Subaru 2009 IMPREZA, Service Manual

Page: 2674 / 3619

PS-51
General Diagnostic Table
POWER ASSISTED SYSTEM (POWER STEERING)
10.General Diagnostic Table
A: INSPECTION
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1 If the tires or wheels are wider than standard, the load to power steering system is increased. Accordingly, in a condition, for
example before fluid warms-up, relief valve may work before reaching 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. If steering effort reduces normally, function is normal.
*
3 In cold weather or with insufficient warm up of the engine, steering effort may be heavy due to excessive drop of idling when
turning the steering wheel. In this case, start the vehicle with increasing engine speed than usual. If steering effort reduces nor-
mally, function is normal.
Trouble Possible cause Corrective action
• Steering effort is heavy in
all ranges.
• Steering effort is heavy at
stand still.
• Steering wheel vibrates
when turning. 1. Pulley belt
• Unequal length of pulley belts
• Contact with oil or grease
• Looseness or damage of the pulley belt
• Poor uniformity of the 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 tire out of specifications
*
1
• Improper wheel out of specifications
*
1
• Tires not properly inflated
Replace or reinflate.
3. Fluid
• Low fluid level
• Air entry in fluid
• Dust entry in fluid
• Fluid deterioration
• Inadequate warm 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 when turning the steering
wheel
*
3
Adjust or instruct cus-
tomer.
5. Measure the hydraulic pressure. <Ref. to PS-45, INSPECTION, Oil
Pump.> Replace the problem
parts.
6. Measure the steering wheel effort. <Ref. to PS-54, MEASUREMENT
OF STEERING EFFORT, INSPECTION, General Diagnostic Table.>
Adjust or replace.
• Vehicle leads to one side
or the other.
• Returning force of steering
wheel to center is poor.
• Steering wheel vibrates
when turning. 1. Fluid line
• Folded hose
• Flattened pipe
Repair or replace.
2. Tire and wheel
• Flat tire
• Mixed use of different tires
• Mixed use of different wheels
• Abnormal wear of tire
• Unequal tread remaining
• Unequal pressure of tire
Adjust, fix or replace.
3. Front alignment
• Improper or unequal caster
• Improper or unequal toe-in
• Loose suspension connections
Adjust or retighten.
4. Others
• Damaged joint assembly
• Unbalanced height
• Unbalanced weight
Replace, adjust or
instruct customer.
5. Measure the steering wheel effort. <Ref. to PS-54, MEASUREMENT
OF STEERING EFFORT, INSPECTION, General Diagnostic Table.>
Adjust or replace.