2000 LEXUS GS400 Service Repair Manual

D01827
± BRAKEHYDRAULIC BRAKE BOOSTER
BR±39
2147 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
2. IN CASE OF USING LEXUS HAND±HELD TESTER:
INSPECT HYDRAULIC BRAKE BOOSTER OPERA-
TION
(a) Inspect the battery positive voltage.
Battery positive voltage: 10 ± 14 V
(b) Turn the ignition switch OFF, depress the brake pedal
more than 40 times.
(c) Check that the brake pedal becomes heavy to depress.
If the pedal does not become to be heavy to depress, check and
replace the brake line and hydraulic brake booster.
(d) Turn the ignition switch ON, check the pump motor opera-
tion noise.
If the pump motor does not operate, check and replace the wire
harness and pump motor (See page BR±53).
(e) Connect the LEXUS hand±held tester.
(1) Connect the LEXUS hand±held tester to the DLC3.
(2) Turn the ignition switch ON.
(3) Select the ºACTIVE TESTº mode on the LEXUS
hand±held tester.
HINT:

Please refer to the LEXUS hand±held tester operator's
manual for further details.

To protect the solenoids, hand±held tester turns OFF au-
tomatically 2 secs. after every solenoid has been turned
ON.
(f) Inspect the front TRAC & VSC solenoid operation.
(1) Select ºSA1º and ºSA2º on the LEXUS hand±held
tester.
(2) With ºSA1º and ºSA2º turned ON simultaneously
with the LEXUS hand±held tester, depress the
brake pedal with stable force and check that the
pedal cannot be depressed.
HINT:
To protect the solenoids, LEXUS hand±held tester turns OFF
automatically 2 sec. after every solenoid has been turned ON.
If the pedal can be depressed, replace the hydraulic brake
booster.
NOTICE:
When operating it continuously, set the interval of more
than 20 seconds.
(3) Once, release the brake pedal.

BR±40
± BRAKEHYDRAULIC BRAKE BOOSTER
2148 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
(4) When the solenoids are OFF, after depressing the
brake pedal again and check that the brake pedal
can be depressed.
If the pedal cannot be depressed, replace the hydraulic brake
booster.
(g) Inspect the front ABS solenoid operation.
(1) Select ºSFRHº and ºSFLHº on the LEXUS hand±
held tester.
(2) With ºSFRHº and ºSFLHº turned ON simultaneously
with the LEXUS hand±held tester, depress the
brake pedal with stable force and check that the
brake pedal cannot be depressed.
HINT:
To protect the solenoids, hand±held tester turns OFF automati-
cally 2 sec. after every solenoid has been turned ON.
If the pedal can be depressed, replace the hydraulic brake
booster.
(3) Once, release the brake pedal when the solenoids
are OFF, check that the brake pedal can be de-
pressed.
If the pedal cannot be depressed, replace the hydraulic brake
booster.
(4) Once, release the brake pedal. After depressing
and holding the brake pedal with stable force, turn
the SFRH and SFRR solenoids ON simultaneously.
HINT:
To protect the solenoids, hand±held tester turns OFF automati-
cally 2 sec. after every solenoid has been turned ON.
(5) When the solenoids are OFF, check that the brake
pedal can be depressed.
If the pedal cannot be depressed, replace the hydraulic brake
booster.
(6) Once, release the brake pedal. After depressing
and holding the brake pedal with stable force, turn
the SFLH and SFLR solenoids ON simultaneously.
HINT:
To protect the solenoids, hand±held tester turns OFF automati-
cally 2 sec. after every solenoid has been turned ON.
(7) When the solenoids are OFF, check that the brake
pedal can be depressed.
If the pedal cannot be depressed, replace the hydraulic brake
booster.
(h) Jack up and support the vehicle.
(i) Release the parking brake pedal.
(j) Shift the shift lever to ºNº position and check that the rear
wheels by rotating them by hand.
(k) Inspect the rear TRAC & VSC solenoid operation.
(1) Select the ºSA3º and ºSTRº on the LEXUS hand±
held tester.

