2002 ISUZU AXIOM ECU

3C±2FRONT SUSPENSION
General Description
The front suspension is designed to allow each wheel to
compensate for changes in the road surface level without
greatly affecting the opposite wheel. Each wheel is
independently connected to the frame by a steering
knuckle, ball joint assemblies, and upper and lower
control arms. The front wheels are held in proper
relationship to each other by two tie-rods which are
connected to steering arms on the knuckles, and to a
steering unit.
All models have a front suspension system consisting of
control arms, stabilizer bar, shock absorber and a torsion
bar. The front end of the torsion bar is attached to the
lower control arm. The rear of the torsion bar is mounted
into a height control arm at the crossmember. Vehicle trim
height is controlled by adjusting this arm.
Shock absorbers are mounted between the brackets on
the frame and the lower control arms. The lower portion ofeach shock absorber is attached to the lower control arm.
The upper portion of each shock absorber extends
through a frame bracket and is secured with two rubber
bushings, two retainers and a nut.
Ball joint assemblies are bolted to the outer end of the
upper and lower control arm and are attached to the
steering knuckle.
The inner ends of the upper control arm have pressed in
bushings. Bolts, passing through the bushing, attach the
control arm to the frame. The inner ends of the lower
control arm are attached to the frame by bolts passing
through the bushings.
Side roll of the front suspension is controlled by a spring
steel stabilizer bar. It is mounted in rubber bushings,
which are held to the frame by brackets. The ends of the
stabilizer bar are connected to the lower control arms by
links.
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.

DIFFERENTIAL (FRONT) 4A1±6
Removal
1. Jack up the vehicle and support it using jack stand.
2. Remove the tire and wheel.
3. Remove the stone guard.
4. Remove the brake caliper fixing bolt and hang the
caliper. Refer to
Disc Brakes in Brake section.
5. Remove the antilock brake system speed sensor.
Refer to
Front Wheel Speed Sensor in Brake section.
6. Remove the hub and disc assembly.
Refer to
Front Hub and Disc in this section.
7. Remove the propeller shaft, refer to
Front Propeller
Shaft
in this section.
8. Loosen the height control arm of the torsion bar, then
remove the torsion bar from lower control arm.
Refer to
Torsion Bar in Suspension section.
9. Remove the suspension crossmember.
10. Remove the lower nut (1) of the stabilizer link.
11. Remove the lower bolt and nut (2) of the shock
absorber.
412RW057
12. Remove the tie-rod end from the knuckle. Refer to
Power Steering Unit in Steering Section.
13. Disconnect the hose of the shift on the fly.
14. Disconnect the actuator connector.
15. Remove the bolts and nuts of the lower control arm
(Frame side), then disconnect the lower control arm
from frame.
16. Disconnect between the right side upper control arm
and the knuckle, then remove the knuckle with lower
control arm.CAUTION: When removing the knuckle, be careful
not to damage the oil seal inside of the knuckle.
410RW008
17. Support the differential case by the jack.
18. Remove the front axle mounting bolts and nuts, lower
the jack slowly. Remove the left side drive shaft end
from the knuckle, then lower the axle assembly from
the vehicle.
CAUTION:
1. Make sure the axle assembly is supported
securely when performing repairs.
2. Do not damage the power steering unit when
performing the repairs.
3. Do not damage the shift±on±the fly hose bracket
when performing the repairs.
Installation
1. Support the differential case with a jack.
2. Jack up the front drive axle assembly, install the left
side drive shaft to the knuckle, then install the mount
bolts and nuts.
CAUTION:
1. Do not damage the power steering unit when
performing the repairs.
2. Do not damage the shift±on±the fly hose bracket
when performing the repairs.
3. When installing the drive shaft to the knuckle, be
careful not to damage the oil seal inside of the
knuckle.

DIFFERENTIAL (FRONT) 4A1±22
4. Install cross pin.

