Lexus LS400 (2000 year). Service manual — part 39

N13434

–

BODY ELECTRICAL

POWER SOURCE

BE–25

1888

3.

RELAY CIRCUIT

Remove the relay from the junction block and inspect the con-
nector on junction block side.
Connect numbers are shown in the illustration.

Relay

Tester connection

Condition

Specified condition

Taillight Control

(2) – Ground

Light control switch TAIL or HEAD

Continuity

Taillight Control

(3) – Ground

Constant

Continuity

Taillight Control

(1) – Ground

Constant

Battery positive voltage

Taillight Control

(4) – Ground

Constant

Battery positive voltage

Ignition Main

(6) – Ground

Constant

Continuity

Ignition Main

(7) – Ground

Constant

Continuity

Ignition Main

(5) – Ground

Ignition switch ON

Battery positive voltage

Power Main

(12) – Ground

Constant

Battery positive voltage

Fog Light Control

(13) – Ground

Light control switch HEAD

Battery positive voltage

Fog Light Control

(16) – Ground

Constant

Battery positive voltage

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

4.

Bolted type:
FUSIBLE LINK CIRCUIT

(a)

Remove the battery.

(b)

Remove the fusible link set bolts.

(c)

Inspect the continuity between terminals and connected
parts.

(d)

Connect numbers are shown in the illustration.

Terminal

Connected parts

1

Ignition switch

2

Battery positive voltage

3

ALT–S Fuse

3

ST Fuse

3

HORN Fuse

3

HAZ Fuse

3

EFI Fuse

3

RADIO Fuse

3

TEL Fuse

3

SRS Fuse

4

Battery positive voltage

6

Battery positive voltage

6

HTR H–Fuse

6

AM1 H–Fuse

6

ABS H–Fuse

6

DEF H–Fuse

6

H/CTRL H–Fuse

6

FOG Fuse

6

STOP Fuse

6

OBD Fuse

Z14948

BE–26

–

BODY ELECTRICAL

POWER SOURCE

1889

6

FUEL OPN Fuse

6

IG1 Main Relay

7

ABS H–Fuse

8

ABS Motor Relay

8

ABS SOL Relay

9

HTR H–Fuse

10

Heater Main Relay

11

DEF H–Fuse

12

Defogger Relay

13

AM1 H–Fuse

14

Ignition switch

If circuit is not as specified, inspect wire harness between fus-
ible link and connected parts.

5.

INSPECT ENGINE ROOM JUNCTION BLOCK

–

BODY ELECTRICAL

POWER SOURCE

BE–27

1890

6.

FUSE CIRCUIT

Remove the fuse from the junction block and inspect the con-
nector on junction block side.
Connect numbers are shown in the illustration.

Fuse

Tester connection

Condition

Specified Condition

ECU–B

2 – Ground

Light control switch TAIL or HEAD

Battery positive voltage

MPX–B

4 – Ground

Constant

Battery positive voltage

RADIO NO.1

5 – Ground

Constant

Battery positive voltage

CRT

8 – Ground

Engine Running

Battery positive voltage

TEL

9 – Ground

Constant

Battery positive voltage

ALT–S

11 – Ground

Constant

Battery positive voltage

FR S/HTR

14 – Ground

Engine Running

Battery posidive voltage

MIR–HTR

16 – Ground

Ignition switch ON and Defogger switch ON

Battery positive voltage

EFI NO.2

18 – Ground

Engine Running

Battery positive voltage

H–LP R–UPR

19 – Ground

*Engine running or Light control switch HEAD

and Dimmer switch HI

Battery positive voltage

H–LP L–UPR

21 – Ground

*Engine running or Light control switch HEAD

and Dimmer switch HI

Battery positive voltage

ETCS

27 – Ground

Constant

Battery positive voltage

HORN

29 – Ground

Constant

Battery positive voltage

OBD

32 – Ground

Constant

Battery positive voltage

DOME

33 – Ground

Constant

Battery positive voltage

EFI NO.1

35 – Ground

Constant

Battery positive voltage

HAZ

38 – Ground

Constant

Battery positive voltage

Short Pin

40 – Ground

Ignition switch ACC or ON

Battery positive voltage

ST H

41 – Ground

Constant

Battery positive voltage

RDI FAN H

43 – Ground

Engine Running

Battery positive voltage

If the circuit is not as specified, inspect the circuits connected
to other parts.
7.

RELAY CIRCUIT

Remove the relay from the relay block and inspect the connec-
tor on relay block side.
Connect numbers are shown in the illustration.

Relay

Tester connection

Condition

Specified condition

Horn

(1) – Ground

Horn switch ON

Continuity

Horn

(2) – Ground

Constant

Continuity

Horn

(3) – Ground

Constant

Battery positive voltage

Starter

(4) – Ground

Ignition switch START

Battery positive voltage

Starter

(7) – Ground

Constant

Battery positive voltage

*

1

Headlight Dimmer

(8) – Ground

Constant

Continuity

*

1

Headlight Dimmer

(9) – Ground

Headlight dimmer switch HI

Continuity

*

1

Headlight Dimmer

(10) – Ground

Constant

Continuity

*

1

Headlight Dimmer

(11) – Ground

Light control switch HEAD

Battery positive voltage

*

2

Headlight Dimmer

(8) – Ground

Constant

No continuity

*

2

Headlight Dimmer

(9) – Ground

Light control switch HEAD and Headlight dimmer

switch HI

Continuity

*

2

Headlight Dimmer

(10) – Ground

Constant

Continuity

BE–28

–

BODY ELECTRICAL

POWER SOURCE

1891

*

2

Headlight Dimmer

(11) – Ground

Constant

Battery positive voltage

Headlight Control

(13) – Ground

Light control switch HEAD

Continuity

Headlight Control

(12) – Ground

Constant

Battery positive voltage

Headlight Control

(14) – Ground

Light control switch HEAD

Battery positive voltage

Headlight Control

(15) – Ground

Constant

Battery positive voltage

Engine Main

(17) – Ground

Constant

Continuity

Engine Main

(18) – Ground

Constant

Continuity

Engine Main

(20) – Ground

Constant

Battery positive voltage

Engine Main

(16) – Ground

Ignition switch ON

Battery positive voltage

Heater Main

(22) – Ground

Constant

Continuity

Heater Main

(25) – Ground

Constant

Battery positive voltage

Heater Main

(21) – Ground

Ignition switch ON

Battery positive voltage

Fuel Pump

(26) – Ground

Engine running

Battery positive voltage

Fuel Pump

(29) – Ground

Engine running

Battery positive voltage

Fuel Pump

(27) – Ground

Engine running

Continuity

Circuit Opening

(31) – Ground

Engine running

Continuity

Circuit Opening

(30) – Ground

Engine running

Battery positive voltage

EFI Main

(35) – Ground

Constant

Continuity

EFI Main

(36) – Ground

Ignition switch ON

Battery positive voltage

A/C

(39) – Ground

A/C switch ON

Continuity

A/C

(41) – Ground

Ignition switch ON

Battery positive voltage

A/C

(38) – Ground

Ignition switch ON

Battery positive voltage

Defogger

(42) – Ground

Defogger switch ON

Continuity

Defogger

(44) – Ground

Defogger switch ON

Continuity

Defogger

(43) – Ground

Ignition switch ON

Battery positive voltage

Defogger

(45) – Ground

Constant

Battery positive voltage

*

1

: USA Models

*

2

: CANADA Models

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