Lexus ES300 (2002 year). Manual - part 311

B-G

F41991

Skid Control ECU

Combination Meter

1

WA

S7

Passenger Side J/B

ABS

R-B

86

57

96

40

C7

6

3A

C7

3A

3B

3B

87

W

Driver Side J/B

From
Ignition SW

B-Y

IG1 Relay

2

8

2E

2A

IA

5

1

1

8

From Battery

2

GAUGE1

2M

2R

W-B

W

W

W

3

-

DIAGNOSTICS

ABS WITH EBD & BA & TRAC & VSC SYSTEM

05-363

516

2002 LEXUS ES300 REPAIR MANUAL   (RM911U)

DTC

AlwaysON MALFUNCTION IN ABS ECU

CIRCUIT DESCRIPTION

DTC No.

DTC Detecting Condition

Trouble Area

Always ON

Either of the following 1., 2. or 3. is detected:

1. Voltage of ECU terminal IG1 remains at more than 17 V.

2. The ECU connectors are off from the ECU.

3. There is a malfunction in the ECU internal circuit.

Battery

Charging system

Power source circuit

Skid control ECU

HINT:
There is a case that hand-held tester cannot be used when ECU is abnormal.

WIRING DIAGRAM

INSPECTION PROCEDURE

1

CHECK SKID CONTROL ECU CONNECTOR SECURELY CONNECTED

NG

CONNECT CONNECTORS

OK

2

RECONFIRM DTC(See page 

05-288

)

A

Normal Code

B

Malfunction Code

B

REPAIR CIRCUIT INDICATED BY OUTPUT
CODE

A

0529X-03

GND4

F40456

GND1

GND2

GND3

IG1

05-364

-

DIAGNOSTICS

ABS WITH EBD & BA & TRAC & VSC SYSTEM

517

2002 LEXUS ES300 REPAIR MANUAL   (RM911U)

3

CHECK VOLTAGE OF ECU IG POWER SOURCE

IN CASE OF USING THE HAND-HELD TESTER:
(a)

Select the item ”IG VOLTAGE” in the DATA LIST and red its value displayed on the hand-held tester.

(b)

Check the voltage condition output from the ECU displayed on the hand-held tester.
OK: ”Normal” is displayed.

IN CASE OF NOT USING THE HAND-HELD TESTER:
(a)

Remove the skid control ECU with connectors still con-
nected.

(b)

Turn the ignition switch ON, measure voltage between
terminals IG1 and GND of skid control ECU connector.
OK: 10 - 14 V

OK

CHECK AND REPAIR HARNESS AND
CONNECTOR

NG

4

INSPECT BATTERY(TERMINAL VOLTAGE)

(a)

Check the battery positive voltage.
OK: 10 - 14 V

NG

CHECK AND REPLACE CHARGING SYSTEM

OK

5

CHECK HARNESS AND CONNECTOR(BATTERY - SKID CONTROL ECU ASSY)

NG

CHECK AND REPAIR HARNESS AND
CONNECTOR

OK

-

DIAGNOSTICS

ABS WITH EBD & BA & TRAC & VSC SYSTEM

05-365

518

2002 LEXUS ES300 REPAIR MANUAL   (RM911U)

6

CHECK ABS WARNING LIGHT

IN CASE OF USING THE HAND-HELD TESTER:
(a)

Select the item ”ABS WARN LIGHT” in the ACTIVE TEST and operate the ABS warning light on the
hand-held tester.

(b)

Check that ”ON” and ”OFF” of the ABS warning light can be shown on the combination meter by the
hand-held tester.

IN CASE OF NOT USING THE HAND-HELD TESTER:
(a)

Turn the ignition switch OFF and disconnect the connector from the skid control ECU.

(b)

Turn the ignition switch ON.

(c)

Check the ABS warning light turns off.

OK

CHECK AND REPLACE COMPUTER ASSY,
SKID CONTROL

NG

CHECK AND REPLACE METER ASSY, COMBINATION

F41992

Skid Control ECU

Combination Meter

14

VSCW

S7

Engine Room J/B

Driver Side J/B

From
Ignition SW

R-L

B-R

B-O

IG2

8

5

2O

8

2G

1C

C8

13

7

1C

C7

39

W

B-O

VSC

IF6

8

B-R

05-366

-

DIAGNOSTICS

ABS WITH EBD & BA & TRAC & VSC SYSTEM

519

2002 LEXUS ES300 REPAIR MANUAL   (RM911U)

DTC

AlwaysON MALFUNCTION IN ECU(VSC WARNING

LIGHT)

CIRCUIT DESCRIPTION

If the ECU stores DTC, the VSC warning light lights on the combination meter.

DTC No.

DTC Detecting Condition

Trouble Area

Always ON

Malfunction in skid control EU

Battery

IC regulator

Power source circuit

Skid control  ECU

WIRING DIAGRAM

INSPECTION PROCEDURE

1

RECONFIRM DTC(See page 

05-288

)

A

Normal Code

B

Malfunction Code

B

REPAIR CIRCUIT INDICATED BY OUTPUT
CODE

A

2

CHECK VSC WARNING LIGHT

(a)

Check VSC warning light go off.

YES

CHECK AND REPAIR HARNESS AND
CONNECTOR

NO

055W3-02