Lexus RX300 (MCU15). Manual - part 263

F13432

Skid Control ECU

Battery

B–Y

AM1

6

1D

4

A

VSCW

IG

7

13

10

W–B

4

2

B–R

A22

8

A23

IG1

GND3

1C

1K

Ignition Switch

HEATER

ECU–IG

J9
Junction
connector

W–G(*2)

W–B

IF1

3

C11

5

R–W

VSC Warning Light

Combination Meter

IG1 AM1

A22

1

C12

W–G(*2)

IJ1

6

W–G(*1)

W–G(*1)

W–L

J/B No. 3

1

3A

3E

5

R–W

6

1C

1

1A

1

2

J/B No. 5

5B

11

5D

1

W–B

5

3

Fusible 
Link
Block
ALT

II1

7

W

W

*1 : LHD
*2 : RHD

Instrument Panel J/B

Instrument Panel J/B

IF

17

6

GND1

31

A22

A21

A21

GND2

GND4

W–B

W–B

W–B

W–B

DI–284

–

DIAGNOSTICS

ABS & BA & TRC & VSC SYSTEM

LEXUS RX300   (RM785E)

DTC

Always ON*

Malfunction in ECU
VSC Warning Light Circuit

*: VSC warning light

CIRCUIT DESCRIPTION

DTC No.

DTC Detecting Condition

Trouble Area

Always ON

S There is a malfunction in the ECU internal circuit.

S Malfunction in power sauce circuit.

S Power source circuit

S VSC warning light circuit

S Charging system

S Skid control ECU

HINT:
If the fail safe function is activated in VSC system, ”VSC” indicator light lights up.

WIRING DIAGRAM

DI1H8–06

–

DIAGNOSTICS

ABS & BA & TRC & VSC SYSTEM

DI–285

LEXUS RX300   (RM785E)

INSPECTION PROCEDURE

1

Is DTC output for VSC?

Check DTC on page DI–205.

YES

Repair circuit indicated by the output code.

NO

2

Does VSC warning light go off?

YES

Check for open or short circuit in harness and
connector between ECU–IG fuse and ECU
(See page IN–32).

NO

3

Check battery voltage.

CHECK:
Check the battery voltage.
OK:

Voltage: 10 – 16 V

NG

Check and repair the charging system (See
page CH–2).

OK

DI–286

–

DIAGNOSTICS

ABS & BA & TRC & VSC SYSTEM

LEXUS RX300   (RM785E)

4

Check operation of the VSC warning light.

In case of using the hand–held tester:
PREPARATION:
(a)

Connect the hand–held tester to the DLC3.

(b)

Turn the ignition switch ON, and push the hand–held tester main switch ON.

(c)

Select the ACTIVE TEST mode on the hand–held tester.

CHECK:
Check that ”ON” and ”OFF” of the VSC warning light can be shown on the combination meter on the hand–
held tester.

In case of not using the hand–held tester:
PREPARATION:
(a)

Turn the ignition switch OFF.

(b)

Disconnect the connector from the skid control ECU.

(c)

Turn the ignition switch ON.

CHECK:
Check the VSC warning light goes off.

OK

Check and replace skid control ECU.

NG

Check for short circuit in harness and connector between combination meter and skid control
ECU, combination meter and DLC3 (See page IN–32).

F13433

Skid Control ECU

WA

13

IE2

ABS

6

C10

21

B–Y

6

Instrument
Panel J/B

GND1

II1

31

17

3A

1K

8

1

2

AM1

IG1

1

IF

Battery

W–B

1

2

W–B

R–W

3E

5

R–W

1

C12

B–Y

5

A23

HEATER

7

AM1

4

B–Y

W–L

Ignition
Switch

J/B No.5

A22

A22

A21

A21

GND2

GND3

GND4

W–B

W–B

W–B

W–B

W–B

W–B

7

J9
J/C

1

11

5B

5D

1C

1A

1C

W

5

3

W

A

IG

6

Fusible 
Link
Block
ALT

J/B No.3

Combination Meter

–

DIAGNOSTICS

ABS & BA & TRC & VSC SYSTEM

DI–287

LEXUS RX300   (RM785E)

ABS Warning Light Circuit

CIRCUIT DESCRIPTION

If the ECU detects trouble, it lights the ABS warning light while at the same time prohibiting ABS control. At
this time, the ECU records a DTC in memory.
Connect terminals Tc and CG of the DLC3 to make the ABS warning light blink and output the DTC.

WIRING DIAGRAM

DI6MN–05