power steering ISUZU AXIOM 2002 Service User Guide

2A±2
POWER±ASSISTED STEERING SYSTEM
Service Precaution
WARNING: THIS VEHICLE HAS A SUPPLEMENTAL
RESTRAINT SYSTEM (SRS). REFER TO THE SRS
COMPONENT AND WIRING LOCATION VIEW IN
ORDER TO DETERMINE WHETHER YOU ARE
PERFORMING SERVICE ON OR NEAR THE SRS
COMPONENTS OR THE SRS WIRING. WHEN YOU
ARE PERFORMING SERVICE ON OR NEAR THE SRS
COMPONENTS OR THE SRS WIRING, REFER TO
THE SRS SERVICE INFORMATION. FAILURE TO
FOLLOW WARNINGS COULD RESULT IN POSSIBLE
AIR BAG DEPLOYMENT, PERSONAL INJURY, OR
OTHERWISE UNNEEDED SRS SYSTEM REPAIRS.
CAUTION: Always use the correct fastener in the
proper location. When you replace a fastener, use
ONLY the exact part number for that application.
ISUZU will call out those fasteners that require a
replacement after removal. ISUZU will also call out
the fasteners that require thread lockers or thread
sealant. UNLESS OTHERWISE SPECIFIED, do not
use supplemental coatings (Paints, greases, or other
corrosion inhibitors) on threaded fasteners or
fastener joint interfaces. Generally, such coatings
adversely affect the fastener torque and the joint
clamping force, and may damage the fastener. When
you install fasteners, use the correct tightening
sequence and specifications. Following these
instructions can help you avoid damage to parts and
systems.
Diagnosis
Since the problems in steering, suspension, wheels and
tires involve several systems, they must all be considered
when diagnosing a complaint. To identify the symptom,
always road test the vehicle first. Proceed with the follow-
ing preliminary inspections and correct any defects which
are found.
1. Inspect tires for proper pressure and uneven wear.
2. Raise vehicle on a hoist, then inspect front and rear
suspension and steering linkage for loose or
damaged parts.
3. Spin the front wheels. Inspect for out-of-round tires,
out-of-balance tires, loose and/or rough wheel
bearings.
General Diagnosis
ConditionPossible causeCorrection
Vehicle PullsMismatched or uneven tires.Replace tire.
Tires not adequately inflated.Adjust tire pressure.
Broken or sagging springs.Replace spring.
Radial tire lateral force.Replace tire.
Improper wheel alignment.Adjust wheel alignment.
Brake dragging in one wheel.Repair brake.
Loose, bent or broken front or rear
suspension parts.Tighten or replace the appropriate
suspension part(s).
Faulty shock absorbers.Replace shock absorber.
Parts in power steering valve
defective.Replace power steering unit.
Abnormal or Excessive Tire WearSagging or broken spring.Replace spring.
Tire out of balance.Balance or replace tire.
Improper wheel alignment.Check front end alignment.
Faulty shock absorber.Replace shock absorber.
Hard driving.Replace tire.
Overloaded vehicle.Replace tire and reduce load.
Tires not rotated periodically.Replace or rotate tire.
Worn or loose road wheel bearings.Replace wheel bearing.
Wobbly wheel or tires.Replace wheel or tire.
Tires not adequately inflated.Adjust the pressure.

POWER±ASSISTED STEERING SYSTEM2A±3
Condition CorrectionPossible cause
Wheel HopBlister or bump on tire.Replace tire.
Improper shock absorber operation.Replace shock absorber.
Shimmy, Shake or VibrationTire or wheel out of balance.Balance wheels or replace tire/or
wheel.
Loose wheel bearings.Replace wheel bearing.
Worn steering linkage ball joints.Replace ball joints.
Worn upper or lower end ball joints.Replace ball joints.
Excessive wheel run±out.Repair or replace wheel and/or tire.
Blister or bump on tire.Replace tire.
Excessive loaded radial run±out of
tire/wheel assembly.Replace tire or wheel.
Improper wheel alignment.Check wheel alignment.
Loose or worn steering linkage.Tighten or replace steering linkage.
Loose steering unit.Tighten steering unit.
Tires not adequately inflated.Adjust tire pressure.
Loose, bent or broken front or rear
suspension parts.Tighten or replace the appropriate
suspension parts.
Faulty shock absorber.Replace shock absorber.
Hub bearing preload misadjustment.Adjust preload.
Parts in power steering valve
defective.Replace power steering unit.
Hard SteeringBind in steering linkage ball studs,
upper or lower end ball joint.Replace ball joint.
Improper wheel alignment.Check wheel alignment.
Tire not adequately inflated.Inflate tires to proper pressure.
Bind in steering column or shaft.Repair or replace.
Improper power steering system
operation.Repair or replace.
Refer to
Power steering system
diagnosis
Too Much Play In SteeringWheel bearings worn.Replace wheel bearings.
Loose steering unit or linkage.Retighten or repair.
Worn or loose steering shaft
universal joint.Retighten or replace steering shaft.
Worn steering linkage ball joints.Replace ball joints.
Worn upper or lower end ball joints.Replace ball joints.
Poor Steering Wheel ReturnabilityBind in steering linkage ball joints.Replace ball joints.
Bind in upper or lower end ball joints.Replace ball joints.
Bind in steering column and shaft.Repair or replace.
Bind in steering gear.Check and repair steering gear.
Improper wheel alignment.Adjust wheel alignment.
Tires not adequately inflated.Adjust tire pressure.
Loose steering wheel nut.Retighten.
Worn wheel bearing.Replace.

