity Light
Rheostat Light Control
Glove Compartment
Door Courtesy Light
Glove Compartment
Door Courtesy Switch
Passenger Side Junction Block

DOME Fuse

Body ECU No.1
Driver Side Junction Block

Body ECU No.2
Luggage
Compartment
Key Lock and
Unlock Switch
Rear Personal Light Rear Personal Light
± BODY ELECTRICALINTERIOR LIGHT SYSTEM
BE±59
2360 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
INTERIOR LIGHT SYSTEM
LOCATION