Lexus ES300 (2002 year). Manual - part 285

F13041

STP

(+)

(-)

-

DIAGNOSTICS

ABS WITH EBD SYSTEM

05-269

422

2002 LEXUS ES300 REPAIR MANUAL   (RM911U)

INSPECTION PROCEDURE

1

CHECK OPERATION OF STOP LIGHT

(a)

Check that stop light turns ON when the brake pedal is depressed and turns OFF when the brake pedal
is released.

NG

REPAIR STOP LIGHT SWITCH CIRCUIT

OK

2

CHECK TERMINAL VOLTAGE(STP OF SKID CONTROL ECU - BODY GROUND)

(a)

Disconnect the skid control ECU connector.

(b)

Measure the voltage between terminal STP of the skid
control ECU connector and the body ground when the
brake pedal is depressed.
OK:
Brake pedal is depressed: 10 - 14 V
Brake pedal is released: 0 V

OK

CHECK AND REPLACE BRAKE ACTUATOR
ASSY

NG

3

CHECK HARNESS AND CONNECTOR(STOP LAMP SWITCH - SKID CONTROL
ECU)(See page 

01-31

)

NG

CHECK AND REPLACE HARNESS AND
CONNECTOR

OK

CHECK AND REPLACE BRAKE ACTUATOR ASSY

F41939

Battery

24

W-B

2

+BM

GND

23

W-B

5

ABS No. 2

Engine Room R/B

S1

1G

1A

1

Engine Room J/B

EA

1

2

L

FL MAIN

B-G

Skid Control ECU with Actuator

1

Motor
Relay

GND

1

1

2

ALT

B-G

S1

S1

W-B

EB

W-B

W-B

05-270

-

DIAGNOSTICS

ABS WITH EBD SYSTEM

423

2002 LEXUS ES300 REPAIR MANUAL   (RM911U)

DTC

C1251/51 PUMP MOTOR IS LOCKED/OPEN CIRCUIT

IN PUMP MOTOR GROUND

CIRCUIT DESCRIPTION

DTC No.

DTC Detection Condition

Trouble Area

C1251/51

Conditions 1., 2. and 3. continue for 0.024 sec.:

1. While checking self diagnosis of ECU, after current

flows to motor for 0.3 sec. within 0.054 sec. from turning

OFF motor relay.

2. While checking self diagnosis of ECU, after current

flows to motor for 1.4 sec. within 0.054 sec. from turning

OFF motor relay

3. Motor relay contact turned OFF

ABS pump motor

WIRING DIAGRAM

055XT-02

-

DIAGNOSTICS

ABS WITH EBD SYSTEM

05-271

424

2002 LEXUS ES300 REPAIR MANUAL   (RM911U)

INSPECTION PROCEDURE

1

PERFORM ACTIVE TEST BY HAND-HELD TESTER(ABS PUMP MOTOR
OPERATION)

(a)

Select the item ”ABS MOT RELAY” in the ACTIVE TEST and operate the ABS motor relay on the hand-
held tester.

(b)

Check the operation sound of the ABS pump motor when operating it with the hand-held tester.
OK:
The operation sound of the ABS pump motor should be heard.

NG

CHECK AND REPLACE BRAKE ACTUATOR
ASSY

OK

PROCEED TO NEXT CIRCUIT INSPECTION SHOWN ON PROBLEM SYMPTOMS TABLE(See page

05-250

)

F41940

05-272

-

DIAGNOSTICS

ABS WITH EBD SYSTEM

425

2002 LEXUS ES300 REPAIR MANUAL   (RM911U)

DTC

AlwaysON MALFUNCTION IN ABS ECU

CIRCUIT DESCRIPTION

DTC No.

DTC Detection Condition

Trouble Area

Always ON

Detection of any conditions in 1. and 2.:

1. Skid control ECU internal malfunction is detected

2. There is a malfunction in the ECU internal circuit

Battery

Charging system

Skid control ECU

WIRING DIAGRAM

056AL-01