ECU LEXUS GS400 2000 Service Manual PDF

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.

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

BE01R±06
I01351
Headlight Beam Level Control Actuator
Height Control SensorHeadlight Beam Level Control ECU
Driver Side Junction Block

ECU±IG Fuse

GAUGE Fuse
± BODY ELECTRICALHEADLIGHT BEAM LEVEL CONTROL SYSTEM
BE±49
2350 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
HEADLIGHT BEAM LEVEL CONTROL 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.

BE0HP±02
I03440
1 2 3
4 5 6
I05442
Wire Harness Side BE±50
± BODY ELECTRICALHEADLIGHT BEAM LEVEL CONTROL SYSTEM
2351 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
INSPECTION
1. INSPECT HEADLIGHT BEAM LEVEL CONTROL AC-
TUATOR RESISTANCE
(a) Check that continuity exists between terminals 2 and 5.
(b) Check that resistance exists between terminals, as
shown in the chart.
TerminalResistance (W)
2 ± 126 ± 30
2 ± 326 ± 30
2 ± 426 ± 30
2 ± 626 ± 30
5 ± 126 ± 30
5 ± 326 ± 30
5 ± 426 ± 30
5 ± 626 ± 30
If resistance value is not as specified, replace the actuator.
2. INSPECT HEADLIGHT BEAM LEVEL CONTROL ECU
CIRCUIT
Connector disconnected:
Disconnect the connector from the ECU and inspect the con-
nector on the wire harness side, as shown.
Tester connectionConditionSpecified condition
A1 ± A5Ignition switch OFF26 ± 30 W
A1 ± A6Ignition switch OFF26 ± 30 W
A1 ± A7Ignition switch OFF26 ± 30 W
A1 ± A8Ignition switch OFF26 ± 30 W
A4 ± B4Ignition switch ON and light control switch HEADBelow 1.5 V
B1 ± B3Ignition switch OFF3.5 ± 6.5 kW
B5 ± B7Ignition switch OFF3.5 ± 6.5 kW
A4 ± GroundIgnition switch OFFContinuity
If circuit is not as specified, perform the inspection on the follow-
ing pages.

I05442
I05441
13 m sec./ DivisionMotor operating 5V
/ Division
GND Pulse generation
± BODY ELECTRICALHEADLIGHT BEAM LEVEL CONTROL SYSTEM
BE±51
2352 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
3. INSPECT HEADLIGHT BEAM LEVEL CONTROL ECU
CIRCUIT
Connector connected:
Connect the connector from the ECU and inspect the connec-
tor, as shown in the table.
Tester connectionConditionSpecified condition
A1 ± A4Ignition switch ONBattery positive voltage
A1 ± A5Ignition switch ON, when stopping and bouncing
the vehicle.Pulse generation
A1 ± A6Ignition switch ON, when stopping and bouncing
the vehicle.Pulse generation
A1 ± A7Ignition switch ON, when stopping and bouncing
the vehicle.Pulse generation
A1 ± A8Ignition switch ON, when stopping and bouncing
the vehicle.Pulse generation
B2 ± B3Ignition switch ONApprox. 2.5 V
B6 ± B7Ignition switch ONApprox. 2.5 V
B1 ± B3
B5 ± B7Ignition switch ON5 V
If the circuit is not as specified, replace the ECU.
Reference INSPECTION USING OSCILLOSCOPE
HINT:
The correct waveform is as shown in the illustration.

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.

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

I04051
Wire Harness Side
I04061
Open Close
1 2
BE±62
± BODY ELECTRICALINTERIOR LIGHT SYSTEM
2363 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
6. INSPECT VANITY LIGHT CIRCUIT
Disconnect the connector from the light and inspect the con-
nector on the wire harness side, as shown.
Tester connectionConditionSpecified condition
2 ± GroundConstantContinuity
1 ± GroundConstantBattery positive voltage
If circuit is not as specified, inspect power source or wire har-
ness.
7. Front door:
INSPECT DOOR COURTESY SWITCH CONTINUITY
(a) Connect the connector to the front door ECU.
(b) Check that continuity exists between terminals 1 and 2
when door is opened.
(c) Check that no continuity exists between terminals 1 and
2 when door is closed.
If continuity is not as specified, replace the switch.
8. Front door:
INSPECT DOOR COURTESY SWITCH CIRCUIT
Driver side: (See page DI±868)
Passenger side: (See page DI±900)

I04066
Open Close
1 2
I04052e±2±2±J
21
I04053
Wire Harness Side
I04054
1 2
± BODY ELECTRICALINTERIOR LIGHT SYSTEM
BE±63
2364 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
9. Rear door:
INSPECT DOOR COURTESY SWITCH CONTINUITY
(a) Connect the connector to the rear door ECU.
(b) Check that continuity exists between terminals 1 and 2
when door is opened.
(c) Check that no continuity exists between terminals 1 and
2 when door is closed.
If continuity is not as specified, replace the switch.
10. Rear door:
INSPECT DOOR COURTESY SWITCH CIRCUIT
Rear LH side: (See page DI±930)
Rear RH side: (See page DI±947)
11. INSPECT DOOR COURTESY LIGHT CONTINUITY
Using an ohmmeter, check that continuity exists between termi-
nals.
If continuity is not as specified, replace the light assembly or
bulb.
12. INSPECT DOOR COURTESY LIGHT CIRCUIT
Driver side: (See page DI±874)
Passenger side: (See page DI±906)
Rear LH side: (See page DI±934)
Rear RH side: (See page DI±951)
13. INSPECT LUGGAGE COMPARTMENT DOOR COUR-
TESY SWITCH CONTINUITY
Switch positionTester connectionSpecified condition
OFF (closed)±No continuity
ON (opened)2 ± Switch bodyContinuity
If continuity is not as specified, replace the switch.

BE0HH±07
I01359
Brake Master Cylinder

Brake Fluid Level
Warning Switch
Combination Meter
and Telltale Light
Assembly
Airbag Sensor Assembly Parking Brake Switch
Driver Side
Junction Block

GAUGE Fuse

SRS±B FuseIgnition Switch
ECM
Washer Tank

Washer Level
Warning Switch Engine Room No.1
Junction Block

MPX±B Fuse
Seat Belt Buckle Switch
Rheostat Light Control
ABS, TRAC and VSC ECU
Clock Assembly

Passenger Seat Belt
Waning Light
BE±80
± BODY ELECTRICALCOMBINATION METER
2381 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
COMBINATION METER
LOCATION
The vehicle shown in this illustration is ºGS400º.
All components of ºGS300º other than the ones used for engine are same as ºGS400º.