Lexus SC300 / Lexus SC400. Manual - part 204

REPLACEMENT OF RELAY BLOCK NO. 2
(B) IN RELAY BLOCK NO. 2

1. 

REMOVE RELAY BLOCK NO. 2 (B)

(a)  Disconnect the battery terminals.

CAUTION: Work must be started after approx. 20 se-
conds or longer from the time the ignition switch is
turned to the ”LOCK” position and negative (–) terminal
cable is disconnected from the battery.

(b)  Remove the relay block No. 2 cover.
(c)  Remove the relay block No. 2 lower cover.

2. 

INSTALL RELAY BLOCK NO. 2 (B)
For installation follow the removal procedure in reverse.

–

BODY ELECTRICAL SYSTEM

Power Source

BE–17

Description

The power source supplies power to each of the vehicle’s electrical devices. It is composed of the battery, fuses
and relays, which are located centrally at relay block No. 2 and relay block No. 6 in the engine compartment
and junction block No. 1 relay block No. 4 and relay block No. 5 in the cabin near the driver’s feet.

Related systems for each Fuse

No.

Part Name

Related Systems or Parts

1

IGN

 

 Charging System

 

 AIR–BAG System

1

IGN

 

 Engine

2

ST

 

 Starter

3

WIPER

 

 Wiper and Washer System

4

HTR

 

 Defogger System

 

 A/C System

5

ENGINE

 

 Charging System

6

RADIO NO. 2

 

 Audio System

 

 Power Mirror System

 

 Cigarette Lighter

 

 A/C System

7

CIG

 

 Combination Meter System

 

 AIR–BAG System

7

CIG

 

 Shift Lock System

 

 Theft Deterrent System

 

 TEL System

8

STOP

 

 Stop Light System

 

 Cruise Control System

9

TURN

 

 Turn Signal and Hazard

   Warning Light System

 

 Cornnering Light System

10

MIR HTR

 

 Mirror Heater System

11

PANEL

 

 Illumination Light System

12

ECU–B

 

 Combination Meter System

 

 AIR–BAG System

 

 Combination Meter System

 

 ECT System

13

GAUGE

 

 Back–Up Light

 

 Transmission Indicator

 

 Light Failare Sensor

 

 ABS and TRAC

 

 Power Seat System

 

 Door Lock Control System

 

 TEL System

 

 Shift Lock System

14

ECU–IG

 

 Radiator Fan

 

 Auto Antenna

 

 Electric Tension Reducer System

 

 Power Steering

 

 Auto–Tilt away Steering

 

 Cruise Control System

15

TAIL

 

 Taillight System

 

 Side Marker

15

TAIL

 

 Clearance Light

16

DOOR

 

 Power Seat System

 

 Luggage Door Opener

16

DOOR

 

 Door Lock Control System

 

 Fuel Lid Opener System

17

IG SW

Upstream of ECU–IG, ENGINE, WIP, HTR, TURN, GAUGE, and ST Fuse

18

PWR

 

 Power Window System

 

 Sliding Roof System

19

ABS NO. 1

 

 ABS and TRAC

20

AM1

Upstream of MIR HTR, TAIL, PANEL, STOP, ECUA–B, DOOR and PWR Fuse

21

ALT

Upstream of DEF, HTR, AM1, and ABS No. 1 Fuse

BE–18

–

BODY ELECTRICAL SYSTEM

Power Source

No.

Part Name

Related Systems or Parts

22

MAIN

 

 Upstream of ALT–S and EFI Fuse

23

AM2

 

 Charging System

 

 Engine

23

AM2

 

 AIR–BAG System

24

ABS NO. 2

 

 ABS and TRAC

25

INJ

 

 Charging System

 

  Engine

25

INJ

 

 AIR–BAG System

26

DEF

 

 Defogger System

 

 Power Seat System

 

 Sliding Roof System

 

 A/C System

 

 Liquid Crystal Inner Mirror System

27

DOME

 

 Combination Meter System

 

 Interior Light System

27

DOME

 

 ABS and TRAC

 

 Wireless Door Lock Control System

 

 Cruise Control System

 

 Auto–Tilt away Steering

 

 Theft Deterrent System

28

EFI

 

 Engine

29

HAZ HORN

 

 Turn Signal and Hazard Warning Light System

29

HAZ–HORN

 

 Horn System

30

RADIO NO. 1

 

 Audio System

31

TEL

 

 TEL System

32

ALT–S

 

 Charging System

33

TRAC

 

 ABS and TRAC

34

HEAD (RH–LWR)

 

 Headlight System

35

HEAD (LH–LWR)

 

 Headlight System

36

HEAD (RH–UPR)

 

 Headlight System

37

HEAD (LH–UPR)

 

 Headlight System

38

HTR

 

 Blow Motor

–

BODY ELECTRICAL SYSTEM

Power Source

BE–19

Inspection of Power Source Circuit

INSPECTION OF JUNCTION BLOCK NO. 1

1. 

INSPECT FUSE CIRCUIT
Remove the fuse from the junction block and inspect the con-
nector on junction block side as shown.

Fuse

Check for

Tester connection

Condition

Specified value

IGN

Voltage

1–Ground

Ignition switch turned to ON

Battery voltage

ST

g

4–Ground

Ignition switch turned to START

y

g

WIPER

5–Ground

Ignition switch turned to ON

HTR

8–Ground

g

ENGINE

9–Ground

RADIO NO. 2

11–Ground

Ignition switch turned to ACC or ON

CIG

14–Ground

g

STOP

15–Ground

Constant

TURN

18–Ground

Ignition switch turned to ON

MIR HTR

20–Ground

Ignition switch turned to ON and defogger
switch turned to ON

PANEL

21–Ground

Light control switch turned to TAIL or HEAD
and *Engine Running

ECU–B

27–Ground

Constant

GAUGE

29–Ground

Ignition switch turned to ON

ECU–IG

32–Ground

g

TAIL

33–Ground

Light control switch turned to TAIL or HEAD
and *Engine Running

DOOR

35–Ground

Constant

IG SW

38–Ground

POWER

39–Ground

If the circuit is not as specified, refer to 

BE–15

 wiring diagram

and inspect the circuits connected to other parts.

BE–20

–

BODY ELECTRICAL SYSTEM

Power Source