air suspension ISUZU AXIOM 2002 Service Service Manual

WHEEL AND TIRE SYSTEM3E±1
AXIOM
SUSPENSION
WHEEL AND TIRE SYSTEM
CONTENTS
Service Precaution 3E±1. . . . . . . . . . . . . . . . . . . . . .
General Description 3E±2. . . . . . . . . . . . . . . . . . . . .
Diagnosis 3E±3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Wheel 3E±11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Wheel and Associated Parts 3E±11. . . . . . . . . . . .
Removal 3E±11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . Installation 3E±11. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Tire 3E±12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Tire Replacement 3E±12. . . . . . . . . . . . . . . . . . . . . .
General Balance Procedure 3E±12. . . . . . . . . . . . . .
Balancing Wheel and Tire 3E±13. . . . . . . . . . . . . . . .
Main Data and Specifications 3E±14. . . . . . . . . . . . .
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.

WHEEL AND TIRE SYSTEM3E±3
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.
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 runout.Repair or replace wheel and/or tire.
Blister or bump on tire.Replace tire.
Excessive loaded radial runout 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.

3E±4WHEEL AND TIRE SYSTEM
Condition CorrectionPossible cause
Hard SteeringBind in steering linkage ball studs,
upper or lower 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 Steering
section.
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 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 pressure.
Loose steering wheel nut.Retighten.
Worn wheel bearing.Replace.
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.

WHEEL AND TIRE SYSTEM3E±5
Condition CorrectionPossible cause
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.
Low or Uneven Trim HeightBroken or sagging springs.Replace springs (In pairs).
Vehicle overloaded.Reduce load.
Incorrect springs.Adjust or replace torsion bar.
Suspension BottomsVehicle overloaded. Reduce load.
Faulty shock absorber.Replace shock absorber.
Incorrect, broken or sagging springs.Replace springs.
Body LeansLoose stabilizer bar.Tighten stabilizer bar bolts or replace
bushings.
Faulty shock absorber, struts or
mounting.Replace shock absorber.
Broken or sagging springs.Replace springs (In pairs).
Vehicle overloaded.Reduce load.
Cupped TiresWorn wheel bearings.Replace wheel bearing.
Excessive tire or wheel run out.Replace tire or wheel.
Worn ball joints.Replace ball joints.
Tire out of balance.Adjust tire balance.
Irregular and Premature Wear
480RS001
Irregular and/or premature wear has many causes.
Some of them are incorrect inflation pressures, lack of tire
rotation, poor driving habits or improper wheel alignment.
Incorrect inflation is common cause of tire premature
wear.NOTE: Due to their design, radial tires tend to wear faster
in the shoulder area, particularly on the front tires. This
makes regular rotation especially necessary. After
rotation, be sure to check wheel nut torque, and set tire
pressures.

