1998 ISUZU TROOPER oil pressure

4A2A±28
DIFFERENTIAL (REAR 220mm)
Legend
(7) Fitting section with the case.
(8) Face contacting the inner surface of the
differential case.
Repair burrs and nicks using an oil stone.
(9) Sliding surface with the side gear or case.
(11) Contact surface with spring disc.
Measure the Deformation of the friction disc & plate.
Limit: 0.08 mm (0.003 in)
425RS061
Measure the wear of the friction plate & disc
Limit(A±B): 0.1 mm (0.004 in)
Remarks:
A=Inner or outer projections
B=Sliding surface subjected to abrasion
425RS062
Measure the wear of the thrust washer
Limit: 1.3 mm (0.05 in)
425RS063
Reassembly
Adjust the clearance between the friction disc and plate.
1. Measuring the depth of the differential cage.
Standard (A±B): 80.58 mm (3.17 in)
(C): 10.58 mm (0.41 in)
425RS064
2. Measuring the overall length of the pressurering,
friction disc and friction plate.

Mount the pinion shaft in the pressurering and then
install the friction disc & plate.

4A2A±30
DIFFERENTIAL (REAR 220mm)
3. After measuring dimensions of each of the above
sections, proceed with the adjustment in the following
manner:
Adjust the clearance to satisfy the equation below.
{(F ± B) + G ± H}=0.05 ± 0.20 mm
Also, select the thrust washers so that the
dimensional difference between the back surfaces of
the left and right pressure rings to the thrust washers
is 0.05mm or less.
Thickness : 1.5mm (0.059 in)
1.6 mm(0.063 in)
1.7 mm(0.067 in)
NOTE: When assembling the parts, apply recommended
gear oil sufficiently to each of the parts, especially, to the
contact surfaces and sliding surfaces.
1. Install Differential cage B.
2. Install Thrust washer.
3. Install Spring disc.

When assembling the spring disc, make sure the
mounting direction is correct as shown in figure.
425RS068
Legend
(1) Friction Plate
(2) Spring Disc
(3) Friction Disc
4. Inatall Spring disc.
5. Inatall Friction plate.
6. Inatall Friction disc.
7. Inatall Friction plate.
8. Inatall Friction disc.
9. Inatall Pressure ring.
10. Inatall Side gear.
11. Inatall Pinion and pinion shaft.
12. Inatall Side gear.
13. Inatall Pressure ring.
14. Inatall Friction disc.15. Inatall Friction plate.
16. Inatall Friction disc.
17. Inatall Friction plate.
18. Inatall Spring disc.

When assembling the spring disc, make sure the
mounting direction is correct.
19. Inatall Spring disc.
20. Inatall Thrust washer.
21. Inatall Differential cage A.
22. Inatall Screw.

Matching the guide marks of the differential cages A
and B, tighten the screws evenly in the diagonal
order.
425RS055

4A2B±16DIFFERENTIAL (REAR 244mm)
4. Place the shim (1) on the drive pinion, then install the
inner bearing (2) onto the pinion by using installer
5±8840±2574±0 and a press .
NOTE: Do not apply pressure to the roller cage. Apply
pressure only to the inner race.
425RW061
5. Install collapsible spacer. Discard the used
collapsible spacer and install a new one.
6. Install drive pinion shaft assembly.
7. Install outer bearing and oil seal slinger.
8. Use oil seal installer 5±8840±2165±0 to install a new
oil seal that has grease on seal lip.
415RW029
9. Install flange assembly.10. Install flange nut and washer.
1. Apply lubricant to the pinion threads.
2. Using the pinion flange holder 5±8840±0133±0,
tighten the nut only enough to remove the shaft
end play.
NOTE: Discard used flange nut and install new one.
415RW006
3. Adjust pinion bearing preload.
a. Measure the bearing preload by using a torque
meter and note the scale reading required to
rotate the flange.
b. Continue tightening flange nut until the specified
starting torque is obtained.
Starting torque: 1.1±1.6 N´m (11±16kg´cm/10±14
lb in)
NOTE:
a. Do not overtighten or loosen and then retighten the
nut.
b. Pinion nut torque should be in the range of
298±380 N´m (30.4±38.8kg´m/220±281 Ib ft).
425RW018

