Lexus GS300/400 (2000 year). Service manual — part 81

I04034

Wire Harness Side

16

I04034

Wire Harness Side

17

9

I04035

From Back Side

14

13

15

BE–38

–

BODY ELECTRICAL

HEADLIGHT AND TAILLIGHT SYSTEM

2339

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 connection

Condition

Specified condition

16 – Ground

Constant

Continuity

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 connection

Condition

Specified condition

17 – Ground

Constant

Continuity

9 – Ground

Light control switch HEAD

Battery 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 ELECTRICAL

HEADLIGHT AND TAILLIGHT SYSTEM

BE–39

2340

Tester connection

Condition

Specified condition

13 – Ground

Light control switch OFF, TAIL or HEAD

No voltage

13 – Ground

Light control switch AUTO

Battery positive voltage

14 – Ground

Light control switch OFF or TAIL

No voltage

14 – Ground

Light control switch HEAD

Battery positive voltage

15 – Ground

Light control switch OFF

No voltage

15 – Ground

Light control switch TAIL or HEAD

Battery 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 connection

Condition

Specified condition

8 – Ground

Headlight dimmer switch FLASH

Light control switch HEAD and dimmer switch

HIGH

No voltage

8 – Ground

Light control switch HEAD and

dimmer switch LOW

Battery positive voltage

18 – Ground

Light control switch HEAD and

dimmer switch LOW and fog light switch ON

No 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

4

1

2

3

4

5

6

Connector ”B”

Connector ”A”

A2

B3

B1

A3

A5

A1

B4

B2

I01259

2

1

3

4

2

4

1

3

BE–40

–

BODY ELECTRICAL

HEADLIGHT AND TAILLIGHT SYSTEM

2341

8.

INSPECT DAYTIME RUNNING LIGHT NO.3 AND NO.4
RELAY CONTINUITY

Tester connection

Condition

Specified condition

A1 – B3

Constant

Continuity

A3 – A5

Constant

Continuity

B3 – B4

Constant

Continuity

A2 – A5

Apply battery positive voltage between

terminals A1 and B3.

Continuity

B1 – B2

Apply 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

Condition

Tester connection

Specified condition

Constant

1 – 2

Continuity

Apply B+ between

terminals 1 and 2.

3 – 4

Continuity

If continuity is not as specified, replace the relay.
10.

INSPECT HEADLIGHT CONTROL RELAY CIRCUIT
(See page

DI–847

and

BE–21

)

I01260

2

1

3

4

2

4

1

3

I01200

2

1

3

5

2

5

1

3

I04037

Wire Harness Side

h–10–1–A

–

BODY ELECTRICAL

HEADLIGHT AND TAILLIGHT SYSTEM

BE–41

2342

11.

INSPECT HEADLIGHT DIMMER ( DAYTIME RUNNING
LIGHT NO.2) RELAY CONTINUITY

Condition

Tester connection

Specified condition

Constant

1 – 4

2 – 4

Continuity

Apply B+ between

terminals 2 and 4.

1 – 3 – 4

Continuity

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

Condition

Tester connection

Specified condition

Constant

1 – 2

Continuity

Apply B+ between

terminals 1 and 2.

3 – 5

Continuity

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 connection

Condition

Specified condition

2 – Ground

Light control switch OFF or TAIL

No continuity

2 – Ground

Light control switch HEAD

Continuity

4 – Ground

Parking brake switch OFF

(Parking brake pedal released)

No continuity

4 – Ground

Parking brake switch ON

(Parking brake pedal depressed)

Continuity

6 – Ground

Constant

Continuity

8 – Ground

Headlight dimmer switch LOW beam

No continuity