2000 LEXUS GS400 Service Repair Manual

I04034
Wire Harness Side
16
I04034
Wire Harness Side
179
I04035
From Back Side
14 13 15
BE±38
± BODY ELECTRICALHEADLIGHT AND TAILLIGHT SYSTEM
2339 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
4. INSPECT LIGHT CONTROL SWITCH CIRCUIT
Connector disconnected:
(See page DI±832)
Disconnect the connector from the switch and inspect the con-
nector on the wire harness side, as shown.
Tester connectionConditionSpecified condition
16 ± GroundConstantContinuity
If circuit is not as specified, inspect the wire harness.
5. INSPECT HEADLIGHT DIMMER SWITCH CIRCUIT
Connector disconnected:
(See page DI±832)
Disconnect the connector from the switch and inspect the con-
nector on the wire harness side, as shown.
Tester connectionConditionSpecified condition
17 ± GroundConstantContinuity
9 ± GroundLight control switch HEADBattery positive voltage
If circuit is not as specified, inspect the wire harness.
6. INSPECT LIGHT CONTROL SWITCH CIRCUIT
Connector connected:
Connect the wire harness side connector to the light control and
dimmer switch and inspect the connector from the back side, as
shown.

I04035
From Back Side
8 18
± BODY ELECTRICALHEADLIGHT AND TAILLIGHT SYSTEM
BE±39
2340 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)Tester connection
ConditionSpecified condition
13 ± GroundLight control switch OFF, TAIL or HEADNo voltage
13 ± GroundLight control switch AUTOBattery positive voltage
14 ± GroundLight control switch OFF or TAILNo voltage
14 ± GroundLight control switch HEADBattery positive voltage
15 ± GroundLight control switch OFFNo voltage
15 ± GroundLight control switch TAIL or HEADBattery positive voltage
If circuit is not as specified, inspect the wire harness.
7. INSPECT HEADLIGHT DIMMER SWITCH CIRCUIT
Connector connected:
Connect the wire harness side connector to the light control and
dimmer switch and inspect the connector from the back side, as
shown.
Tester connectionConditionSpecified condition
8 ± Ground
Headlight dimmer switch FLASH
Light control switch HEAD and dimmer switch
HIGH
No voltage
8 ± GroundLight control switch HEAD and
dimmer switch LOWBattery positive voltage
18 ± GroundLight control switch HEAD and
dimmer switch LOW and fog light switch ONNo voltage
18 ± Ground
Light control switch HEAD and
dimmer switch HIGH or FLASH and fog light
switch ON
Battery positive voltage
If circuit is not as specified, inspect the wire harness.

I04036
1 2
3 41 2 3
4 5 6 Connector ºBº Connector ºAº
A2 B3 B1
A3
A5 A1 B4 B2
I01259
21
3 4
2
41
3
BE±40
± BODY ELECTRICALHEADLIGHT AND TAILLIGHT SYSTEM
2341 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
8. INSPECT DAYTIME RUNNING LIGHT NO.3 AND NO.4
RELAY CONTINUITY
Tester connectionConditionSpecified condition
A1 ± B3ConstantContinuity
A3 ± A5ConstantContinuity
B3 ± B4ConstantContinuity
A2 ± A5Apply battery positive voltage between
terminals A1 and B3.Continuity
B1 ± B2Apply battery positive voltage between
terminals B3 and B4.Continuity
If continuity is not as specified, replace the relay.
9. INSPECT HEADLIGHT CONTROL RELAY CONTINU-
ITY
ConditionTester connectionSpecified condition
Constant1 ± 2Continuity
Apply B+ between
terminals 1 and 2.3 ± 4Continuity
If continuity is not as specified, replace the relay.
10. INSPECT HEADLIGHT CONTROL RELAY CIRCUIT
(See page DI±847 and BE±21)

I01260
21
3 42
41
3
I01200
2 1
35
2 5
1 3
I04037
Wire Harness Side
h±10±1±A
± BODY ELECTRICALHEADLIGHT AND TAILLIGHT SYSTEM
BE±41
2342 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
11. INSPECT HEADLIGHT DIMMER ( DAYTIME RUNNING
LIGHT NO.2) RELAY CONTINUITY
ConditionTester connectionSpecified condition
Constant1 ± 4
2 ± 4Continuity
Apply B+ between
terminals 2 and 4.1 ± 3 ± 4Continuity
If continuity is not as specified, replace the relay.
12. INSPECT HEADLIGHT DIMMER (DAYTIME RUNNING
LIGHT NO.2) RELAY CIRCUIT
(See page BE±21)
13. INSPECT TAILLIGHT CONTROL RELAY CONTINUITY
ConditionTester connectionSpecified condition
Constant1 ± 2Continuity
Apply B+ between
terminals 1 and 2.3 ± 5Continuity
If continuity is not as specified, replace the relay.
14. INSPECT TAILLIGHT CONTROL RELAY CIRCUIT
(See page DI±845 and BE±21)
15. INSPECT DAYTIME RUNNING LIGHT MAIN RELAY
CIRCUIT
Disconnect the connector from the relay and inspect the con-
nector on the wire harness side.
Tester connectionConditionSpecified condition
2 ± GroundLight control switch OFF or TAILNo continuity
2 ± GroundLight control switch HEADContinuity
4 ± GroundParking brake switch OFF
(Parking brake pedal released)No continuity
4 ± GroundParking brake switch ON
(Parking brake pedal depressed)Continuity
6 ± GroundConstantContinuity
8 ± GroundHeadlight dimmer switch LOW beamNo continuity

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.

I01255
1
2 3 4
From Back Side BE±44
± BODY ELECTRICALHEADLIGHT AND TAILLIGHT SYSTEM
2345 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
21. INSPECT AUTOMATIC LIGHT CONTROL SENSOR
CIRCUIT
Connector connected
Connect the wire harness side connector to the sensor and in-
spect wire harness side connector from the back side, as
shown.
HINT:

Ignition switch ON.

Light control switch AUTO.

Vehicle's surroundings are bright.
Tester connectionConditionSpecified condition
3 ± GroundConstantContinuity
1 ± GroundIgnition switch LOCK or ACCNo voltage
1 ± GroundIgnition switch ON9.5 V or more
Vehicle is under the direct sun light.
(Sensor is not covered)Taillight and Headlight are ON.
If circuit is as specified, try replacing the sensor with a new one.
If the circuit is not as specified, inspect the circuit connected to
other parts.

BE0HB±04
I07736
Adjusting Bolt
(High±Beam Headlight
Horizontal Direction)Adjusting Bolt
(High±Beam Headlight
Vertical Direction)Beam Angle Gauge
(Vertical Alignment)Adjusting Bolt A
(Low±Beam Headlight
Vertical Direction)Adjusting Bolt B
(Low±Beam Headlight
Horizontal Direction)
Adjusting Bolt
(High±Beam Headlight
Horizontal Direction) Adjusting Bolt
(High±Beam Headlight
Vertical Direction) Adjusting Bolt A
(Low±Beam Headlight
Vertical Direction) Adjusting Bolt B
(Low±Beam Headlight
Horizontal Direction)
Headlight Beam Level Control Actuator Light Control ECU
Headlight Beam Level Control ECU
(Left side only)
± BODY ELECTRICALHEADLIGHT AND TAILLIGHT SYSTEM
BE±45
2346 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
ADJUSTMENT