2A±4
POWER±ASSISTED STEERING SYSTEM
Condition CorrectionPossible cause
Abnormal NoiseWorn, sticky or loose upper or lower
ball joint, steering linkage ball joints
or drive axle joints.Replace.
Faulty shock absorbers.Replace.
Worn upper or lower control arm
bushing.Replace.
Loose stabilizer bar.Retighten bolts or replace bushings.
Loose wheel nuts.Tighten nuts. Check for elongated
wheel nut holes.
Replace wheel if required.
Loose suspension bolts or nuts.Retighten suspension bolts or nuts.
Broken or otherwise damaged wheel
bearings.Replace wheel bearing.
Broken suspension springs. Replace spring.
Loose steering unit. Retighten mounting bolt.
Faulty steering unit.Replace steering unit.
Wandering or Poor Steering StabilityMismatched or unevenly worn tires.Replace tire or inflate tires to proper
pressure.
Loose steering linkage ball joints.Replace ball joints.
Faulty shock absorbers.Replace shock absorber.
Loose stabilizer bar.Tighten or replace stabilizer bar or
bushings.
Broken or sagging springs.Replace spring (pairs).
Improper wheel alignment.Adjust wheel alignment.
Erratic Steering When BrakingWorn wheel bearings.Replace wheel bearings.
Broken or sagging springs.Replace spring (pairs).
Leaking caliper.Repair or replace caliper.
Warped discs.Replace brake disc.
Badly worn brake pads.Replace brake pads.
Tires are inflated unequally.Inflate tires to proper pressure.

POWER±ASSISTED STEERING SYSTEM2A±5
Power Steering System
There is some noise in all power steering systems. One
of the most common is a hissing sound when the steering
wheel is fully turned and the car is not moving. This noise
will be most evident when the steering wheel is operated
while the brakes are applied. There is no relationshipbetween this noise and steering performance. Do not
replace the valve unless the ªhissingº noise is extremely
objectionable. A replacement valve will also have a slight
noise, and is not always a cure for the condition.
Condition
Possible causeCorrection
Rattle or Chucking NoisePressure hose touching other parts
of vehicle.Adjust hose position. Do not bend
tubing by hand.
Tie rod ends loose.Tighten or replace tie rod end.
Loose steering unit mounting.Tighten steering unit mounting.
Poor Return of Steering Wheel to
Center
Improper front wheel alignment.Adjust front wheel alignment.
CenterWheel bearing worn.Replace front wheel bearing.
Tie rod end binding.Replace tie rod end.
Ball joint binding.Replace ball joint.
Tight or frozen steering shaft
bearing.Replace steering assembly.
Sticky or plugged steering unit valve.Flush or replace steering unit.
Entry of air in the power steering
system.Bleed the system.
Momentary Increase In Effort When
Turning Wheel Fast To Right or Left
High internal leakage.Repair steering gear.
Turning Wheel Fast To Right or LeftPower steering fluid level low.Replenish fluid.
Steering Wheel Surges or Jerks
When Turning Especially During
Insufficient pump pressure.Repair pump assembly.
When Turning Especially During
Parkin
gSticky steering unit valve.Flush or replace steering unit.Parking
Power steering fluid level low.Replenish fluid.
Excessive Wheel Kick Back or Loose
Steering
Air in system.Bleed hydraulic system.
SteeringTie rod end loose.Tighten tie rod end.
Wheel bearing worn.Replace wheel bearing.
Hard Steering or Lack or Power
Assist
Sticky steering unit valve.Flush or replace steering unit.
AssistInsufficient pump pressure.Repair pump assembly.
Excessive internal pump leakage.Repair pump assembly.
Excessive internal steering gear
leakage.Repair steering gear.
Power steering fluid level low.Replenish fluid.
Unstable Engine Idling or Stalling
When TurningPressure switch of the power
steering pump or its harness is faulty.Repair or replace.

