2002 ISUZU AXIOM brake light

5C±56
POWER±ASSISTED BRAKE SYSTEM
10. Install lower return spring (5).

Use brake spring tool.
11. Install auto adjuster lever (10).
12. Install upper (outer) return spring (6).

Use brake spring tool.
13. Install brake drum (2).

Adjust the brakes, refer to
Drum Brake Adjustment
in this section.
14. Install wheel and tire assembly (1).

Refer to
ªWheels and Tires º in wheel and Tire
System
section.
Drum Brake Adjustment (4y2 Model)
NOTE: All brakes are self-adjusting. Brakes are adjusted
by repeated stepping on the brake pedal. (After stepping
on the pedal and releasing it, the rear auto adjuster, in the
rear brake, produces a clicking sound.
The same operation should be repeated until the sound
disappears.)
Take the following steps after overhauling the rear brake
assembly.
1. Move the parking brake handle to its fully released
position.
2. Parking cable must be loosened sufficiently. (Loosen
the adjust nut and the lock nut.)
3. Repeat stepping on the brake pedal firmly, and
releasing it until the clicking sound can no longer be
heard.
If the difference between the brake drum inside
diameter and diameter of the brake shoes is adjusted
to be 0,5 mm, the number of times for depressing the
brake pedal can be reduced.
4. Remove the drum. Measure the brake drum inside
diameter and diameter of the brake shoes.
Shoe clearance: 0.25-0.4 mm (0.0098-0.0157 in)
If incorrect, check the brake auto-adjusting system.
5. Rotate the adjust nut until all slack disappears from
the cable. Set the adjust nut.
6. Applying about 30 kg (66 lb) of force, pull the parking
brake handle to its fully set position three or four
times.
7. If the parking brake is properly adjusted, the travel
between the fully disengaged position and the fully
engaged position will be between 9 and 11 notches.
If the traveling range is not within these limits, again
repeat steps 1 through 5.
After adjusting has been done, check to see if the rear
wheel rotates smoothly without drag when turned by
hand.
Servicing The Brake Drum
Whenever the brake drums are removed, they should be
thoroughly cleaned and inspected for cracks, scores,
deep grooves and out-of-round.
Cracked, Scored or Grooved Drum
A cracked drum is unsafe and must be replaced.
Do not attempt to weld a cracked drum.
Smooth any slight scores. Heavy or extensive scoring will
cause excessive brake lining wear, and it will probably be
necessary to machine the drum braking surface.
If the brake linings are slightly worn and the drum is
grooved, the drum should be polished with fine emery
cloth but should not be machined. At this stage,
eliminating all the grooves in the drum and smoothing the
ridges on the lining would require the removal of too much
metal and lining. If left alone, the grooves and ridges
match and satisfactory service can be obtained. If brake
linings are to be replaced, a grooved drum should be
machined. Using a grooved drum with new linings will
create inefficient braking performance and cause the
linings to wear quicker.
Out-Of-Round Drum
An out-of-round drum makes accurate brake shoe
adjustment impossible and is likely to cause excessive
wear to other parts of the brake mechanism due to its
eccentric action. An out-of-round drum can also cause
severe and irregular tire tread wear as well as a pulsing
brake pedal. When the braking surface of a brake drum
exceeds the specification limit of 0.15 mm (0.006 in) in
out-of-round, the drum should be machined to true up the
braking surface. Out-of-round can be accurately
measured with an inside micrometer fitted with proper
extension rods. When measuring a drum for out-of-round
and wear, take measurements at the open and closed
edges of machines surfaces and at right angles to each
other.
Maximum out-of-round: 0.15 mm (0.006 in)
420RS034

