Lexus ES300 (1997 year). Service manual - part 378

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DIAGNOSTICS

ABS & TRACTION CONTROL SYSTEM

DI–289

441

1997 LEXUS ES300   (RM511U)

DTC

21 to 28

ABS & TRAC Actuator Solenoid Circuit

CIRCUIT DESCRIPTION

This solenoid goes on when signals are received from the ECU and controls the pressure acting on the wheel
cylinders thus controlling the braking force.

DTC No.

DTC Detecting Condition

Trouble Area

21

ABS actuator

SFRR or SFRH circuit

ECU

22

ABS actuator

SFLR or SFLH circuit

ECU

23

Conditions (1) and (2) or (3) continued for 0.48 sec. or

more:

ABS actuator

SRRR or SRRH circuit

ECU

24

(1) Recovery prohibit run pulse is not output, solenoid 

     relay is ON, AST voltage of ECU terminal is 8.0 V or

     more, and solenoid output has no change between the

last time and this time

ABS actuator

SRLR or SRLH circuit

ECU

25

   last time and this time.

(2) Solenoid output is ON, pressure holding solenoid 

     monitor voltage is more than 1.0 V or pressure 

reduction solenoid monitor voltage is more than 1 5 V

ABS actuator

SMC1 circuit

ECU

26

       reduction solenoid monitor voltage is more than 1.5 V.

(3) Solenoid output is OFF, solenoid monitor voltage is

    more than –1.0 V AST voltage of ECU.

ABS actuator

SMC2 circuit

ECU

27

ABS actuator

SRC1 circuit

ECU

28

ABS actuator

SRC2 circuit

ECU

Fail safe function: If trouble occurs in the actuator solenoid circuit, the ECU cuts off current to the ABS 
                             & TRAC solenoid relay and prohibits ABS control and TRAC control.