2A±6
POWER±ASSISTED STEERING SYSTEM
Power Steering Pump
Foaming milky power steering fluid, low fluid level, and
possible low pressure can be caused by air in the fluid, or
loss of fluid due to internal pump leakage. Check for leak
and correct. Bleed the system. Extremely cold
temperatures will cause air bubbles in the system if thefluid level is low. If the fluid level is correct and the pump
still foams, remove the pump from the vehicle and check
housing for cracks. If the housing is cracked, replace the
pump housing.
Condition
Possible causeCorrection
Low Pressure Due to Steering PumpRelief valve sticking or inoperative.Replace relief valve.
Side plate not flat against cam ring.Replace side plate.
Extreme wear of cam ring.Replace cam ring.
Scored side plate or rotor.Replace side plate or rotor.
Vanes sticking in rotor slots.Repair or replace vanes and rotor.
Cracked or broken side plate.Replace side plate.
High internal leakage.Repair internal leakage.
Low Pressure Due to Steering GearScored housing bore.Replace housing.
Growling Noise In Steering PumpExcessive back pressure in hoses or
steering unit caused by restriction.Repair steering unit or pump.
Scored side plate or rotor.Replace side plate or rotor.
Worn cam ring.Replace cam ring.
Groaning Noise In Steering PumpAir in the fluid.Bleed hydraulic system.
Low fluid level.Replenish fluid.
Pump mounting loose.Tighten mounting bolt.
Rattling Noise In Steering PumpVanes sticking in rotor slots.Repair or replace vanes and rotor.
Vane improperly installed.Repair rotor and vane.
Swishing Noise In Steering PumpDamaged relief valve.Replace relief valve.
Whining Noise In Steering PumpScored side plate and vanes.Replace side plate and vanes.
Steering Column Lock System
ConditionPossible causeCorrection
Will Not UnlockDamaged lock cylinder.Replace lock cylinder.
Damaged park lock cable.Replace park lock cable.
Will Not LockLock spring broken or worn.Replace lock cylinder.
Damaged lock cylinder.Replace lock cylinder.
Ignition switch stuck.Repair or replace ignition switch.
Park lock cable damaged.Replace park lock cable.
Key Cannot be Removed in
ªOFF LOCKº
Ignition switch is not set correctly.Correct ignition switch.
ªOFF-LOCKºDamaged lock cylinder.Replace lock cylinder.
Faulty shift lock mechanism.Repair or replace the shift lock
mechanism.
Column
ConditionPossible causeCorrection
Noise in ColumnUniversal joint loose.Tighten joint.
Shaft lock snap ring not seated.Place snap ring in proper position.

POWER±ASSISTED STEERING SYSTEM2A±7
Turn Signal Switch
This diagnosis covers mechanical problems only. Refer
to
Turn Signal Switch in Electrical section for electrical
diagnosis.
ConditionPossible causeCorrection
Turn Signal Will Not Stay In Turn
PositionForeign material or loose parts
preventing movement of yoke.Repair or replace signal switch.
Broken or missing detent or
canceling spring.Replace signal switch.
Turn Signal Will Not CancelLoose switch mounting screws.Tighten mounting screws.
Switch or anchor bosses broken.Replace turn signal switch.
Broken, missing or out of position
detent, return or canceling spring.Replace turn signal switch.
Worn canceling cam.Replace turn signal switch.
Turn Signal Difficult To OperateTurn signal switch arm loose.Tighten arm screw.
Broken or distorted yoke.Replace turn signal switch.
Loose or misplaced springs.Replace turn signal switch.
Foreign parts and/or material.Repair turn signal switch.
Loose turn signal switch mounting
screws.Tighten mounting screws.
Turn Signal Will Not Indicate Lane
ChangeBroken lane change pressure pad or
spring hanger.Replace turn signal switch.
Broken, missing or misplaced lane
change spring.Replace turn signal switch.
Base of wire damaged.Replace turn signal switch.
Hazard Switch Cannot Be Turned OffForeign material between hazard
switch to turn signal switch body.Repair or replace hazard switch.
No Turn Signal LightsElectrical failure in chassis harness.Refer to Electrical section.
Inoperative turn signal flasher unit.Replace flasher unit.
Loose chassis harness connector.Repair loose connector.
Front or Rear Turn Signal Lights Not
FlashingBurned-out or damaged turn signal
bulb.Replace bulb.
High resistance connection to
ground at bulb socket.Repair bulb socket.
Loose chassis harness connector.Repair loose connector.