5C±61 POWER±ASSISTED BRAKE SYSTEM
AXIOM (Vehicles Produced After Aug./1/2001)
POWER-ASSISTED BRAKE SYSTEM
CONTENTS
Service Precaution 5C±62. . . . . . . . . . . . . . . . . . . . . .
General Description 5C±62. . . . . . . . . . . . . . . . . . . . .
Diagnosis 5C±66. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
General Diagnosis 5C±67. . . . . . . . . . . . . . . . . . . . . . .
Hydraulic Brakes 5C±70. . . . . . . . . . . . . . . . . . . . . . . .
Filling Master Cylinder Reservoir 5C±70. . . . . . . .
Deterioration of Brake Fluid 5C±70. . . . . . . . . . . . .
Leakage of Brake Fluid 5C±70. . . . . . . . . . . . . . . . .
Bleeding Brake Hydraulic System 5C±70. . . . . . . .
Flushing Brake Hydraulic System 5C±71. . . . . . . .
Brake Pipes and Hoses 5C±71. . . . . . . . . . . . . . . .
Brake Hose Inspection 5C±71. . . . . . . . . . . . . . . . .
Front Caliper Brake Hose 5C±72. . . . . . . . . . . . . . . .
Front Caliper Brake Hose and Associated
Parts 5C±72. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Removal 5C±72. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation 5C±72. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Rear Axle Brake Hose 5C±73. . . . . . . . . . . . . . . . . . .
Rear Axle Brake Hose and Associated
Parts 5C±73. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Removal 5C±73. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation 5C±73. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Brake Pipe 5C±74. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Removal 5C±74. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation 5C±74. . . . . . . . . . . . . . . . . . . . . . . . . . . .
P & B (Proportioning and Bypass) Valve 5C±75. . . .
Removal 5C±75. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation 5C±75. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Main Data and Specifications 5C±76. . . . . . . . . . . . .
Brake Pedal 5C±77. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Checking Pedal Height 5C±77. . . . . . . . . . . . . . . . .
Checking Pedal Travel 5C±77. . . . . . . . . . . . . . . . .
Brake Pedal and Associated Parts 5C±78. . . . . . .
Removal 5C±78. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation 5C±78. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Stoplight Switch 5C±79. . . . . . . . . . . . . . . . . . . . . . . . .
Parts Location 5C±79. . . . . . . . . . . . . . . . . . . . . . . .
Removal 5C±79. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation 5C±79. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Main Data and Specifications 5C±80. . . . . . . . . . . . .
Master Cylinder Assembly 5C±81. . . . . . . . . . . . . . . .
Master Cylinder Assembly and Associated
Parts 5C±81. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Removal 5C±81. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Inspection 5C±81. . . . . . . . . . . . . . . . . . . . . . . . . . . . Master Cylinder Assembly 5C±82. . . . . . . . . . . . . . . .
Master Cylinder Assembly Desassembled
View 5C±82. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Desassembly 5C±82. . . . . . . . . . . . . . . . . . . . . . . . .
Inspection 5C±82. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Reassembly 5C±83. . . . . . . . . . . . . . . . . . . . . . . . . .
Installation 5C±83. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Main Data and Specifications 5C±84. . . . . . . . . . .
Vacuum Booster Assembly 5C±85. . . . . . . . . . . . . . .
Vacuum Booster Assembly and Associated
Parts 5C±85. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Removal 5C±85. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Inspection and Repair 5C±86. . . . . . . . . . . . . . . . . .
Exterior Components 5C±87. . . . . . . . . . . . . . . . . . . .
Exterior Components and Associated
Parts 5C±87. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Removal 5C±87. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Inspection and Repair 5C±88. . . . . . . . . . . . . . . . . .
Installation 5C±88. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Vacuum Booster Overhaul 5C±88. . . . . . . . . . . . . . . .
Vacuum Booster 5C±88. . . . . . . . . . . . . . . . . . . . . . .
Main Data and Specifications 5C±89. . . . . . . . . . . . .
Front Disc Brake Pads 5C±90. . . . . . . . . . . . . . . . . . .
Front Disc Brake Pads Inspection 5C±90. . . . . . . .
Front Disc Brake Pads and Associated
Parts 5C±90. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Removal 5C±91. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation 5C±91. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Front Disc Brake Rotor 5C±93. . . . . . . . . . . . . . . . . . .
Inspection 5C±93. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Replacing Brake Rotors 5C±93. . . . . . . . . . . . . . . .
Refinishing Brake Rotors 5C±93. . . . . . . . . . . . . . .
Front Disc Brake Caliper Assembly 5C±95. . . . . . . .
Front Disc Brake Caliper Assembly and
Associated Parts 5C±95. . . . . . . . . . . . . . . . . . . . . .
Removal 5C±95. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation 5C±96. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Front Disc Brake Caliper 5C±98. . . . . . . . . . . . . . . . .
Front Disc Brake Caliper Disassembled
View 5C±98. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Disassembly 5C±98. . . . . . . . . . . . . . . . . . . . . . . . . .
Inspection and Repair 5C±99. . . . . . . . . . . . . . . . . .
Reassembly 5C±99. . . . . . . . . . . . . . . . . . . . . . . . . .
Main Data and Specifications 5C±100. . . . . . . . . . .
Rear Disc Brake Pads (4y4 Model) 5C±101. . . . . . . .