DI0C4–01

F00084

Engine Room R/B No. 3

6

4

DLC1

ABS & TRAC Actuator

A19

A7

A8

12

A21

GR

5

SFLH

GR–R

SRLH

ABS & TRAC ECU

3

ABS & TRAC 

Solenoid Relay

2

1

ALT

F6

F9

ABS

FL 

Block

W–L

SMC2

MAIN

W–B

B–G

Battery

SRRH

SFRR

SRLR

AST

EA

4

EB

1

B–G

3

3

3

3

3

W–B

W–B

1

2 1

3

A7

A8

A8

A8

A8

A8

A8

A8

A8

A8

A8

A8

A19

A19

A19

A19

A19

A19

A21

A21

A21

A21

A21

A21

A21

7

8

9

10

11

13

25

26

R

SFRH

1

2

5

6

4

3

5

1

11

2

8

12

1

7

5

4

12

6

10

R–B

G–Y

R–G

LG–B

SR

R+

W–R

L–B

B–Y

B–R

Y–B

Y–R

W–R

W–L

SFLR

SRRR

SRC1

SMC1

SRC2

Engine Room R/B No. 3

6

4

DLC1

ABS & TRAC Actuator

A19

A7

A8

12

A21

GR

5

SFLH

GR–R

SRLH

ABS & TRAC ECU

3

ABS & TRAC 

Solenoid Relay

2

1

ALT

F6

F9

ABS

FL 

Block

W–L

SMC2

MAIN

W–B

B–G

Battery

SRRH

SFRR

SRLR

AST

EA

4

EB

1

B–G

3

3

3

3

3

W–B

W–B

1

2 1

3

A7

A8

A8

A8

A8

A8

A8

A8

A8

A8

A8

A8

A19

A19

A19

A19

A19

A19

A21

A21

A21

A21

A21

A21

A21

7

8

9

10

11

13

25

26

R

SFRH

1

2

5

6

4

3

5

1

11

2

8

12

1

7

5

4

12

6

10

R–B

G–Y

R–G

LG–B

SR

R+

W–R

L–B

B–Y

B–R

Y–B

Y–R

W–R

W–L

SFLR

SRRR

SRC1

SMC1

SRC2

F00057

1

2

3

4

5

6

7

8

9

10

11

12

A7

A8

4

1

2

3

4

5

6

7

8

9

10

11

12

A7

A8

4

1

2

3

4

5

6

7

8

9

10

11

12

A7

A8

4

1

2

3

4

5

6

7

8

9

10

11

12

A7

A8

4

1

2

3

4

5

6

7

8

9

10

11

12

A7

A8

4

1

2

3

4

5

6

7

8

9

10

11

12

A7

A8

4

DI–290

–

DIAGNOSTICS

ABS & TRACTION CONTROL SYSTEM

442

1997 LEXUS ES300   (RM511U)

WIRING DIAGRAM

INSPECTION PROCEDURE

1

Check ABS & TRAC actuator solenoid.

PREPARATION:
Disconnect the 2 connectors from ABS & TRAC actuator.
CHECK:
Check continuity between terminals A7 – 4 and A8 – 1, 2, 3, 4,
5, 6, 7, 8, 9, 10, 11, 12 of ABS & TRAC actuator connector.
OK:

Continuity

HINT:Resistance of each solenoid coil is 1.2

 Ω

.

NG

Replace ABS & TRAC actuator.

OK

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DIAGNOSTICS

ABS & TRACTION CONTROL SYSTEM

DI–291

443

1997 LEXUS ES300   (RM511U)

2

Check for open and short in harness and connector between ABS & TRAC ECU
and actuator (See page 

IN–27

).

NG

Repair or replace harness or connector.

OK

If the same code is still output after the DTC is deleted, check the contact condition of each con-
nection. 
If the connections are normal, the ECU may be defective.

BR3583
BR3582

F00010

Rotor

Speed Sensor

Magnet

To ECU

+V

–V

High Speed

Low Speed

Coil

N

S

DI–292

–

DIAGNOSTICS

ABS & TRACTION CONTROL SYSTEM

444

1997 LEXUS ES300   (RM511U)

DTC

31, 32, 33, 34

Speed Sensor Circuit

CIRCUIT DESCRIPTION

The speed sensor detects wheel speed and sends the ap-
propriate signals to the ECU. These signals are used to control
of the ABS and TRAC system. The front and rear rotors each
have 48 serrations.
When the rotors rotate, the magnetic field emitted by the perma-
nent magnet in the speed sensor generates an AC voltage.
Since the frequency of this AC voltage changes in direct propor-
tion to the speed of the rotor, the frequency is used by the ECU
to detect the speed of each wheel.

 

DTC No.

DTC Detecting Condition

Trouble Area

31, 32, 33, 34

Detection of any of conditions from (1) through (3):

(1) ABS non–operation, wheel speed is 10 km/h or 

     more, one eighth of maximum wheel speed is greater

    than the minimum wheel speed, one eighth of 

     maximum wheel speed is smaller than the rear 

    maximum wheel speed or momentary interruption of

    both the rear wheels are shown in the 15 sec. or more

   continuously.

(2) ABS non–operation, momentary interruption of speed

    sensor occurs 7 times or more in the mean time of

   switching the ignition switch ON and OFF or vehicle

    speed is 20 km/h (12 mph) or more and the condition 

       of noise interference or non–noise interference occurs

    75 times or more within 5 sec.

(3) Vehicle is at a stop, malfunction signal of vehicle speed

   sensor hardware open circuit is ON for 1.02 sec. 

    continuously since starting the checking of a certain 

    vehicle.

Right front, left front, right rear, left rear speed sensor

Each speed sensor circuit

Speed sensor rotor

ECU

HINT:
DTC No. 31 is for the right front speed sensor.
DTC No. 32 is for the left front speed sensor.
DTC No. 33 is for the right rear speed sensor.
DTC No. 34 is for the left rear speed sensor.
Fail safe function: If trouble occurs in the speed sensor circuit, the ECU cuts off current to the ABS & TRAC
                             solenoid relay and prohibits ABS control and TRAC control.

DI0C5–01