4B2±5 DRIVE LINE CONTROL SYSTEM (TOD)
Front and Rear Speed Sensors
The sensors are built in the transfer case, detect the
rotation of rotors directly coupled to the propeller shafts.
Thirty rectangular pulses are output per one rotation of
the propeller shaft.
261RW045
Electromagnetic Coil
Receives the duty signals from the TOD control unit and
controls the pressing force of the clutch pressure cam.
261RW044
Multi Plate Disk Clutch Pack
Transmits the torque determined by the clutch pressing
force to the front propeller shaft via the front drive chain.
262RW029
Mechanical Lock Sleeve
Couples the front and rear propeller shaft mechanically
when the transfer shaft is in the 4L position.
262RW028

DRIVE LINE CONTROL SYSTEM (TOD) 4B2±88
StepActionYe sNo
1Are the front and rear tires in specified size?
Go to Step 2
Replace the tires
with specified
ones, and service
the new tires.
Go to Step 16
2Is the tire pressure correct?
Go to Step 3
Replace the tires
with specified
ones, and service
the new tires.
Go to Step 16
3Are the tires free from abnormal wear?
Go to Step 4
Replace the tires
with specified
ones, and service
the new tires.
Go to Step 16
4Are different types of tires used?
Go to Step 5
Replace the tires
with specified
ones, and service
the new tires.
Go to Step 16
51. Start the engine.
2. Shift the transfer lever to the high (TOD) position.
3. Fully turn the steering to the left (or right) end, and select the D
range and start the creep run.
Does the tight corner braking occur? Is the judder with chug-chug
sound observed? * Use caution on the operation.
Go to Step 6 Go to Step 11
61. Shift the transfer lever to the 2H position.
2. Fully turn the steering to the left (or right) end, and select the D
range and start the creep run.
Does the tight corner braking occur? Is the judder with chug-chug
sound observed? * Use caution on the operation.
Go to Step 7 Go to Step 14
7Is an LSD mounted to the rear differential? Go to Step 8 Go to Step 9
8Is the genuine LSD oil used in the rear differential?
Go to Step 9
Replace the
differential oil.
Go to Step 16
9Does the engine output the power correctly?
Go to Step 10
Check the
engine.
Go to Step 16
10Do the speed sensors work correctly? (Check trouble codes.)The ECU has
failed. Replace
the ECU.
Go to Step 16
Replace the
speed sensors.
Go to Step 16
11Is the tight corner braking observed only when the brake is
applied?
Go to Step 12
Conduct full
steering under
WOT.
Go to Step 5
121. Turn off the starter switch.
2. Disconnect the ECU connector.
Is the battery voltage observed between terminals (B±68)6 and
(B±67)11?
Go to Step 13
Repair the circuit
of terminal 6
(ABS IN).
Go to Step 16