INTELLIGENT SUSPENSION3F±1
AXIOM
SUSPENSION
INTELLIGENT SUSPENSION CONTROL
CONTENTS
Service Precaution 3F±2. . . . . . . . . . . . . . . . . . . . . .
General Description 3F±2. . . . . . . . . . . . . . . . . . . . .
PIN ASSIGNMENT TABLE 3F±4. . . . . . . . . . . . .
System Components 3F±4. . . . . . . . . . . . . . . . . . .
Control Unit 3F±4. . . . . . . . . . . . . . . . . . . . . . . . . . .
Actuator 3F±4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Adjustable Damping Force Shock Absorber 3F±4
Warning Lamp 3F±4. . . . . . . . . . . . . . . . . . . . . . . .
Vertical G-Sensor 3F±5. . . . . . . . . . . . . . . . . . . . . .
Lateral G-Sensor 3F±5. . . . . . . . . . . . . . . . . . . . . .
Acronyms and Abbreviations 3F±5. . . . . . . . . . . .
General Diagnosis 3F±5. . . . . . . . . . . . . . . . . . . . . . .
General Information 3F±5. . . . . . . . . . . . . . . . . . . .
Service Precautions 3F±5. . . . . . . . . . . . . . . . . . .
Computer System Service Precautions 3F±5. . .
General Service Precautions 3F±5. . . . . . . . . . . .
Parts Handling 3F±5. . . . . . . . . . . . . . . . . . . . . . . .
FLASHING CODES 3F±6. . . . . . . . . . . . . . . . . . . .
CLEAR DTC 3F±7. . . . . . . . . . . . . . . . . . . . . . . . . .
INTERMITTENT CONDITIONS 3F±8. . . . . . . . .
BULB CHECK 3F±8. . . . . . . . . . . . . . . . . . . . . . . . .
DTC CHECK 3F±8. . . . . . . . . . . . . . . . . . . . . . . . . .
Connector List 3F±14. . . . . . . . . . . . . . . . . . . . . . . .
Diagnostic Trouble Code (DTC)
Identification 3F±16. . . . . . . . . . . . . . . . . . . . . . . . .
DTC2 Actuator Coil Over Current 3F±17. . . . . . . . . .
Circuit Description 3F±17. . . . . . . . . . . . . . . . . . . . .
Diagnostic Aids 3F±17. . . . . . . . . . . . . . . . . . . . . . . .
DTC3 Actuator Coil/Position Sensor Open
Circuit or Short 3F±19. . . . . . . . . . . . . . . . . . . . . . . . .
Circuit Description 3F±19. . . . . . . . . . . . . . . . . . . . . Diagnostic Aids 3F±19. . . . . . . . . . . . . . . . . . . . . . . .
DTC4 G-Sensor Open Circuit or Short 3F±22. . . . .
Circuit Description 3F±22. . . . . . . . . . . . . . . . . . . . .
Diagnostic Aids 3F±22. . . . . . . . . . . . . . . . . . . . . . . .
DTC5 Vehicle Speed Sensor Open Circuit
or Short 3F±23. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Circuit Description 3F±23. . . . . . . . . . . . . . . . . . . . .
Diagnostic Aids 3F±23. . . . . . . . . . . . . . . . . . . . . . . .
DTC6 Stop Lamp Switch Open Circuit
or Short 3F±25. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Circuit Description 3F±25. . . . . . . . . . . . . . . . . . . . .
Diagnostic Aids 3F±25. . . . . . . . . . . . . . . . . . . . . . . .
DTC7 Engine Speed Signal Open Circuit
or Short 3F±27. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Circuit Description 3F±27. . . . . . . . . . . . . . . . . . . . .
Diagnostic Aids 3F±27. . . . . . . . . . . . . . . . . . . . . . . .
DTC9 Control Unit Abnormality 3F±28. . . . . . . . . . . .
Control Unit 3F±32. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Removal 3F±33. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation 3F±33. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Front Actuator 3F±34. . . . . . . . . . . . . . . . . . . . . . . . . .
Removal 3F±35. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Inspection and Repair 3F±35. . . . . . . . . . . . . . . . . . . .
Installation 3F±35. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Rear Shock Absorber 3F±36. . . . . . . . . . . . . . . . . . . .
Removal 3F±37. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Inspection and Repair 3F±37. . . . . . . . . . . . . . . . . . . .
Installation 3F±37. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3F±2INTELLIGENT SUSPENSION
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.
General Description
Intellignet suspension control uses a microcomputer as a
control unit to judge running conditions including engine
revolution from Powertrain Control Module, vehicle speed
from vehicle speed sensor, a brake switch signal, and
vertical and lateral G-sensor signal, then sets optimum
damping force so that best running stability can be
achieved.

INTELLIGENT SUSPENSION3F±5
Vertical G-Sensor
Front G-sensors installed inside front actuators and the
rear G-sensor installed on the rear left frame side detect
the vehicle vertical gravity and send a signal to the Control
Unit.
Lateral G-Sensor
The G-sensor installed inside the Control Unit detects the
vehicle turning speed and sends a signal to the Control
Unit.
Acronyms and Abbreviations
Several acronyms and abbreviations are commonly used
throughout this section:
BATT
Battery
DLC
Data Link Connector
DTC
Diagnostic Trouble Code
FL
Front Left
FR
Front Right
GND
Ground
HARN
Harness
IG
Ignition
PCM
Powertrain Control Module
RL
Rear Left
RR
Rear Right
SW
Switch
W/L
Warning Lamp
Vout
Voltage output
General Diagnosis
General Information
Intelligent Suspension Control troubles can be classified
into two types, those which can be detected by the
warning lamp and those which can be detected as a
vehicle abnormality by the driver.
In either case, locate the fault in accordance with
theªBASIC DIAGNOSTIC FLOWCHARTº and repair.
Please refer to
Section 3 for the diagnosis of mechanical
troubles such as abnormal noise, vehicle pulls, excessive
tire wear, wheel hop and shimmy, shake or vibration.
Service Precautions
Required Tools and Items:

Box Wrench

Special Tool
Some diagnosis procedures in this section require the
installation of a special tool.
J-39200 High Impedance Multimeter
When circuit measurements are requested, use a
circuit tester with high impedance.
Computer System Service Precautions
The Intelligent Suspension Control interfaces directly
with the Control Unit which is a control computer that is
similar in some regards to the Powertrain Control Module.
These modules are designed to withstand normal current
draws associated with vehicle operation. However care
must be taken to avoid overloading any of the Control Unit
circuits. In testing for opens or shorts, do not ground or
apply voltage to any of the circuits unless instructed to do
so by the appropriate diagnostic procedure. These
circuits should only be tested with a high impedance
multimeter (J-39200) or special tools as described in this
section. Power should never be removed or applied to
any control module with the ignition in the ªONº
position.Before removing or connecting battery cables,
fuses or connectors, always turn the ignition switch to
theªOFFº position.
General Service Precautions
The following are general precautions which should be
observed when servicing and diagnosing the Intelligent
Suspension Control and/or other vehicle systems. Failure
to observe these precautions may result in Intelligent
Suspension Control damage.