5C±66
POWER±ASSISTED BRAKE SYSTEM
Diagnosis
Road Testing The Brakes
Brake Test
Brakes should be tested on a dry, clean, reasonably
smooth and level roadway. A true test of brake
performance cannot be made if the roadway is wet,
greasy or covered with loose dirt where all tires do not grip
the road equally. Testing will also be adversely affected if
the roadway is crowned so as to throw the weight of the
vehicle toward wheels on one side or if the roadway is so
rough that wheels tend to bounce. Test the brakes at
different vehicle speeds with both light and heavy pedal
pressure; however, avoid locking the wheels and sliding
the tires. Braking without locking the tires will stop the
vehicle in less distance than braking to a skid (which has
no brake efficiency). More tire to road friction is present
while braking without locking the tires than braking to a
skid.
The standard brake system is designed and balanced to
avoid locking the wheels except at very high deceleration
levels.
It is designed this way because the shortest stopping
distance and best control is achieved without brake
lock±up.
Because of high deceleration capability, a firmer pedal
may be felt at higher deceleration levels.
External Conditions That Affect Brake Performance
1. Tires: Tires having unequal contact and grip on the
road will cause unequal braking. Tires must be
equally inflated, identical in size, and the thread
pattern of right and left tires must be approximately
equal.
2. Vehicle Loading: A heavily loaded vehicle requires
more braking effort.
3. Wheel Alignment: Misalignment of the wheels,
particularly in regard to excessive camber and caster,
will cause the brakes to pull to one side.
Brake Fluid Leaks
With engine running at idle and the transmission in
ªNeutralº, depress the brake pedal and hold a constant
foot pressure on the pedal. If pedal gradually falls away
with the constant pressure, the hydraulic system may be
leaking.
Check the master cylinder fluid level. While a slight drop in
the reservoir level will result from normal lining wear, an
abnormally low level in reservoir indicates a leak in the
system. The hydraulic system may be leaking internally
as well as externally. Refer to
Master Cylinder Inspection.
Also, the system may appear to pass this test but still
have slight leakage. If fluid level is normal, check the
vacuum booster push rod length. If an incorrect length
push rod is found, adjust or replace the push rod. Check
the brake pedal travel and the parking brake adjustment.
When checking the fluid level, the master cylinder fluid
level may be lower than the ªMAXº mark if the front and
rear linings are worn. This is normal.
Warning Light Operation
When the ignition switch is in the START position, the
ªBRAKEº warning light should turn on and go off when the
ignition switch returns to the ON position.
The following conditions will activate the ªBRAKEº light:
1. Parking brake applied. The light should be on
whenever the parking brake is applied and the ignition
switch is on.
2. Low fluid level. A low fluid level in the master cylinder
will turn the ªBRAKEº light on.
3. During engine cranking the ªBRAKEº light should
remain on. This notifies the driver that the warning
circuit is operating properly.

5C±67 POWER±ASSISTED BRAKE SYSTEM
General Diagnosis
ConditionPossible causeCorrection
Brake PullTire inflation pressure is unequal.Adjust
Front wheel alignment is incorrect.Adjust
Unmatched tires on same axle.Tires with approx. the same amount
of tread should be used on the same
axle.
Restricted brake pipes or hoses.Check for soft hoses and damaged
lines. Replace with new hoses and
new double walled steel brake
piping.
Water or oil on the brake pads.Clean or replace.
Brake pads hardened.Replace
Brake pads worn excessively.Replace
Brake rotor worn or scored.Grind or replace.
Disc brake caliper malfunctioning.Clean or replace.
Front hub bearing preload incorrect.Adjust or replace.
Loose suspension parts.Check all suspension mountings.
Loose calipers.Check and tighten the bolts to
specifications.
Brake Roughness or Chatter
(Pulsates)Excessive lateral runout.Check per instructions. If not within
specifications, replace or machine
the rotor.
Parallelism not within specifications.Check per instructions. If not within
specifications, replace or machine
the rotor.
Pad reversed (steel against iron).Replace the brake pad and machine
rotor to within specifications.
Excessive Pedal EffortMalfunctioning vacuum booster.Check the vacuum booster operation
and repair, if necessary.
Partial system failure.Check the front and rear brake
system for failure and repair. Also,
check the brake warning light. If a
failed system is found, the light
should indicate failure.
Excessively worn pad.Check and replace pads in sets.
Piston in caliper stuck or sluggish.Remove caliper and rebuild.
Fading brakes due to incorrect pad.Remove and replace with original
equipment pad or equivalent.
Vacuum leak to vacuum booster.Check for ruptured or loose hose.
Check the direction of check valve
within vacuum hose.Correct vacuum hose direction.
Grease on the brake pads.Replace or clean.
Excessive Brake Pedal TravelAir in hydraulic circuit.Bleed the hydraulic circuit.
Level of brake fluid in the reservoir
too low.Replenish brake fluid reservoir to
specified level and bleed hydraulic
circuit as necessary.
Master cylinder push rod clearance
excessive.Adjust
Leakage in hydraulic system.Correct or replace defective parts.