5A±4
BRAKE CONTROL SYSTEM
normal braking when a malfunction has occurred in the
ABS.
The EHCU has a self-diagnosing function which can
indicate faulty circuits during diagnosis.
The EHCU is mounted on the engine compartment front
right side. It consists of a Motor, Plunger Pump, Solenoid
Valves and Check Valve.
On the outside, the relay box containing a motor relay and
a valve relay is installed.
Solenoid Valves: Reduces or holds the caliper fluid
pressure for each front disc brake or both rear disc brakes
according to the signal sent from the EHCU.
Reservoir: Temporarily holds the brake fluid that returns
from the front and rear disc brake caliper so that pressure
of front disc brake caliper can be reduced smoothly.
Plunger Pump: Feeds the brake fluid held in the reservoir
to the master cylinder.
Motor: Drives the pump according to the signal from
EHCU.
Check Valve: Controls the brake fluid flow.
ABS Warning Light
821RW033Vehicles equipped with the Anti-lock Brake System have
an amber ªABSº warning light in the instrument panel.
The ªABSº warning light will illuminate if a malfunction in
the Anti-lock Brake System is detected by the Electronic
Hydraulic Control Unit (EHCU). In case of an electronic
malfunction, the EHCU will turn ªONº the ªABSº warning
light and disable the Anti-lock braking function.
The ªABSº light will turn ªONº for approximately three
seconds after the ignition switch is to the ªONº position.
If the ªABSº light stays ªONº after the ignition switch is the
ªONº position, or comes ªONº and stays ªONº while
driving, the Anti-lock Brake System should be inspected
for a malfunction according to the diagnosis procedure.
Wheel Speed Sensor
It consists of a sensor and a rotor. The sensor is attached
to the knuckle on the front wheels and to the axle shaft
bearing holder on the rear wheels.
The rotor is press-fit in the axle shaft.The flux generated from electrodes magnetized by a
magnet in the sensor varies due to rotation of the rotor,
and the electromagnetic induction generates alternating
voltage in the coil. This voltage draws a ªsine curveº with
the frequency proportional to rotor speed and it allows
detection of wheel speed.
G-Sensor
The G-sensor installed inside the center console detects
the vehicle deceleration speed and sends a signal to the
EHCU. In 4WD operation, all four wheels may be
decelerated in almost the same phase, since all wheels
are connected mechanically.
This tendency is noticeable particularly on roads with low
friction coefficient, and the ABS control is adversely
affected.
The G-sensor judges whether the friction coefficient of
road surface is low or high, and changes the EHCU's
operating system to ensure ABS control.
Normal and Anti-lock Braking
Under normal driving conditions, the Anti-lock Brake
System functions the same as a standard power assisted
brake system. However, with the detection of wheel
lock-up, a slight bump or kick-back will be felt in the brake
pedal. This pedal ªbumpº will be followed by a series of
short pedal pulsations which occurs in rapid succession.
The brake pedal pulsation will continue until there is no
longer a need for the anti-lock function or until the vehicle
is stopped. A slight ticking or popping noise may be heard
during brake applications when the Anti-lock features is
being used.
When the Anti-lock feature is being used, the brake pedal
may rise even as the brakes are being applied. This is
also normal. Maintaining a constant force on the pedal
will provide the shortest stopping distance.
Brake Pedal Travel
Vehicles equipped with the Anti-lock Brake System may
be stopped by applying normal force to the brake pedal.
Although there is no need to push the pedal beyond the
point where it stops or holds the vehicle, by applying more
force the pedal will continue to travel toward the floor.
This extra brake pedal travel is normal.
Acronyms and Abbreviations
Several acronyms and abbreviations are commonly used
throughout this section:
ABS
Anti-lock Brake System
CKT
Circuit
DLC
Data Link Connector
EHCU
Electronic Hydraulic Control Unit
FL
Front Left

