Lexus SC300 / Lexus SC400. Manual - part 212

(Integration Relay)

REMOVAL AND INSTALLATION OF
INTEGRATION RELAY

(See page 

BE–16

)

INSPECTION OF INTEGRATION RELAY

INSPECT INTEGRATION RELAY

(Relay Circuit/Light Auto Turn Off System)
Remove the relay from junction block and inspect the con-
nectors on the wire harness and junction block side as shown
in the chart.

(USA)

Check for

Tester connection

Condition

Specified value

Continuity

A4–Ground

Passenger’s Courtesy

OFF

No continuity

y

g

y

ON

Continuity

A5–Ground

Ignition Key

Pull off

No continuity

g

y

Put in

Continuity

A6–Ground

Driver’s Courtesy

OFF

No continuity

y

ON

Continuity

A8–Ground

Seat Belt

Unfasten

Continuity

Fasten

No continuity

A10–Ground

Constant

Continuity

B1–Ground

Passenger’s Door

Unlock

Continuity

g

Lock

No continuity

B2–Ground

Driver’s Door

Unlock

Continuity

Lock

No continuity

B3–Ground

Light Control Switch

OFF

No continuity

g

TAIL or HEAD

Continuity

B6–Ground

Light Control Switch

TAIL or OFF

No continuity

g

HEAD

Continuity

Voltage

A1–Ground

Constant

Voltage

g

A2–Ground

Constant

*Voltage

A7–Ground

Ignition Switch

ON

Voltage

g

LOCK or ACC

No voltage

A9–Ground

Ignition Switch

ON

Battery voltage

g

LOCK or ACC

No voltage

A11–Ground

Ignition Switch

ON or ACC

Voltage

g

LOCK

No voltage

* There is resistance because this circuit is grounded through the bulb.

–

BODY ELECTRICAL SYSTEM

Light System

BE–49

(Canada)

Check for

Tester connection

Condition

Specified value

Continuity

A4–Ground

Passenger’s Courtesy

OFF

No continuity

y

g

y

ON

Continuity

A5–Ground

Ignition Key

Pull off

No continuity

g

y

Put in

Continuity

A6–Ground

Driver’s Courtesy

OFF

No continuity

y

ON

Continuity

A8–Ground

Seat Belt

Unfasten

Continuity

Fasten

No continuity

A10–Ground

Constant

Continuity

A12–Ground

Constant

Continuity

B1–Ground

Passenger’s Door

Unlock

Continuity

g

Lock

No continuity

B2–Ground

Parking Brake
Switch Position

OFF (Switch pin
pushed in)

No continuity

ON (Switch pin re-
leased)

Continuity

B3–Ground

Driver’s Door

Unlock

Continuity

Lock

No continuity

B7–Ground

Headlight Dimmer
Switch Position

Low Beam or High
Beam

No continuity

Flash

Continuity

B8–Ground

Headlight Dimmer

Low Beam

No continuity

g

Switch Position

High Beam or Flash

Continuity

B10–Ground

Light Control Switch

OFF

No continuity

g

HEAD or TAIL

Continuity

B12–Ground

Constant

Continuity

B13–Ground

Light Control Switch

OFF or TAIL

No continuity

g

HEAD

Continuity

Voltage

A1–Ground

Constant

Voltage

g

A2–Ground

Constant

*Voltage

A7–Ground

Ignition Switch

ON

Voltage

g

LOCK or ACC

No voltage

A9–Ground

Ignition Switch

ON

*Voltage

g

LOCK or ACC

No voltage

A11–Ground

Ignition Switch

ON or ACC

Voltage

g

LOCK

No voltage

B4–Ground

Engine

STOP

No voltage

g

Running

Voltage

B11–Ground

Constant

Voltage

* There is resistance because this circuit is grounded through the bulb.

If the circuit is as specified, trying replacing the relay with a
new one.
If the circuit is not as specified, refer to 

BE–35

 wiring diagram

and inspect the circuit connected to other parts.

BE–50

–

BODY ELECTRICAL SYSTEM

Light System

DEFOGGER SYSTEM

Description

The component parts of this system and their functions are described in the following table.

ÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑ

Parts Name

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

Function

ÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑ

Defogger

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

When over current flows in the defogger circuit, the Defogger fuse breaks the circuit to pro-
tect it against damage.

ÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑ

Defogger Relay

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

This relay is supplied with current from terminal IG1 of ignition switch (Ignition switch
ON) and switches large current from the defogger.

ÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑ

A/C Control Panel
Assembly



 Defogger Switch

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

The defogger switch is built into the A/C Control Panel Assembly. This switch is
supplied with current from the relay and fuse HTR. Grounds current from the defogger
relay, turning the defogger relay ON.

ÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑ

Defogger



 Rear Window



 Outer Mirror

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

These defoggers generate heat when current is supplied from the defogger relay.

Parts Location

–

BODY ELECTRICAL SYSTEM

Lighting System

BE–51

Wiring and Connector Diagrams

Parts Inspection
(Defogger Switch)

REMOVAL AND INSTALLATION OF AIR
CONDITIONER CONTROL PANEL
ASSEMBLY

(See Instrument Panel on Pub. No. RM260U2, page 

BO–111

)

INSPECTION OF DEFOGGER SWITCH

INSPECT SWITCH OPERATION

(a)  Connect the positive (+) lead from the battery to terminal A6

and negative (–) lead to terminal A7.

(b) Connect 

the 

positive (+) lead from the battery to terminal B10

through a 1.4 W test bulb.

BE–52

–

BODY ELECTRICAL SYSTEM

Defogger System