Subaru Impreza 2003, Service Manual

Page: 2713 / 3610

PS-89
POWER ASSISTED SYSTEM (POWER STEERING)
GENERAL DIAGNOSTIC TABLE
12.General Diagnostic Table
A: INSPECTION
*1 If tires and/or wheels are wider, the load to power steering system is the more. 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 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
steering wheel from stop to stop several times to warm-up fluid. Then if steering effort reduces normally, there is no abnormal
thing.
*3 In cold weather or with insufficient warm-up of engine, steering effort may be heavy due to excessive drop of idling when turn-
ing steering wheel. In this case, it is recommended to start the vehicle with increasing engine speed than usual. 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
• Improper wheels out of specification
• Tires not properly inflated *1
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 the customer.
4. Idle speed
• Lower idle speed
• Excessive drop of idle speed at start or at turning steering
wheel *3
Adjust or instruct the customer.
5. Measure hydraulic pressure.<Ref. to PS-83, INSPECTION,
Oil Pump.>
Replace the problem parts.
6. Measure steering effort.<Ref. to PS-89, INSPECTION, Gen-
eral 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
Reform 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
• One-sided weight
Replace, adjust or instruct the
customer.
5. Measure steering effort.<Ref. to PS-89, INSPECTION, Gen-
eral Diagnostic Table.>
Adjust or replace.