Be sure to install the cross pin so that it is in
alignment with the lock pin hole in the differential
cage.
425RS049
5. Install lock pin. After lock pin installation, stake the
cage to secure the lock pin.
6. Install ring gear and tighten the bolts in diagonal
sequence as illustrated.
Torque: 108 N´m (80 lb ft)
NOTE: Discard used bolts and install new ones.
415RS016

4A2±2DIFFERNTIAL (REAR)
General Description
The rear axle assembly is of the semi±floating type in
which the vehicle weight is carried on the axle housing .
The center line of the pinion gear is below the center line
of the ring gear (hypoid drive).
All parts necessary to transmit power from the propeller
shaft to the rear wheels are enclosed in a salisbury type
axle housing (a carrier casting with tubes pressed and
welded into the carrier). A removable aluminum cover at
the rear of the axle housing permits rear axle service
without removal of the entire assembly from the vehicle.
The 8.9 inch ring gear rear axle uses a conventional ring
and pinion gear set to transmit the driving force of the
engine to the rear wheels. This gear set transfers this
driving force at a 90 degree angle from the propeller shaft
to the drive shafts.
The axle shafts are supported at the wheel end of the
shaft by a roller bearing.
The pinion gear is supported by two tapered roller
bearings. The pinion depth is set by a shim pack located
between the gear end of the pinion and the roller bearing
that is pressed onto the pinion. The pinion bearing
preload is set by crushing a collapsible spacer between
the bearings in the axle housing.
The ring gear is bolted onto the differential case with 10
bolts.
The differential case is supported in the axle housing by
two tapered roller bearings. The differential and ring gear
are located in relationship to the pinion by using selective
shims and spacers between the bearing and the
differential case. To move the ring gear, shims are deleted
from one side and an equal amount are added to the other
side. These shims are also used to preload the bearings
which are pressed onto the differential case. Two bearing
caps are used to hold the differential into the rear axle
housing.
The differential is used to allow the wheels to turn at
different rates of speed while the rear axle continues to
transmit the driving force. This prevents tire scuffing
when going around corners and prevents premature wear
on internal axle parts.
The rear axle is sealed with a pinion seal, a seal at each
axle shaft end, and by a liquid gasket between the rear
cover and the axle housing.
Limited Slip Differential (LSD)
The axle assembly may be equipped with an limited slip
differential (LSD). It is similar to the standard differential
except that part of the torque from the ring gear is
transmitted through clutch packs between the side gears
and differential case.
The LSD construction permits differential action when
required for turning corners and transmits equal torque to
both wheels when driving straight ahead. However, when
one wheel tries to spin due to a patch of ice, etc., the
clutch packs automatically provide more torque to the
wheel which is not trying to spin.
In diagnosing customer complaints, it is important to
recognize two things:
1. If, both wheels slip, with unequal traction, the LSD
has done all it can possibly do.
2. In extreame cases of differences in traction, the
wheel with the least traction may spin after the LSD
has transferred as much torque as possible to the
non-slipping wheel.
Limited Slip Differntials impose additional requirements
on lubricants, and require a special lubricant or lubricant
additive. Use 80W90 GL±5 LSD lubricant.
Rear Axle Identification
The Bill of Material and build date information(1) is
stamped on the right axle tube on the rearward side.
The axle ratio is identified by a tag(3) which is secured by
a cover bolt. If the axle has limited-slip differntial, it also
will be identified with a tag(2) secured by a cover bolt.
425RX001

4A2±26DIFFERNTIAL (REAR)
Disassembly
1. Remove lock pin using a small drift.
425RS098
2. Remove the differential shaft by using a soft metal rod
and a hammer.
425RS043
3. Remove pinion mate gear and thrust washer.
4. Remove side gear and thrust washer.
Inspection and Repair
Make necessary correction or parts replacement if wear,
damage, corrosion or any other abnormal condition are
found through inspection.
Check the following parts.

Ring gear, pinion gear

Bearing

Side gear, pinion mate gear, differential shaft

Differential case, carrier

Thrust washer

Oil seal
Reassembly
1. Install side gear with thrust washer.
2. Install the pinion mate gear with thrust washer by
engaging it with the side gears while turning both
pinion mate gears simultaneously in the same
direction.
425RS048
3. Install differential shaft.
1. Be sure to install the differential shaft so that it is in
alignment with the lock pin hole in the differential
case.
425RS049
4. Install lock pin.
After lock pin installation, stake the case to secure the
lock pin.

