Lexus SC300 / Lexus SC400. Service manual — part 275

OK

NG

OK

NG

INSPECTION PROCEDURES

1

Check operation of TRAC pump & motor.

C

OK

P

Notice

Disconnect TRAC pump & motor connector.

Connect positive

lead to terminal 3 or TRAC pump &

motor connector and negative

lead to terminal 1.

Do not apply battery voltage for more than 3 sec.

The TRAC pump motor should emit an operating
sound.

Go to step 3.

2

Check continuity between terminal 1 of TRAC pump & motor connector and body ground.

C

OK

Measure resistance between terminal 1 of TRAC pump
& motor connector and body ground.

Resistance:

0

(Continuity)

Repair or replace harness or connector.

Replace TRAC pump & motor.

BR–128

–

BRAKE SYSTEM

ANTI–LOCK BRAKE SYSTEM (ABS)

OK

NG

NG

OK

OK

NG

3

Check harness and connector between ABS & TRAC ECU and TRAC pump & motor (See page

IN–33

).

Repair or replace harness or connector.

4

Check voltage between terminals PR and E2 of ABS & TRAC ECU connector.

C

OK

P

OK

C

Notice

1.

Remove ABS & TRAC ECU with connectors still
connected.

2.

Operate the engine for about 30 seconds at idle
speed to raise the pressure of the TRAC actuator
to a high level.

1.

Stop the engine and then turn ignition switch ON.

2.

Measure voltage between terminals PR and E2 of
ABS & TRAC ECU connector.

Voltage:

4 – 8 V

1.

Drain the fluid out of the actuator to reduce the pres-
sure.

2.

Measure voltage between terminal PR and E2 of
ABS & TRAC ECU connector.

Voltage:

10 – 14 V

Add fluid to reservoir after the check.

Check and replace ABS & TRAC ECU.

5

Check harness and connector between ABS & TRAC ECU and TRAC actuator (See page

IN–33

).

Repair or replace harness or connector.

Replace TRAC actuator.

–

BRAKE SYSTEM

ANTI–LOCK BRAKE SYSTEM (ABS)

BR–129

BR–22

8

WIRING DIAGRAM

DTC

54

Excessive Operation of TRAC Pump Motor

CIRCUIT DESCRIPTION

DTC No.

DTC Detecting Condition

Trouble Area

54

TRAC motor relay ON is output continuously10 times

at intervals of less than 24 sec.when traction control is

not being executed.

TRAC Actuator

TRAC Accumulator

Brake fluid leakage

ECU

DIAGNOSTIC CHART

DIAGNOSTIC CHART

BR–130

–

BRAKE SYSTEM

ANTI–LOCK BRAKE SYSTEM (ABS)

NG

OK

OK

NG

INSPECTION PROCEDURES

1

Check voltage between terminals PR and E21 of ABS & TRAC ECU connector.

C

OK

P

1.

Remove ABS & TRAC ECU with connectors still
connected.

2.

Operate the engine for about 30 seconds at idle
speed to raise the pressure of the TRAC actuator
to a high level.

1.

Stop the engine and then turn ignition switch ON.

2.

Measure voltage between terminals PR and E2 of
ABS & TRAC ECU connector.

Voltage:

4 – 8 V for more than 24 sec.

Check and replace ABS & TRAC ECU.

2

Check for brake fluid leakage.

See page

BR–150

.

Repair brake fluid leakage and add fluid.

Replace TRAC accumulator.
If TRAC accumulator is replaced and the problem is still occurring, replace TRAC actuator.

–

BRAKE SYSTEM

ANTI–LOCK BRAKE SYSTEM (ABS)

BR–131