Isuzu Amigo / Axiom / Trooper / Rodeo / VehiCross. Manual — part 1715

POWER-ASSISTED STEERING SYSTEM

2A–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 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

A02RW002

WARNING: TO AVOID DEPLOYMENT WHEN
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
ELECTRICA L 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

E nd O FCallo ut

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 “Full" 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.

Legend

(1)

Fluid Reservoir

(2)

Power Steering Unit

(3)

Power Steering Pump

POWER-ASSISTED STEERING SYSTEM

2A–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.

2A–12

POWER-ASSISTED STEERING SYSTEM

4. Install all the lines and hoses. Fill the system with

new power steering fluid and bleed the system as
described in Bleeding The Power Steering System.
Operate the engine for about 15 minutes.
Remove the pump return line at the pump inlet and
plug the connection on the pump. While refilling the
reservoir, check the draining fluid for contamination.
If foreign material is still evident, replace all lines,
disassemble and clean or replace the power
steering system components. Do not re-use any
drained power steering fluid.

Steering Wheel Free Play Inspection

430RX003

1. With the tires in the straight-ahead position, check

the amount of steering wheel play by turning the
wheel in both directions until the tires begin to
move.

NOTE: The wheel free play should be checked with the
engine running.

Free play: 0 – 30 mm (0 – 1.18in)

2. Also check the steering wheel for play and

looseness in the mount by moving it back and forth
and sideways. When test driving, check for hard
steering, steering shimmy and tendency to pull to
one side.

Front End Alignment Inspection and
Adjustment

General Description

“Front End Alignment" refers to the angular relationship
between the front wheels, the front suspension
attaching parts and the ground.
Proper front end alignment must be maintained in order
to insure efficient steering, good directional stability and
to prevent abnormal tire wear.
The most important factors of front end alignment are
wheel toe-in, wheel camber and axle caster.

Camber:

This illustration shows view from the front of the vehicle.

480RS004

Camber is the vertical tilting inward or outward of the
front wheels. When the wheels tilt outward at the top,
the camber is positive (+). When the wheels tilt inward
at the top, the camber is negative (-). The amount of tilt
measured in degrees from the vertical is called the
camber angle (1). If camber is extreme or unequal
between the wheels, improper steering and excessive
tire wear will result. Negative camber causes wear on
the inside of the tire, while positive camber causes wear
to the outside.

Caster:

This illustration shows view from the side of the vehicle.

480RS005