Isuzu Amigo / Axiom / Trooper / Rodeo / VehiCross. Manual - part 570

POWER ASSISTED SYSTEM

2A–9

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 tempera-
tures will cause air bubbles in the system if the fluid level

is low.  If the fluid level is correct and the pump still foams,
remove the pump from the vehicle and check the housing
for cracks.  If the housing is cracked, replace the pump
housing.

Condition

Possible cause

Correction

Low Pressure Due to Steering Pump

Relief 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 Gear

Scored housing bore.

Replace housing.

Growling Noise In Steering Pump

Excessive 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 Pump

Air in the fluid.

Bleed hydraulic system.

Low fluid level.

Replenish fluid.

Pump mounting loose.

Tighten mounting bolt.

Rattling Noise In Steering Pump

Vanes sticking in rotor slots.

Repair or replace vanes and rotor.

Vane improperly installed.

Repair rotor and vane.

Swishing Noise In Steering Pump

Damaged relief valve.

Replace relief valve.

Whining Noise In Steering Pump

Scored side plate and vanes.

Replace side plate and vanes.

Steering Column Lock System

Condition

Possible cause

Correction

Will Not Unlock

Damaged lock cylinder.

Replace lock cylinder.

Damaged park lock cable.

Replace park lock cable.

Will Not Lock

Lock 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

Ignition switch is not set correctly.

Correct ignition switch.

“OFF-LOCK”

Damaged lock cylinder.

Replace lock cylinder.

Faulty shift lock mechanism.

Repair or replace the shift lock
mechanism.

Column

Condition

Possible cause

Correction

Noise in Column

Universal joint loose.

Tighten joint.

Shaft lock snap ring not seated.

Place snap ring in proper position.

2A–10

POWER ASSISTED SYSTEM

Turn Signal Switch

This diagnosis covers mechanical problems only. Refer
to  Turn Signal Switch in Electrical section for electrical
diagnosis.

Condition

Possible cause

Correction

Turn Signal Will Not Stay In Turn
Position

Foreign 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 Cancel

Loose 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 Operate

Turn 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
Change

Broken 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 Off

Foreign material between hazard
switch to turn signal switch body.

Repair or replace hazard switch.

No Turn Signal Lights

Electrical 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
Flashing

Burned-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.

POWER ASSISTED SYSTEM

2A–11

Power Steering System Test

Test Procedure

F02RX001

Legend

(1) Bolt (M16 

×

 1.5)

(2) Hose (Vehicle Side)

(3) To Power Steering Gear
(4) To 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 the method used to
identify and isolate hydraulic circuit difficulties.  Prior to
performing this test, the following inspections and
corrections, if necessary, must be made.

D

Inspect pump reservoir for proper fluid level.

D

Inspect pump belt for proper tension.

D

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 gauge 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.

4. Bleed the system.  Refer to Bleeding the Power

Steering System in this section.

5. Start the engine and check the pump 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.

D

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

D

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

D

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
gear, the power steering gear is leaking internally and
must be disassembled and repaired.

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.

2A–12

POWER ASSISTED SYSTEM

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, both the pump and
the gear must be completely disassembled before further
usage.
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.

D

Inspect belt for tightness.

D

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

D

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

D

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 gear 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.

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.