4B2±1
DRIVE LINE CONTROL SYSTEM (TOD)
AXIOM
DRIVELINE/AXLE
DRIVELINE CONTROL SYSTEM (TOD)
CONTENTS
Service Precaution 4B2±1. . . . . . . . . . . . . . . . . . . . . .
General Description 4B2±2. . . . . . . . . . . . . . . . . . . . .
Transfer Position and Drive Mode 4B2±2. . . . . . . .
TOD Control 4B2±3. . . . . . . . . . . . . . . . . . . . . . . . . .
TOD Indicator Control 4B2±3. . . . . . . . . . . . . . . . . .
Abbreviations 4B2±3. . . . . . . . . . . . . . . . . . . . . . . . .
System Components 4B2±4. . . . . . . . . . . . . . . . . . . .
Parts Location 4B2±4. . . . . . . . . . . . . . . . . . . . . . . .
Front and Rear Speed Sensors 4B2±5. . . . . . . . . .
Electromagnetic Coil 4B2±5. . . . . . . . . . . . . . . . . . .
Multi Plate Disk Clutch Pack 4B2±5. . . . . . . . . . . .
Mechanical Lock Sleeve 4B2±5. . . . . . . . . . . . . . . .
High-Low Planetary Gear Set 4B2±6. . . . . . . . . . .
4H and 4L Switch 4B2±6. . . . . . . . . . . . . . . . . . . . . .
Transfer Connector (12-pin type) 4B2±6. . . . . . . .
Transfer Connector (8-pin type) 4B2±6. . . . . . . . .
TOD Indicator Lamps
(on the instrument panel) 4B2±7. . . . . . . . . . . . . .
Check Lamp 4B2±7. . . . . . . . . . . . . . . . . . . . . . . . . .
TOD ECU 4B2±8. . . . . . . . . . . . . . . . . . . . . . . . . . . .
High-Low Shift Motor 4B2±9. . . . . . . . . . . . . . . . . . .
Motor Position and Encoder Position Code 4B2±10
Encode Position Plate 4B2±10. . . . . . . . . . . . . . . . . .
Shift High Range and Low Range 4B2±10. . . . . . . . Functions of TOD Switch and Indicator
Lamp 4B2±11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
TOD Switch and Indication of Drive Mode 4B2±11.
Check Lamp 4B2±13. . . . . . . . . . . . . . . . . . . . . . . . . .
Diagnosis 4B2±14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
General Information Diagnosis 4B2±14. . . . . . . . . .
Self-diagnosis 4B2±14. . . . . . . . . . . . . . . . . . . . . . . . .
Precautions on Diagnosis 4B2±16. . . . . . . . . . . . . . .
Basic Diagnostic Flow Chart 4B2±18. . . . . . . . . . . . . .
Parts Location 4B2±19. . . . . . . . . . . . . . . . . . . . . . . . . .
Circuit Diagram 4B2±20. . . . . . . . . . . . . . . . . . . . . . . . .
Connector List 4B2±24. . . . . . . . . . . . . . . . . . . . . . . . . .
Checking Failed Pin 4B2±26. . . . . . . . . . . . . . . . . . . . .
Connector Pin Assignment 4B2±26. . . . . . . . . . . . . .
Reference 4B2±28. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Checking Failed TOD Control Unit Pin 4B2±30. . . . .
Tech 2 Scan Tool 4B2±32. . . . . . . . . . . . . . . . . . . . . .
Getting Started 4B2±33. . . . . . . . . . . . . . . . . . . . . . . .
Operating Procedure 4B2±33. . . . . . . . . . . . . . . . . . .
Diagnostic Trouble Codes 4B2±35. . . . . . . . . . . . . . . .
Diagnosis from Trouble Codes 4B2±36. . . . . . . . . . . .
Trouble Diagnosis Depending on The Status
of TOD Indicator 4B2±67. . . . . . . . . . . . . . . . . . . . . . . .
Diagnosis from Symptom 4B2±102. . . . . . . . . . . . . . . . .
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.

DRIVE LINE CONTROL SYSTEM (TOD) 4B2±2
General Description
412R200008
TOD (Torque on Demand) system is traction state control
system to vehicle.
Transfer Position and Drive Mode
Three drive modes can be selected through operation of
TOD switch and transfer lever.
Transfer Position
TOD SWITCHModeDrive mode
HIGH2HRWDRear wheel drive
TOD4WD
(HIGH)Electronically controlled torque split
four wheel drive
LOW4L4WD
(LOW)Low-speed mechanical lock-up four
wheel drive
The electronic control unit (ECU) judges the signals from
the TOD switch and controls the transfer drive mode and
shift-on-the-fly system status.

DRIVE LINE CONTROL SYSTEM (TOD) 4B2±8
TOD ECU
This control unit is mounted to the clutch pedal position
via a special bracket.
826R200019
Legend
(1) Brake Pedal Bracket