If welding work is to be performed on the vehicle using
an electric arc welder, the Control Unit connectors
should be disconnected before the welding operation
begins.

The Control Unit connectors should never be
connected or disconnected with the ignitionªONº.
Parts Handling
Be careful when handling the actuator, control unit, or
G-sensor. They should not be dropped or thrown,
because the semi-conductor G-sensor tip damage may
result.

3F±6INTELLIGENT SUSPENSION
FLASHING CODES
1. ON BOARD DIAGNOSIS (SELF-DIAGNOSIS)
1. The Control Unit conducts a self-test of most of the
wiring and components in the system each time the
key is turned ON. If a fault is detected the Control
Unit will store a Diagnostic Trouble Code (DTC) in
memory. It's a number that corresponds to a
specific problem.
2. When the problem detected is important: the
warning lamp turns on until the fault is repaired and
the Control Unit memory is cleared.
2. DIAGNOSTIC TROUBLE CODES (DTC)
1. DTC can be expressed by flashing times of warning
lamp by shorting together terminals 3 and 4 or 5 of
the Diagnosis Connector (C-39) located left side of
instrument panel.
350R200002
Normal
F03RY00001
Abnormal
F03R200001
Legend
(1) Diagnostic Trouble Code 2
(2) Diagnostic Trouble Code 3

3F±18INTELLIGENT SUSPENSION
DTC2 Actuator Coil Over Current (Cont'd)
StepNo Ye s Value(s) Action
12Replace the rear shock absorber RL.
ÐGo to Step 16Ð
13If all steps are correct, check the continuity between the
control unit connector C±46 terminal 1 and connector
terminal C46±4, C46±17, C46±5, C46±18, C46±6,
C46±19, C46±7, C46±20, C46±8, C46±21, C46±9,
C46±22, C46±10, C46±23, C46±11, and C46±24.
Is there continuity?
ÐGo to Step 15Go to Step 14
14Repair the circuit.
ÐGo to Step 16Ð
15Replace the control unit.
ÐGo to Step 16Ð
161. Reconnect all components, ensure all components
are properly mounted.
2. Clear the DTC.
Was this step finished?
Ð
Go to ªBasic
Diagnosis
Flowº.
Go to Step 16

INTELLIGENT SUSPENSION3F±19
DTC3 Actuator Coil/Position Sensor Open Circuit or Short
Circuit Description
The A, B, C, and D are the actuator motor coil terminals.
DC 12V driving voltage is applied between terminals A
and C and terminals B and D so that the shock absorber
oil valves are rotated at every 7.5
step feed.
The PSW is actuator position signal and detects relative
angles between the piston±rod and the control-rod. The
actuator outputs the PSW to the control unit.
Diagnostic Aids

Inspect the wiring for poor electrical connections
between the control unit 16 way connector and the
actuator connectors. Look for possible bent, backed
out, deformed, or damaged terminals. Check for
weak terminal tension as well.
Also check for a chafed wire that could short to bare
metal or other wiring. Inspect for a broken wire inside
the insulation.

When diagnosing for a possible intermittent short or
open condition, move the wiring harness while
observing test equipment for a change.
DTC3 Actuator Coil/Position Sensor Open Circuit or Short
StepActionValue(s)Ye sNo
11. Turn off the starter switch.
2. Disconnect the actuator connectors C±46, C±31,
C±9, F±8, and F±7.
Is there continuity between the connector C±9
terminals 1 and 2?
ÐGo to Step 2Go to Step 3
2Is there continuity between the connector C±9
terminals 3 and 4?
ÐGo to Step 4Go to Step 3
3Replace the actuator FR.
ÐGo to Step 4Ð
4Is there continuity between the connector C±31
terminals 1 and 2?
ÐGo to Step 5Go to Step 6
5Is there continuity between the connector C±31
terminals 3 and 4?
ÐGo to Step 7Go to Step 6
6Replace the actuator FL.
ÐGo to Step 7Ð
7Is there continuity between the connector F±7
terminals 3 and 4?
ÐGo to Step 8Go to Step 9
8Is there continuity between the connector F±7
terminals 7 and 8?
ÐGo to Step 10Go to Step 9
9Replace the rear shock absorber RR.
ÐGo to Step 10Ð
10Is there continuity between the connector F±8
terminals 3 and 4?
ÐGo to Step 11Go to Step 12
11Is there continuity between the connector F±8
terminals 7 and 8?
ÐGo to Step 13Ð
12Replace the rear shock absorber RL.
ÐGo to Step 13Ð
13Is there continuity between the connector C±9 terminal
1 and connector C±46 terminal 4?
ÐGo to Step 14Go to Step 15
14Is there continuity between the connector C±9 terminal
3 and connector C±46 terminal 17?
ÐGo to Step 16Go to Step 15
15Repair the circuit.
ÐGo to Step 16Ð