± BRAKEHYDRAULIC BRAKE BOOSTER
BR±41
2149 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
(2) Turn the ºSA3º and ºSTRº ON simultaneously with
the LEXUS hand±held tester, and check that the
rear wheels by does not rotate by hand.
HINT:
When rotating the wheel fast, the fail±safe function is activated
and judgement cannot be made properly. So rotate the wheel
as slowly as possible.
If the rear wheels rotate, replace the hydraulic brake booster.
(3) Turn the ºSA3º and ºSTRº OFF simultaneously, and
check that the rear wheels by rotating them by
hand.
HINT:

To protect the solenoids, LEXUS hand±held tester turns
OFF automatically 2 sec. after every solenoid has been
turned ON.

When rotating the wheel fast, the fail±safe function is acti-
vated and judgement cannot be made properly. So rotate
the wheel as slowly as possible.
NOTICE:
When operating it continuously, set the interval of more
than 20 secs.
If the rear wheels stop, replace the hydraulic brake booster.
(l) Inspect the right rear ABS solenoid.
(1) Select the ºSA3º, ºSTRº and ºSRRHº, on the LEXUS
hand±held tester.
(2) Turn the ºSA3º, ºSTRº and ºSRRHº ON simulta-
neously with the LEXUS hand±held tester, and
check that the right rear wheel by rotating it by hand.
HINT:

To protect the solenoids, LEXUS hand±held tester turns
OFF automatically 2 sec. after every solenoid has been
turned ON.

When rotating the wheel fast, the fail±safe function is acti-
vated and judgement cannot be made properly. So rotate
the wheel as slowly as possible.

When solenoid is OFF, the wheel might stop temporarily.
However if the wheel rotates again, the function works
normally.
If the rear wheels stop, replace the hydraulic brake booster.
(3) Turn the ºSA3º, ºSTRº and ºSRRHº OFF, and check
that the right rear wheel by rotating it by hand.
HINT:

To protect the solenoids, LEXUS hand±held tester turns
OFF automatically 2 sec. after every solenoid has been
turned ON.

When rotating the wheel fast, the fail±safe function is acti-
vated and judgement cannot be made properly. So rotate
the wheel as slowly as possible.
If the right rear wheel stop, replace the hydraulic brake booster.

BR±42
± BRAKEHYDRAULIC BRAKE BOOSTER
2150 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
(4) Depress the pedal with stable force, then turn the
ºSRRHº and ºSRRRº ON simultaneously.
(5) When the solenoids are ON, check that the right
rear wheel by rotating it by hand.
(m) Inspect the left rear ABS solenoid operation.
(1) Select the ºSA3º, ºSTRº and ºSRLHº on the LEXUS
hand±held tester.
(2) Turn the ºSA3º, ºSTRº and ºSRLHº ON with LEXUS
hand±held tester, and check that the left rear wheel
by rotating it by hand.
HINT:
When rotating the wheel fast, the fail±safe function is activated
and judgement cannot be made properly. So rotate the wheel
as slowly as possible.
If the rear wheels stop, replace the hydraulic brake booster.
(3) Turn the ºSA3º, ºSTRº and ºSRLHº OFF and check
that the left rear wheel by rotating it by hand.
HINT:

To protect the solenoids, LEXUS hand±held tester turns
OFF automatically 2 sec. after every solenoid has been
turned ON.

When rotating the wheel fast, the fail±safe function is acti-
vated and judgement cannot be made properly. So rotate
the wheel as slowly as possible.

