Lexus ES300 (2002 year). Manual - part 310

F41990

Skid Control ECU

Driver Side J/B

3

S7

STP

Passenger Side j/B

S13
Stop Light SW

2G

7

4

2M

ST+

51

61

2

3A

3A

A

G-W

G-W

SB

R14
Rear Combination
Light RH

R12
Rear Combination
Light LH

STOP

BC

BE

J12 
J/C

STOP

3

1

3

1

G-W

G-W

G-W

G-W

W-B

W-B

STOP

2G

13

15

2K

2E

1

W

From Battery

L4 
Light Failure Sensor

G-W

7

2

ST-

1

-

DIAGNOSTICS

ABS WITH EBD & BA & TRAC & VSC SYSTEM

05-359

512

2002 LEXUS ES300 REPAIR MANUAL   (RM911U)

DTC

C1249/49 OPEN CIRCUIT IN STOP LIGHT SWITCH

CIRCUIT

CIRCUIT DESCRIPTION

DTC No.

DTC Detecting Condition

Trouble Area

C1249/49

ECU terminal IG1 voltage is 9.5 to 18.5 V and ABS is in

non-operation, the open in circuit stop light switch circuit

continues for 10 sec. or more.

Stop light bulb

Stop light switch circuit

WIRING DIAGRAM

0529S-03

F40456

STP

05-360

-

DIAGNOSTICS

ABS WITH EBD & BA & TRAC & VSC SYSTEM

513

2002 LEXUS ES300 REPAIR MANUAL   (RM911U)

INSPECTION PROCEDURE

1

CHECK STOP LAMP SWITCH OPERATION

CHECK:
Check that the stop light lights up when brake pedal is depressed and turns off when the brake pedal is re-
leased.

OK

Go to step 3

NG

2

CHECK STOP LAMP SWITCH CIRCUIT

NG

REPAIR OR REPLACE STOP LAMP SWITCH
CIRCUIT

OK

3

CHECK SKID CONTROL ECU TERMINAL VOLTAGE(STP TERMINAL)

(a)

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

(b)

Measure voltage between terminal STP of skid control
ECU and body ground when brake pedal is depressed.
OK: 8 - 14 V

(c)

Measure voltage between terminal STP of skid control
ECU and body ground when brake pedal is released.
OK: Below 1.5 V

OK

CHECK AND REPLACE SKID CONTROL ECU
ASSY

NG

4

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

01-31

)

NG

REPAIR OR REPLACE HARNESS OR
CONNECTOR

OK

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

05-308

)

F41979

Battery

FL MAIN

Skid Control ECU

ALT

EB

ABS R/B

W-R

24

MRF

Engine Room R/B

S8

S5

1

23

14

R+

MR

MT

ABS & Traction Actuator

ABS MTR Relay

A5

A5

A5

A5

1

4

3

2

2

2

2

2

2

1

3

5

1G

1A

1

1

1

2

5

ABS
No. 2

Engine Room J/B

GR-L

W-L

GR-L

GR-R

+BM

MR

MT

GND

W-B

W-B

R-W

B-G

1

2

1

S8

S8

B-G

-

DIAGNOSTICS

ABS WITH EBD & BA & TRAC & VSC SYSTEM

05-361

514

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

055W8-02

05-362

-

DIAGNOSTICS

ABS WITH EBD & BA & TRAC & VSC SYSTEM

515

2002 LEXUS ES300 REPAIR MANUAL   (RM911U)

INSPECTION PROCEDURE

Start the inspection from step 1 in case of using the hand-held tester and start from step 2 in case of not
using hand-held tester.

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 pump motor should be heard.

NG

REPLACE ABS & TRACTION ACTUATOR ASSY

OK

2

RECONFIRM DTC(See page 

05-288

)

A

Normal Code

B

Malfunction Code

B

CHECK AND REPLACE SKID CONTROL ECU
ASSY

A

END