Lexus LS400 (2000 year). Manual - part 58

Z08740

Wire Harness Side

BE–60

–

BODY ELECTRICAL

TURN SIGNAL AND HAZARD WARNING SYSTEM

1923

3.

INSPECT HAZARD WARNING SWITCH CIRCUIT

Disconnect the switch connector and inspect the connection on
the wire harness side, as shown.

Tester connection

Condition

Specified condition

8 – Ground

Constant

Continuity

*2 – Ground

Light control switch position OFF

No voltage

*2 – Ground

Light control switch position TAIL or HEAD

Battery positive voltage

*: illumination
If the circuit is not as specified, inspect the circuits connected
to other parts.

BE0BO–01

I03234

Auto Light Control Sensor

Rheostat Light Control

Body ECU

Instrument Panel
Junction Block

 PANEL Fuse

 GAUGE Fuse

 TAIL Relay

Combination Switch

 Light Control Switch

Glove Box Light 
Switch

–

BODY ELECTRICAL

ILLUMINATION LIGHT SYSTEM

BE–61

1924

ILLUMINATION LIGHT SYSTEM

LOCATION

BE0BP–01

I03417

Rheostat Light Control

Automatic Light Control Sensor

Wire Harness Side

Front Back Side

Wire Harness Side

BE–62

–

BODY ELECTRICAL

ILLUMINATION LIGHT SYSTEM

1925

CIRCUIT

1.

When checking voltage, resistance, etc., use a high impedance type tester (It is impossible with
a simple tester).

2.

When the ignition switch is turned to START, all meters will go out but this is normal.

3.

When replacing the internal mechanism (computer parts) of the meter, be careful that no part
of your body or clothing comes in contact with the terminals of the leads from the IC, etc. of the
replacement parts (spare parts).

4.

Do not disconnect the battery while the engine is running as this would cause an instant reverse
charge, resulting in damage to the components.

5.

Always disconnect the battery terminals before pulling apart connectors or terminals.

6.

To prevent damage, handle meters with care.

No.

Trouble

1

None of the illuminations can be adjusted.

2

Only the combination meter cannot be adjusted.

3

The combination meter can be adjusted, but not other illumination.

4

Tail cancellation does not work for the clock, air conditioner panel

and combination meter.

5

Tail cancellation does not work for one of clock,

air conditioner panel or combination meter.

6

Tail cancellation (illumination at 100 % brightness) does not occur when tail can-

cellation of the rheostat light control is released, the light control switch is put on

AUTO and light strikes the automatic light control sensor.

(Area surrounding vehicle is dark)

HINT:
Tail cancellation refers to the illumination brightness becoming 100 % when the rheostat light control is
turned to the right beyond the moderate position. (Light is not applied to the automatic light control sensor
at this time.)

I03249

1

None of the illuminations can be adjusted

HINT: While carrying, out the following inspection, make certain that the connectors and terminals are properly con-
nected.

Connect the wire harness side connector to the
rheostat light control and inspect wire harness
side connector from the back side, as shown.

Ignition switch position ON.

No

Replace GAUGE Fuse.
Then recheck system.

Yes

Turn light control switch to TAIL.
Taillight is normal?

No

Taillight system faulty. Inspect taillight circuit.
(See page 

BE–23

)

Then recheck system.

Yes

With light control switch at TAIL, Connect the

Is there battery positive voltage?

Replace PANEL Fuse.
Then recheck system.

No

Yes

Automatic light control system is normal?
(See page 

BE–38

)

Yes

Automatic light control system faulty.
Replace automatic light control sensor.
Then recheck system.

No

Disconnect connectors from rheostat light
control and automatic light control sensor,
then inspect wire harness side connector.

of automatic light control sensor?

Connect the positive (+) lead from the voltmeter
to terminal 5 and negative (–) lead to the body
ground. Is there battery positive voltage?

positive (+) lead from the voltage to terminal 6
and negative (–) lead to the body ground.

Is there continuity when an ohmmeter is
connected to connector terminal 1 on the wire
harness side of the rheostat light control and
connector terminal 8 on the wire harness side

No

Replace wire harness between connector
terminal 1 rheostat side and connector
terminal 8 on sensor side.

Yes

Yes

No

Is there continuity when and ohmmeter is

connected to connector terminal 10 on wire
harness side of rheostat light control and

connector terminal 4 on wire harness side of

automatic light control sensor?

Replace wire harness between connector
terminal 10 on rheostat side and connector
terminal 8 on sensor side.

CONTINUED ON NEXT PAGE

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BODY ELECTRICAL

ILLUMINATION LIGHT SYSTEM

BE–63

1926