When solenoid is OFF, the wheel might stop temporarily.
However if the wheel rotates again, the function works
normally.
If the left rear wheel stop, replace the hydraulic brake booster.
(4) Depress the pedal with stable force, then turn the
ºSRLHº and ºSRLRº ON simultaneously.
HINT:
To protect the solenoids, LEXUS hand±held tester turns OFF
automatically 2 sec. after every solenoid has been turned ON.
(5) When the solenoids are ON, check that the left rear
wheel by rotating it by hand.
HINT:
When rotating the wheel fast, the fail±safe function is activated
and judgement cannot be made properly. So rotate the wheel
as slowly as possible.
(n) Lower the vehicle.
(o) Disconnect the LEXUS hand±held tester.

F06049
F02821
Hydraulic Brake
BoosterSub±Wire harness S (SST)
FRONT
REAR
AIR BLEEDActuator Checker (SST)
± BRAKEHYDRAULIC BRAKE BOOSTER
BR±43
2151 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
3. IN CASE OF USING ABS ACTUATOR CHECKER:
INSPECT HYDRAULIC BRAKE BOOSTER OPERA-
TION
(a) Inspect the battery positive voltage.
Battery positive voltage: 10 ± 14 V
(b) Disconnect the 2 connectors from hydraulic brake boost-
er.
(c) Connect the actuator checker (SST) to the hydraulic
brake booster side wire harness via the sub±wire harness
S (SST), as shown in the chart below.
SST 09990±00150, 09990±00480
HINT:
Connect the connector with the label of ºFRONTº attached to
the connector of actuator checker.
(d) Connect the red cable of the checker to the battery posi-
tive (+) terminal and the black cable to the negative (±) ter-
minal.
(e) Place ºSHEET Gº (SST) of ºFRONTº on actuator checker.
SST 09990±00240
(f) Turn the ignition switch OFF, depress the brake pedal
more than 40 times.
(g) Check that the brake pedal becomes heavy to depress.
If the pedal does not become to be heavy to depress, check and
replace the brake line and hydraulic brake booster.
(h) Turn the ignition switch ON, check the pump motor opera-
tion noise.
If the pump motor does not operate, check and replace the wire
harness and pump motor.

F04706
F02828
F02827
BR±44
± BRAKEHYDRAULIC BRAKE BOOSTER
2152 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
(i) Inspect the front TRAC & VSC solenoid operation.
(1) Push in and hold the ºSA1º and ºSA2º switches si-
multaneously, depress strongly and hold the brake
pedal with stable force.
NOTICE:
Do not keep the ºSA1º and ºSA2º pushed down for more
than 10 seconds. When operating it continuously, set the
interval of more than 20 seconds.
(2) Check that the brake pedal cannot be depressed.
If the pedal can be depressed, replace the hydraulic brake
booster.
(3) Release the ºSA1º switch and check that the brake
pedal can be depressed.
If the pedal cannot be depressed, replace the hydraulic brake
booster.
(4) Release the ºSA2º switch and check that the brake
pedal can be depressed.
If the pedal cannot be depressed, replace the hydraulic brake
booster.
(j) Inspect the right front ABS solenoid operation.
(1) Turn the selector switch to ºRHº position.
(2) Push and hold in the MAIN push switch and ºSA2º
switch simultaneously, depress and hold the brake
pedal with stable force.
NOTICE:
Do not keep the MAIN push switch and ºSA2º switch
pushed down for more than 10 seconds. When operating
it continuously, set the interval of more than 20 seconds.
(3) Check that the brake pedal cannot be depressed.
If the pedal can be depressed, replace the hydraulic brake
booster.
(4) Release the MAIN push switch and ºSA2º switch si-
multaneously and check that the brake pedal can
be depressed.
If the pedal cannot be depressed, replace the hydraulic brake
booster.
(5) Release the brake pedal.
(6) Depress and hold the brake pedal with stable force,
push and hold in MAIN push switch.
NOTICE:
Do not keep the MAIN push switch pushed down for more
than 10 seconds. When operating it continuously, set the
interval of more than 20 seconds.
(7) Check that the brake pedal cannot be depressed.
If the pedal can be depressed, replace the hydraulic brake
booster.