2A±8
POWER±ASSISTED STEERING SYSTEM
General Description
The hydraulic power steering system consists of a pump,
an oil reservoir, a steering unit, a pressure hose and a
return hose.
Power Steering Unit
A02RW001
The power steering unit is rack and pinion type.
The toe±in angle can be adjusted by turning the rod on
each side.
The steering housing cannot be disassembled.
Hydraulic Pump
A02RX002

POWER±ASSISTED STEERING SYSTEM2A±9
The hydraulic pump is vane-type design. The submerged
pump has housing and internal parts that are inside the
reservoir and operate submerged in oil. There are two
bore openings at the rear of the pump housing. The larger
opening contains the cam ring, pressure plate, thrust
plate, rotor and vane assembly, and end plate. The
smaller opening contains the pressure line union, flow
control valve and spring.
The flow control orifice is part of the pressure line union.
The pressure relief valve inside the flow control valve
limits the pump pressure.Pressure Switch
When hydraulic pressure reaches 3430 kPa (500 psi), the
pressure switch of the power steering pump closes
causing the Powertrain Control Module (PCM) to actuate
the throttle valve, which increases the engine rpm to
prevent the overload-induced engine speed slow down.
The switch opens when hydraulic pressure drops to 2940
kPa (430 psi).
Steering Column
431RY00009
WARNING: T O AV O I D D E P L O Y M E N T W H E N
TROUBLE-SHOOTING THE SRS SYSTEM, DO NOT
USE ELECTRICAL TEST EQUIPMENT, SUCH AS
BATTERY-POWERED OR A/C-POWERED
VOLT-METER, OHMMETER, ETC., OR ANY TYPE OF
ELECTRICAL EQUIPMENT OTHER THAN
SPECIFIED IN THIS MANUAL. DO NOT USE A
NON-POWERED PROBE-TYPE TESTER.INSTRUCTION IN THIS MANUAL MUST BE
FOLLOWED CAREFULLY, OTHERWISE PERSONAL
INJURY MAY RESULT.
When servicing a vehicle equipped with Supplemental
Restraint System, pay close attention to all WARNINGS
and CAUTIONS.
For detailed explanation about SRS, refer to
Restraints
section.

2A±10
POWER±ASSISTED STEERING SYSTEM
The steering column has three important features in
addition to the steering function:
1. The column is energy absorbing, designed to
compress in a front-end collision to minimize the
possibility of injury to the driver of the vehicle.
2. The ignition switch and lock are mounted
conveniently on the column.
3. With the column mounted lock, the ignition and
steering operation can be locked to prevent theft of
the vehicle.The column can be disassembled and reassembled.
However, to insure the energy absorbing action, use only
the specified screws, bolts and nuts as designated, and
tighten them to the specified torque.
Handle the column with care when it is removed from the
vehicle. A sharp blow on the end of steering shaft or shift
lever, or dropping the assembly could shear or loosen the
fasteners that maintain column rigidity.
Power Steering System Test
Test Procedure
C02RW001
Legend
(1) Fluid Reservoir(2) Power Steering Unit
(3) Power Steering Pump
Test of fluid pressure in the power steering system is
performed to determine whether or not the oil pump and
power steering unit are functioning normally.
The power steering system test is used to identify and
isolate hydraulic circuit difficulties. Prior to performing
this test, the following inspections and corrections, if
necessary, must be made.

Inspect pump reservoir for proper fluid level.

Inspect pump belt for proper tension.

Inspect pump driver pulley condition. 1. Place a container under the pump to catch the fluid
when disconnecting or connecting the hoses.
2. With the engine NOT running, disconnect the
pressure hose at the power steering pump and install
power steering tester J-29877-A. The gage must be
between the shutoff valve and pump. Open the
shutoff valve.
3. Check the fluid level. Fill the reservoir with power
steering fluid, to the ªFullº mark. Start the engine,
then turn the steering wheel and momentarily hold it
against a stop (right or left). Turn the engine off and
check the connections at tester for leakage.

