Subaru 2004 LEGACY, Service Manual

Page: 604 / 609

PS-85
POWER ASSISTED SYSTEM (POWER STEERING)
General Diagnostic Table
12.General Diagnostic Table
A: INSPECTION
*1 If the tires or wheels are wider than specifications, the load to power steering system is increased. Accordingly, in a condition,
for example before fluid warms-up, relief valve may work before maximum turning angle. In this case, steering effort may be
heavy. When the measured hydraulic pressure is normal, there is no abnormal thing.
*2 In cold weather, steering effort may be heavy due to increased flow resistance of cold fluid. After warming-up engine, turn the
steering wheel from stop to stop several times to warm-up fluid. Then if steering effort reduces normally, there is no abnormal
thing.
Trouble Possible cause Corrective action
• Heavy steering effort in all
ranges
• Heavy steering effort at
stand still
• Steering wheel surges when
turning. 1. Pulley belt
• Unequal length of pulley belts
• Adhesion of oil and grease
• Loose or damage of pulley belt
• Poor uniformity of pulley belt cross section
• Pulley belt touches to pulley bottom
• Poor revolution of pulleys except oil pump pulley
• Poor revolution of oil pump pulley
Adjust or replace.
2. Tire and wheel
• Improper tires out of specification*1
• Improper wheel out of specification*1
• Tires not properly inflated
Replace or reinflate.
3. Fluid
• Low fluid level
• Aeration
• Dust mix
• Deterioration of fluid
• Poor warming-up of fluid *2
Refill, bleed air, replace or
instruct customer.
4. Idle speed
• Lower idle speed
• Excessive drop of idle speed at start or at turning steering
wheel *3
Adjust or instruct customer.
5. Measure hydraulic pressure. <Ref. to PS-80, INSPECTION,
Oil Pump.>
Replace the problem parts.
6. Measure steering effort. <Ref. to PS-88, MEASUREMENT
OF STEERING EFFORT, INSPECTION, General Diagnostic
Table.>
Adjust or replace.
• Vehicle leads to one side or
the other
• Poor return of steering wheel
to center
• Steering wheel surges when
turning. 1. Fluid line
• Folded hose
• Flattened pipe
Correct or replace.
2. Tire and wheel
• Flat tire
• Mix use of different tires
• Mix use of different wheels
• Abnormal wear of tire
• Unbalance of remained grooves
• Unbalance of tire pressure
Adjust, fix or replace.
3. Front alignment
• Improper or unbalance caster
• Improper or unbalance toe-in
• Loose connection of suspension
Adjust or retighten.
4. Others
• Damaged joint assembly
• Unbalanced height
• Unbalanced weight
Replace, adjust or instruct cus-
tomer.
5. Measure steering effort. <Ref. to PS-88, MEASUREMENT
OF STEERING EFFORT, INSPECTION, General Diagnostic
Table.>
Adjust or replace.