F04707
F02829
± BRAKEHYDRAULIC BRAKE BOOSTER
BR±45
2153 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
(8) Release the MAIN push switch, and check that the
brake pedal can be depressed.
If the pedal cannot be depressed, replace the hydraulic brake
booster.
(9) Release the brake pedal.
(k) Inspect the left front ABS solenoid operation.
(1) Turn the selector switch to ºLHº position.
(2) Push and hold in the MAIN push switch and ºSA1º
switch simultaneously, depress and hold the brake
pedal with stable force.
NOTICE:
Do not keep the MAIN push switch and ºSA1º switch
pushed down for more than 10 seconds. When operating
it continuously, set the interval of more than 20 seconds.
(3) Check that the brake pedal cannot be depressed.
If the pedal can be depressed, replace the hydraulic brake
booster.
(4) Release the MAIN push switch and ºSA1º switch si-
multaneously, and check that the brake pedal can
be depressed.
If the pedal cannot be depressed, replace the hydraulic brake
booster.
(5) Release the brake pedal.
(6) Depress and hold the brake pedal with stable force,
push and hold in MAIN push switch.
NOTICE:
Do not keep the MAIN push switch pushed down for more
than 10 seconds. When operating it continuously, set the
interval of more than 20 seconds.
(7) Check that the brake pedal cannot be depressed.
If the pedal can be depressed, replace the hydraulic brake
booster.
(8) Release the MAIN push switch, and check that the
brake pedal can be depressed.
If the pedal cannot be depressed, replace the hydraulic brake
booster.
(9) Release the brake pedal.
(l) Turn the ignition switch OFF, then reconnect the connec-
tor of sub±wire harness from the one with label of
ºFRONTº to ºREARº.
(m) Place ºSHEET Gº of ºREARº on the actuator checker.
(n) Jack up and support the vehicle.
(o) Start the engine and run it at idle.

F02830
F02831
BR±46
± BRAKEHYDRAULIC BRAKE BOOSTER
2154 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
(p) Inspect the rear TRAC & VSC solenoid.
(1) Release the parking brake pedal and shift the shift
lever to ºLº position.
(2) Push and hold the ºSA3º switch and ºSTRº switch
simultaneously.
NOTICE:

Do not keep the ºSTRº switch pushed down for more
than 10 seconds.

Do not keep the ºSA3º switch pushed down for more
than 5 seconds.

When operating it continuously, set the interval of
more than 20 seconds.
(3) Check that the rear wheels stop.
If the rear wheels rotate, replace the hydraulic brake booster.
(4) Release the ºSA3º switch and ºSTRº switch simulta-
neously.
(5) Check that the rear wheels rotate.
If the rear wheels stop, replace the hydraulic brake booster.
(q) Inspect the right rear ABS solenoid.
(1) Turn the selector switch to ºRHº position.
(2) Depress the brake pedal several times and release
the brake pedal when the pump begins rotating.
Wait until the pump stops.
(3) Turn the ignition switch OFF.
(4) Depress the brake pedal with a force of 343 N (35
kgf, 77 lbf), record the fluid surface in the reservoir
tank of the hydraulic brake booster.
(5) Press the MAIN push switch for 10 sec., and check
that the fluid surface in the reservoir tank of the hy-
draulic brake booster does not rise up at this time.
If the fluid surface level rises up, replace the hydraulic brake
booster.
NOTICE:
Do not press MAIN push switch for more than 10 sec. When
operating the switch continuously, do it an interval of more
than 20 seconds.
(6) Start the engine and run it at idle.
(7) Depress the brake pedal.
(8) Release the parking brake pedal and shift the shift
lever to ºLº position.
(9) Once, release the brake pedal. After depressing the
brake pedal with stable force, then push and hold
MAIN push switch.
(10) Check that the right rear wheel rotates.
If the right rear wheel stops, replace the hydraulic brake boost-
er.