Lexus SC300 / Lexus SC400. Service manual — part 982

1

C 1 5

H 5 , H 6

B L AC K

X

X

X

X

1 4

X

X

111

HORN

2

5

IE1

9

4

4

4

IE1

8

14

1

1

E 2

FROM POWER SOURCE SYSTEM (SEE PAGE 56)

W

W

25A
HAZ–HORN

HORN
RELAY

B

B

B

G–

R

B

1

2

6

HORN

HORN SW
[COMB. SW]

RH

LH

H 5

H 6

C15

3

HORN RELAY

2–3 : CLOSED WITH HORN SW ON

: PARTS LOCATION

CODE

SEE PAGE

CODE

SEE PAGE

CODE

SEE PAGE

C15

28

H 5

26

H 6

26

: RELAY BLOCKS

CODE

SEE PAGE

RELAY BLOCKS (RELAY BLOCK LOCATION)

2

19

ENGINE COMPARTMENT LEFT

4

23

LEFT KICK PANEL (J/B NO.1 LEFT)

: CONNECTOR JOINING WIRE HARNESS AND WIRE HARNESS

CODE

SEE PAGE

JOINING WIRE HARNESS AND WIRE HARNESS (CONNECTOR LOCATION)

IE1

36

ENGINE ROOM MAIN WIRE AND COWL WIRE (R/B NO.4)

: SPLICE POINTS

CODE

SEE PAGE

WIRE HARNESS WITH SPLICE POINTS

CODE

SEE PAGE

WIRE HARNESS WITH SPLICE POINTS

E 2

34

ENGINE ROOM MAIN WIRE

SERVICE HINTS

3

HOW TO USE THIS MANUAL

This manual provides information on the electrical circuits in on vehicles by dividing
them into a circuit for each system.

The actual wiring of each system circuit is shown from the point where the power source
is received from the battery as far as each ground point. (All circuit diagrams are shown
with the switches in the OFF position.)

When troubleshooting any problem, first understand the operation of the circuit where
the problem was detected (see System Circuit section), the power source supplying
power to that circuit (see Power Source section), and the ground points (see Ground
Points section). See the System Outline to understand the circuit operation.

When the circuit operation is understood, begin troubleshooting of the problem circuit
to isolate the cause. Use Relay Location and Electrical Routing sections to find each
part, junction block and wiring harness connectors, wiring harness and wiring harness
connectors, splice points, and ground points of each system circuit. Internal wiring for
each junction block is also provided for better understanding of connection within a
junction block.
Wiring related to each system is indicated in each system circuit by arrows (from
, to ). When overall connections are required, see the Overall Wiring Diagram
at the end of this manual.

* The system shown here is an EXAMPLE ONLY. It is different to the

actual circuit shown in the SYSTEM CIRCUITS SECTION.

4

HOW TO USE THIS MANUAL

A

B

C

D

E

F

G

H

I

J

K

L

M

N

O

P

5

: System Title

: Indicates a Relay Block. No shading is used and only

the Relay Block No. is shown to distinguish it from the
J/B.

Example:

Indicates Relay Block No. 1.

: Indicates the connector to be connected to a part (the

numeral indicates the pin No.)

Explanation of pin use.

The pins shown are only for the highest grade, or only
include those in the specification.

: Connector Color

Connectors not indicated are milky white in color.

: (

) is used to indicate different wiring and connector,

etc. when the vehicle model, engine type, or
specification is different.

: Indicates related system.

: Indicates the wiring harness and wiring harness

connector. The wiring harness with male terminal is
shown with arrows (

).

Outside numerals are pin numbers.

The first letter of the code for each wiring harness and
wiring harness connector(s) indicates the component’s
location, e.g., “E” for the Engine Compartment, “I” for the
Instrument Panel and Surrounding area, and “B” for the
Body and Surrounding area.

When more than one code has the first and second
letters in common, followed by numbers (e.g., IH1, IH2),
this indicates the same type of wiring harness and
wiring harness connector.

: Represents a part (all parts are shown in sky blue). The

code is the same as the code used in parts position.

: Junction Block (The number in the circle is the J/B No.

and the connector code is shown beside it). Junction
Blocks are shaded to clearly separate them from other
parts (different junction blocks are shaded differently for
further clarification).

3B indicates
that it is inside
Junction Block
No. 3.

Example:

: Indicates the wiring color.

Wire colors are indicated by an alphabetical code.

B

= Black

L

= Blue

R

= Red

BR

= Brown

LG = Light Green

V

= Violet

G

= Green

O

= Orange

W = White

GR = Gray

P

= Pink

Y

= Yellow

The first letter indicates the basic wire color and the
second letter indicates the color of the stripe.

Example:

L – Y

(Blue) (Yellow)

: Indicates a wiring Splice Point (Codes are “E” for the

Engine Room, “I” for the Instrument Panel, and “B” for
the Body).

Example:

The Location of Splice Point I 5 is indicated by the
shaded section.

: Page No.

: Indicates a shielded cable.

: Indicates a ground point.

The first letter of the code for each ground point(s)
indicates the component’s location, e.g., “E” for the
Engine Compartment, “I” for the Instrument Panel and
Surrounding area, and “B” for the Body and
Surrounding area.

: Indicates the pin number of the connector.

The numbering system is different for female and male
connectors.

Example:

Numbered in order
from upper left to
lower right

Numbered in order
from upper right to
lower left

: When 2 parts both use one connector in common, the

parts connector name used in the wire routing section
is shown in square brackets [

].