TOYOTA SIENNA 2007 Service Repair Manual

POWER STEERING – POWER STEERING SYSTEMPS–1
PS
POWER STEERING SYSTEM
PRECAUTION
1. HANDLING PRECAUTIONS ON STEERING SYSTEM
(a) Care must be taken when replacing parts. Incorrect
replacement could affect the performance of the
steering system and result in a driving hazard.
2. HANDLING PRECAUTIONS ON SRS AIRBAG
SYSTEM
(a) The vehicle is equipped with SRS (Supplemental
Restraint System) such as the driver airbag and
front passenger airbag. Failure to carry out service
operation in correct sequence could cause the SRS
to unexpectedly deploy during servicing, possibly
leading to a serious accident. Before servicing
(including removal or installation of parts, inspection
or replacement), be sure to read the precautionary
notice for the supplemental restraint system (See
page RS-1).

PS–2POWER STEERING – POWER STEERING SYSTEM
PS
PROBLEM SYMPTOMS TABLE
HINT:
Use the table below to help determine the cause of the
problem. Likely causes of the problem are indicated in
descending order. Check each suspected area in order.
Repair or replace the faulty parts or perform adjustments as
necessary.
POWER STEERING SYSTEM
ON-VEHICLE INSPECTION
1. INSPECT DRIVE BELT
(a) Visually check the drive belt for excessive wear,
frayed cords, etc.
If any defect is found, replace the drive belt.
HINT:
Cracks on the rib side of a belt are considered
acceptable. Replace the belt if there are any
missing ribs.
2. CHECK POWER STEERING FLUID LEVEL
(a) Keep the vehicle level.
Symptom Suspected Area See page
Hard steeringTires (Improperly inflated)TW-2
Power steering fluid level (Low)PS-2
Drive belt (Loose) -
Front wheel alignment (Incorrect)SP-4
Steering system joints (Worn) -
Suspension arm ball joints (Worn)SP-24
Steering column (Binding)SR-6
Power steering vane pumpPS-9
Power steering gearPS-24
Poor returnTires (Improperly inflated)TW-2
Front wheel alignment (Incorrect)SP-4
Steering column (Binding)SR-6
Power steering gearPS-24
Excessive playSteering system joints (Worn) -
Suspension arm ball joints (Worn)SP-24
Intermediate shaft, Sliding yoke (Worn) -
Front wheel bearing (Worn)AH-5
Power steering gearPS-24
Abnormal noisePower steering fluid level (Low)PS-2
Steering system joints (Worn) -
Power steering vane pumpPS-9
Power steering gearPS-24
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POWER STEERING – POWER STEERING SYSTEMPS–3
PS
(b) With the engine stopped, check the fluid level in the
fluid reservoir.
If necessary, add fluid.
Fluid:
ATF DEXRON II or III, or equivalent
HINT:
If the fluid is hot, check that the fluid level is within
the HOT range on the fluid reservoir. If the fluid is
cold, check that the fluid level is within the COLD
range.
(c) Start the engine and run it at idle.
(d) Turn the steering wheel from lock to lock several
times to raise fluid temperature.
Fluid temperature:
75 to 80
C (167 to 176F)
(e) Check for foaming or emulsification.
If foaming or emulsification is identified, bleed the
power steering system (See page PS-6).
(f) With the engine idling, measure the fluid level in the
fluid reservoir.
(g) Stop the engine.
(h) Wait a few minutes and remeasure the fluid level in
the fluid reservoir.
Maximum fluid level rise:
5 mm (0.20 in.)
If a problem is found, bleed the power steering
system (See page PS-6).
(i) Check the fluid level.
3. INSPECT STEERING FLUID PRESSURE
(a) Disconnect the pressure feed tube assembly from
the vane pump assembly (See page PS-9).
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PS–4POWER STEERING – POWER STEERING SYSTEM
PS
(b) Connect SST as shown in the illustration.
SST 09640-10010 (09641-01010, 09641-01060,
09641-01030)
NOTICE:
Check that the valve of SST is in the open
position.
(c) Bleed the power steering system (See page PS-6).
(d) Start the engine and run it at idle.
(e) Turn the steering wheel from lock to lock several
times to raise fluid temperature.
Fluid temperature:
75 to 80
C (167 to 176F)
(f) With the engine idling, close the valve of SST and
observe the reading on SST.
Standard fluid pressure:
7,800 to 8,300 kPa (79.5 to 84.6 kgf/cm
2, 1,131
to 1,204 psi)
NOTICE:
• Do not keep the valve closed for more than 10
seconds.
• Do not allow the fluid temperature to become
too high.
