Lexus RX300 (MCU15). Service manual - part 339

I12718

Front Interior
Light

Body ECU

B7

ILE

10

Key Cylinder
Light

C

J/B No.5

R–W

R–Y

1

1

5C

J4

ON

2

2

R

R

R

W

5

ID1

DOOR

3

9

OFF

2A

2I

Junction
Connector

Short Pin

2

R

DOME

Engine Room J/B

Battery

J4

C

R

5B

5B

8

6

ID1

3

R–W

R–W

5F

5F

6

J/B No.5

5B

1

2

1

3

F11
FL BLOCK

W

DI–588

–

DIAGNOSTICS

BODY CONTROL SYSTEM

LEXUS RX300   (RM785E)

Illumination circuit

CIRCUIT DESCRIPTION

Receiving the courtesy signal from either of the door ECU, the Body ECU will make the front interior light
and ignition light, come on.

WIRING DIAGRAM

DI1OW–10

–

DIAGNOSTICS

BODY CONTROL SYSTEM

DI–589

LEXUS RX300   (RM785E)

INSPECTION PROCEDURE

HINT:
In case of using the hand–held tester, start the inspection from step 1 and in case of not using the hand–held
tester, start from step 2.

1

Check illumination (interior light, ignition switch light) using hand–held tester.

PREPARATION:
Connect the hand–held tester to the DLC 3.
CHECK:
Check that the illumination can light in an ACTIVE TEST.
OK:
All the illumination should light on.

OK

Proceed to next circuit inspection shown on
problem symptoms table (See page DI–570).

NG

2

Check illumination light.

NG

Replace the failure light.

OK

3

Check wireharness and connector between each illumination light and Body
ECU, battery and each illumination light .

NG

Repair or replace wireharness or connector.

OK

Proceed to next circuit inspection shown on
problem symptoms table
(See page DI–570).

I07435

Body ECU

B7

W–B

KSW

W–B

8

L

IF

Key Unlock
Warning Switch

J7
Junction
Connector

A

A

2

1

DI–590

–

DIAGNOSTICS

BODY CONTROL SYSTEM

LEXUS RX300   (RM785E)

Key unlock warning switch circuit

CIRCUIT DESCRIPTION

The key unlock warning switch goes on when the ignition key is inserted in the key cylinder and goes off when
the ignition key is removed. 
The ECU operates the key confinement prevention function while the key unlock warning switch is on.

WIRING DIAGRAM

DI1OX–12

–

DIAGNOSTICS

BODY CONTROL SYSTEM

DI–591

LEXUS RX300   (RM785E)

INSPECTION PROCEDURE

1

Check key unlock warning switch (See page BE–26).

NG

Replace the key unlock warning switch.

OK

2

Check wireharness and connector between key unlock warning switch and Body
ECU.

NG

Repair or replace wireharness or connector.

OK

Proceed to next circuit inspection shown on
problem symptoms table
(See page DI–570).