Lexus SC300 / Lexus SC400. Manual - part 744

POWER STEERING SYSTEM BLEEDING

SR0G2–04

1. 

CHECK FLUID LEVEL IN OIL RESERVOIR
Check the fluid level and add fluid if necessary.

Fluid:

ATF DEXRON



 II

HINT: Check that the fluid level is within the HOT LEVEL of
the dipstick of the reservoir cap. If the fluid is cold, check that
it is within the COLD LEVEL of the dipstick.

2.  START ENGINE AND TURN STEERING WHEEL FROM

LOCK TO LOCK 3 OR 4 TIMES
With the engine speed below 1,000 rpm, turn the steering
wheel to left or right full lock and keep it there for 2–3 se-
conds, then turn the wheel to the opposite full lock and keep
it there for 2–3 seconds.

3. 

CHECK THAT FLUID IN OIL RESERVOIR IS NOT FOAMY
OR CLOUDY AND DOES NOT RISE OVER MAXIMUM
WHEN ENGINE IS STOPPED
Measure the fluid level with the engine running. Stop the en-
gine and measure the fluid level.

Maximum rise:

5 mm (0.20 in.)

If a problem is found, repeat fluid replacement on page
SR–114. Rep air the PS if the problem persists.

OIL PRESSURE CHECK

SR0G3–03

1. 

CONNECT PRESSURE GAUGE

(a)  Using SST, disconnect the pressure line joint.

SC 400:
SST 09631–22020

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STEERING

POWER STEERING

SR–115

(b)  Connect the gauge side of the pressure gauge to the PS

pump side, and the valve side to the gear housing side.

2. 

BLEED POWER STEERING SYSTEM
(See page 

SR–115

)

3. 

START ENGINE AND RUN IT AT IDLE

4. 

BOOST FLUID TEMPERATURE
With the engine idling at 1,000 rpm or less, turn the steering
wheel from lock to lock several times to boost fluid tempera-
ture.

Fluid temperature: 80

C (176

F)

5. CHECK 

FLUID 

PRESSURE 

READING 

WITH 

VALVE

CLOSED
Close the pressure gauge valve and observe the reading on
the gauge.

Minimum pressure:

7,355 kPa (75 kgf/cm

2,

 1,067 psi)

NOTICE:

•

Do not keep the valve closed for more than 10 seconds.

•

Do not let the fluid temperature become too high.

If pressure is low, repair or replace the PS vane pump.

6. OPEN 

VALVE 

FULLY

7. 

CHECK AND RECORD PRESSURE READING AT 1,000
RPM

8.  CHECK AND RECORD PRESSURE READING AT 3,000

RPM
Check that the pressure difference between the 1,000 rpm
and 3,000 rpm checks is less than 490 kPa (5 kgf/cm

2

, 71

psi). If the difference is excessive, repair or replace the flow
control valve of the PS vane pump.

NOTICE: Do not operate the steering wheel.

SR–116

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STEERING

POWER STEERING

9. 

CHECK PRESSURE READING WITH STEERING WHEEL
TURNED TO FULL LOCK
Be sure the pressure gauge valve is fully opened and the en-
gine idling.

Minimum pressure:

7,355 kPa (75 kgf/cm

2,

 1,067 psi)

NOTICE:

•

Do not maintain lock position for more than 10 seconds.

•

Do not let the fluid temperature become too high.

If pressure is low, the gear housing has an internal leak and
must be repaired or replaced.

10.  MEASURE STEERING EFFORT
(a)  Center the steering wheel and run the engine at idle.
(b)  Using a spring scale, measure the steering effort in both

directions.

Maximum steering effort:

40 N (4.1 kgf, 9.0 lbf)

If steering effort is excessive, repair the power steering unit.
HINT: Be sure to consider the tire type, pressure and contact
surface before making your diagnosis.

(c)  Disconnect the solenoid connector.

(d)  Using a spring scale, measure the steering effort in both

directions.
(Reference)

Maximum steering effort:

76 N (7.7 kgf, 17.0 lbf)

If steering effort is not heavier than (b), check solenoid.
HINT: Be sure to consider the tire type, pressure and contact
surface before making your diagnosis.

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STEERING

POWER STEERING

SR–117

POWER STEERING PUMP
(SC400)
POWER STEERING PUMP REMOVAL
AND INSTALLATION

SR0G4–01

Remove and install the parts, as shown.

MAIN POINTS OF REMOVAL AND
INSTALLATION

1. 

REMOVE DRIVE BELT
Loosen the drive belt tension by turning the drive belt tension-
er counterclockwise, and remove the drive belt.

SR–118

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STEERING

POWER STEERING