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POWER STEERING – POWER STEERING SYSTEMPS–5
PS
(g) With the engine idling, open the valve fully.
(h) Measure the fluid pressure at engine speeds of
1,000 rpm and 3,000 rpm.
Fluid pressure difference:
490 kPa (5 kgf/cm
2, 71 psi) or less
NOTICE:
Do not turn the steering wheel.
(i) With the engine idling and the valve fully opened,
turn the steering wheel left or right to the full lock
position. Observe the reading on SST.
Standard fluid pressure:
7,800 to 8,300 kPa (79.5 to 84.6 kgf/cm
2, 1,131
to 1,204 psi)
NOTICE:
• Do not keep the steering wheel in the full lock
position for more than 10 seconds.
• Do not allow the fluid temperature to become
too high.
(j) Disconnect SST.
(k) Connect the pressure feed tube assembly to the
vane pump assembly (See page PS-19).
(l) Bleed the power steering system (See page PS-6).
4. CHECK STEERING EFFORT
(a) Stop the vehicle on a level, paved surface and turn
the wheels straight ahead.
(b) Disconnect the negative (-) battery cable from the
battery.
CAUTION:
Wait at least 90 seconds after disconnecting the
cable from the negative (-) battery terminal to
prevent airbag and seat belt pretensioner
activation.
(c) Remove the steering pad (See page RS-423).
(d) Connect the negative (-) battery cable to the battery.
(e) Using a torque wrench, check if the steering wheel
set nut is properly tightened.
Torque: 50 N*m (510 kgf*cm, 37 ft.*lbf)
(f) Start the engine and run it at idle.
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PS–6POWER STEERING – POWER STEERING SYSTEM
PS
(g) Turn the steering wheel 90 degrees to the right and
check steering effort (torque) while turning the
wheel. Check the opposite direction in the same
manner.
Torque: Steering effort (Reference)
6.0 N*m (61 kgf*cm, 53 in.*lbf)
HINT:
Check the tire type, pressure, and the road surface
before making your diagnosis.
(h) Disconnect the negative (-) battery cable from the
battery.
(i) Tighten the steering wheel set nut.
Torque: 50 N*m (510 kgf*cm, 37 ft.*lbf)
(j) Install the steering pad (See page RS-424).
(k) Connect the negative (-) battery cable to the battery.
(l) Clear the DTCs (See page RS-35).
(m) Inspect the airbag warning light (See page RS-27).
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PS–6POWER STEERING – POWER STEERING FLUID
PS
POWER STEERING FLUID
BLEEDING
1. BLEED POWER STEERING SYSTEM
(a) Check the fluid level (See page PS-2).
(b) Jack up the front of the vehicle and support it with
stands.
(c) Turn the steering wheel.
(1) With the engine stopped, turn the steering
wheel slowly from lock to lock several times.
(d) Lower the vehicle.
(e) Start the engine.
(1) Run the engine at idle for a few minutes.
(f) Turn the steering wheel.
(1) With the engine idling, turn the steering wheel
left or right to the full lock position and keep it in
that position for 2 to 3 seconds, then turn the
steering wheel to the opposite full lock position
and keep it there for 2 to 3 seconds.
(2) Repeat this procedure several times.
(g) Stop the engine.
(h) Check for foaming or emulsification.
HINT:
If the system has to be bled twice because of
forming or emulsification, be sure to check for fluid
leaks in the system.
(i) Check the fluid level (See page PS-2).
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POWER STEERING – VANE PUMPPS–7
PS
STEERING
POWER STEERING
VANE PUMP
COMPONENTS
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PS–8POWER STEERING – VANE PUMP
PS
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POWER STEERING – VANE PUMPPS–9
PS
REMOVAL
1. DRAIN POWER STEERING FLUID
2. REMOVE FRONT WHEEL RH
3. REMOVE FRONT FENDER APRON SEAL RH (See
page EM-26)
4. REMOVE FAN AND GENERATOR V BELT (See page
EM-6)
5. DISCONNECT NO. 1 FLUID RESERVOIR TO PUMP
HOSE
(a) Slide the clip and disconnect the No. 1 fluid
reservoir to pump hose from the vane pump
assembly.
6. DISCONNECT PRESSURE FEED TUBE ASSEMBLY
(a) Remove the union bolt and disconnect the pressure
feed tube assembly from the vane pump assembly.
(b) Remove the gasket from the pressure feed tube
assembly.
7. DISCONNECT POWER STEERING FLUID PRESSURE
SWITCH CONNECTOR
(a) Disconnect the power steering fluid pressure switch
connector.
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