POWER±ASSISTED STEERING SYSTEM2A±11
4. Bleed the system. Refer to Bleeding the Power
Steering System
in this section.
5. Start the engine and check the fluid level. Add power
steering fluid if required. When the engine is at
normal operating temperature, increase engine
speed to 1500 rpm.
CAUTION: Do not leave shutoff valve fully closed
for more than 5 seconds, as the pump could become
damaged internally.
6. Fully close the shutoff valve. Record the highest
pressures.

If the pressure recorded is within 9300±9800 kPa
(1350±1420 psi), the pump is functioning within its
specifications.

If the pressure recorded is higher than 9800 kPa
(1420 psi), the valve in the pump is defective.

If the pressure recorded is lower than 9300 kPa
(1350 psi), the valve or the rotating group in the
pump is defective.
7. If the pump pressures are within specifications, leave
the valve open and turn (or have someone else turn)
the steering wheel fully in both directions. Record the
highest pressures and compare with the maximum
pump pressure recorded in step 6. If this pressure
cannot be built in either side of the power steering
unit, the power steering unit is leaking internally and
must be replaced.
8. Shut the engine off, remove the testing gauge.
9. Reconnect the pressure hose, check the fluid level
and make the needed repairs.
10. If the problem still exists, the steering and front
suspension must be thoroughly examined.
Maintenance
The hydraulic system should be kept clean and fluid level
in the reservoir should be checked at regular intervals and
fluid added when required. Refer to
Recommended
Fluids and Lubricants in General Information
section for
the type of fluid to be used and the intervals for filling.
If the system contains some dirt, flush it as described in
this section. If it is exceptionally dirty, the pump must be
completely disassembled before further usage. (The
steering unit cannot be disassembled.)
All tubes, hoses, and fittings should be inspected for
leakage at regular intervals. Fittings must be tight. Make
sure the clips, clamps and supporting tubes and hoses
are in place and properly secured.
Power steering hoses and lines must not be twisted,
kinked or tightly bent. Air in the system will cause spongy
action and noisy operation. When a hose is disconnected
or when fluid is lost, for any reason, the system must be
bled after refilling. Refer to
Bleeding the Power Steering
System
in this section.

Inspect belt for tightness.

Inspect pulley for looseness or damage. The pulley
should not wobble with the engine running.

Inspect hoses so they are not touching any other
parts of the vehicle.

Inspect fluid level and fill to the proper level.
Fluid Level
1. Run the engine until the power steering fluid reaches
normal operating temperature, about 55
C (130
F),
then shut the engine off.
2. Check the level of fluid in the reservoir.
3. If the fluid level is low, add power steering fluid as
specified in General Information to the proper level
and install the receiver cap.
4. When checking the fluid level after the steering
system has been serviced, air must be bled from the
system. Refer to
Bleeding the Power Steering
System
in this section.
Bleeding The Power Steering System
When a power steering pump or unit has been installed,
or an oil line has been disconnected, the air that has
entered the system must be bled out before the vehicle is
operated. If air is allowed to remain in the power steering
fluid system, noisy and unsatisfactory operation of the
system may result.
Bleeding Procedure
When bleeding the system, and any time fluid is added to
the power steering system, be sure to use only power
steering fluid as specified in General Information.
1. Fill the pump fluid reservoir to the proper level and let
the fluid settle for at least two minutes.
2. Start the engine and let it run for a few seconds. Do
not turn the steering wheel. Then turn the engine off.
3. Add fluid if necessary.
4. Repeat the above procedure until the fluid level
remains constant after running the engine.
5. Raise and support the front end of the vehicle so that
the wheels are off the ground.
6. Start the engine. Slowly turn the steering wheel right
and left, lightly contacting the wheel stops.
7. Add power steering fluid if necessary.
8. Lower the vehicle, set the steering wheel at the
straight forward position after turning it to its full steer
positions 2 or 3 times, and stop the engine.
9. Check the fluid level and refill as required.
10. If the fluid is extremely foamy, allow the vehicle to set
a few minutes, then repeat the above procedure.
Flushing The Power Steering System
1. Raise and support the front end of the vehicle off the
ground until the wheels are free to turn.
2. Remove the fluid return line at the pump inlet
connector and plug the connector port on the pump.
Position the line toward a large container to catch the
draining fluid.
3. While running the engine at idle, fill the reservoir with
new power steering fluid. Turn the steering wheel in
both directions. Do not contact or hold the steering
wheel to the wheel stops. This will cause the pump to
go to pressure relief mode, which may cause a
sudden fluid overflow at the reservoir.