POWER ASSISTED BRAKE SYSTEM 5C – 5
TROUBLESHOOTING
Condition Possible Cause Correction
Brake Pull1. Tire inflation pressures unequal. 1. Adjust
2. Front wheel alignment incorrect. 2. Adjust
3. Unmatched tires on same axle. 3. Tire with approx. the same amount of
tread should be used on the same axle.
4. Restricted brake pipes or hoses. 4. Check for soft hoses and damaged
lines. Replace with new hoses and new
double-walled steel brake piping.
5. Water or oil on brake pads. 5. Clean or replace.
6. Brake pads hardened. 6. Replace.
7. Brake pads worn excessively. 7. Replace.
8. Brake rotor worn or scored. 8. Grind or replace.
9. Disc brake caliper malfunctioning. 9. Clean or replace.
10. Front hub bearing preload incorrect. 10. Adjust or replace.
11. Loose suspension parts. 11. Check all suspension mountings.
12. Loose calipers. 12. Check and tighten bolts to specifications.
Brake 1. Excessive lateral runout. 1. Check per instructions.
Roughness-orIf not within specifications, replace or
Chattermachine the rotor.
(Pulsates)2. Parallelism not within specifications. 2. Check per instructions.
If not within specifications, replace or
machine the rotor.
3. Wheel bearings not adjusted. 3. Adjust wheel bearings to correct
specifications.
4. Pad reversed (steel against iron). 4. Replace brake pad and machine rotor
to within specifications.
Excessive 1. Malfunctioning vacuum booster. 1. Check vacuum booster operation and
Pedal repair, if necessary.
Effort2. Partial system failure. 2. Check front and rear brake system for
failure and repair. Also, check brake
warning light. If a failed system is
found, the light should indicate a
failure.
3. Excessively worn pad. 3. Check and replace pads in sets.
4. Piston in caliper stuck or sluggish. 4. Remove caliper and rebuild.
5. Fading brakes due to incorrect pad. 5. Remove and replace with original
equipment pad or equivalent.
6. Vacuum leak to vacuum booster. 6. Check for ruptured or loose hose.
7. Check direction of check valve within 7. Correct vacuum hose direction.
vacuum hose.
8. Grease on the brake pads. 8. Replace or clean.
Excessive 1. Air in hydraulic circuit. 1. Bleed hydraulic circuit.
Brake Pedal 2. Level of brake fluid in resevoir too low. 2. Replenish brake fluid resevoir to
Travelspecified level and bleed hydraulic
circuit as necessary.
3. Master cylinder push rod clearance 3. Adjust.
excessive.
4. Leakage in hydraulic system. 4. Correct or replace defective parts.

POWER ASSISTED BRAKE SYSTEM 5C – 9
SERVICING
FILLING MASTER CYLINDER RESERVOIR
CAUTION:
1) Use only specified brake fluid. Do not use any
fluid which contains a petroleum base. Do not
use a container which has been used for
petroleum based fluids or a container which is
wet with water. Petroleum based fluids will
cause swelling and distortion of rubber parts in
the hydraulic brake system. Water mixed with
brake fluid lowers the fluid boiling point. Keep all
fluid containers capped to prevent
contamination.
2) Always fill the master cylinder reservoid when
the engine is cold.
3) Never allow the brake fluid to come in contact
with the painted surfaced.
The master cylinder reservoir must be kept properly
filled to ensure adequate reserve and to prevent air
and moisture from entering the hydraulic system.
However, because of expansion due to heat absorbed
from the brakes and the engine, the reservoir must not
be overfilled. The brake fluid reservoir is on the
master cylinder, which is located under the hood on
the driver side of the cowl. Thoroughly clean reservoir
cap before removal to avoid getting dirt into reservoir.
Remove cap and diaphragm. Add fluid as required to
bring level to the “MAX” mark on the reservoir tank.
Use “DOT 3“ Hydraulic Brake Fluid. If the fluid cap
diaphragm is stretched, return it to the original
position before installing.
DETERIORATION OF BRAKE FLUID
Using any other brake fluid than speficied or brake
fluid with mineral oil or water mixed in will drop the
boiling point of brake fluid. It may, in turn, reuslt in
vapor lock or deteriorated rubber parts of the
hydraulic system. Be sure to change brake fluid at
specified intervals.
If rubber parts are deteriorated, remover all the
system parts and clean them with alcohol. Prior to
reassembly, dry the cleaned parts with air to remove
the alcohol. Replace all hoses and rubber parts of the
system.
LEAKAGE OF BRAKE FLUID
With engine idling, set shift lever in the neutral
position and continue to depress brake pedal at a
constant pedal application force.
Should the pedal stroke become deeper gradually,
leak from the hydraulic pressure system is possible.
Make sure by visual check that there is no leak.