5C±68
POWER±ASSISTED BRAKE SYSTEM
Condition CorrectionPossible cause
Brake DragMaster cylinder pistons not returning
correctly.Adjust the stop light switch and
vacuum booster push rod. If
necessary, rebuild.
Restricted brake pipes or hoses.Check for soft hoses or damaged
pipes, and replace with new hoses
and new double±walled steel brake
piping.
Parking brake maladjusted.Adjust
Parking brake lining clearance
insufficient.Adjust
Brake pedal free play insufficient.Adjust the brake pedal height or
power cylinder operating rod.
Piston in the master cylinder sticking.Replace
Piston in the disc brake caliper
sticking.Replace piston seals.
Brake pads sticking in caliper.Clean
Return spring weakened.Replace
Parking brake binding.Overhaul the parking brakes and
correct.
Front hub bearing preload incorrect.Adjust or replace.
Parking brake shoes not returning.Correct or replace the brake back
plate and brake shoe as necessary.
Obstructions in hydraulic circuit.Clean
Rotor warped excessively.Grind or replace.
Rear brake drum distorted.Grind or replace.
Parking cable sticking.Grind or replace.
Grabbing or Uneven Braking Action
(All conditions listed under ªPullsº)Malfunctioning vacuum booster.Check operation and correct as
necessary.
Binding brake pedal mechanism.Check and lubricate, if necessary.
Corroded caliper assembly.Clean and lubricate.
Brake NoisyBrake pads are worn.Replace
Brake pads are hardened.Replace
Brake pads are in poor contact with
rotor.Correct
Brake disc(s) warped, worn or
damaged.Grind or replace.
Disc brake anti±squeak shims
fatigued.Replace
Front hub bearings are loose or
preload is incorrect.Adjust or replace.
Brake disc is rusted.Grind or replace.

5C±71 POWER±ASSISTED BRAKE SYSTEM
NOTE: Do not allow the fluid level in the reservoir to go
below the half±way mark.
12. Reconnect the brake pipe (1) to the master cylinder
and tighten the pipe.
13. Depress the brake pedal slowly once and hold it
depressed.
14. Loosen the rear wheel brake pipe (1) at the master
cylinder.
15. Retighten the brake pipe, then release the brake
pedal slowly.
16. Repeat steps 13 through 15 until no air comes out of
the port when the brake pipe is loosened
NOTE: Be very careful not to allow the brake fluid to come
in contact with painted surfaces.
330R200004
17. Bleed the air from the front wheel brake pipe
connection (2) by repeating steps 7 through 16.
Bleeding the Caliper
18. Bleed the air from each wheel in the order listed
below:

Right rear caliper or wheel cylinder

Left rear caliper or wheel cylinder

Right front caliper

Left front caliper
Conduct air bleeding from the wheels in the above
order. If no brake fluid comes out, it suggests that air
is mixed in the master cylinder. In this case, bleed air
from the master cylinder in accordance with steps 7
through 17, and then bleed air from the caliper or
wheel cylinder.
19. Place the proper size box end wrench over the
bleeder screw.
20. Cover the bleeder screw with a transparent tube, and
submerge the free end of the transparent tube in a
transparent container containing brake fluid.
21. Pump the brake pedal slowly three (3) times
(once/sec), then hold it depressed.
22. Loosen the bleeder screw until fluid flows through the
tube.
23. Retighten the bleeder screw.24. Release the brake pedal slowly.
25. Repeat steps 21 through 24 until the air is completely
removed.
It may be necessary to repeat the bleeding procedure
10 or more times for front wheels and 15 or more
times for rear wheels.
26. Go to the next wheel in the sequence after each wheel
is bled.
Be sure to monitor reservoir fluid level.
27. Depress the brake pedal to check if you feel
ªsponginessº after the air has been removed from all
wheel cylinders and calipers.
If the pedal feels ªspongyº, the entire bleeding
procedure must be repeated.
28. After the bleeding operation is completed on the each
individual wheel, check the level of the brake fluid in
the reservoir and replenish up to the ªMAXº level as
necessary.
29. Attach the reservoir cap.
If the diaphragm inside the cap is deformed, reform
it and install.
30. Stop the engine.
Flushing Brake Hydraulic System
It is recommended that the entire hydraulic system be
thoroughly flushed with clean brake fluid whenever new
parts are installed in the hydraulic system. Approximately
one quart of fluid is required to flush the hydraulic system.
The system must be flushed if there is any doubt as to the
grade of fluid in the system or if fluid has been used which
contains the slightest trace of mineral oil. All rubber parts
that have been subjected to a contaminated fluid must be
replaced.
Brake Pipes and Hoses
The hydraulic brake system components are
interconnected by special steel piping and flexible hoses.
Flexible hoses are used between the frame and the front
calipers, the frame and rear axle case and the rear axle
and the rear calipers.
When the hydraulic pipes have been disconnected for
any reason, the brake system must be bled after
reconnecting the pipe. Refer to
Bleeding the Brake
Hydraulic System
in this section.
Brake Hose Inspection
The brake hose should be inspected at least twice a year.
The brake hose assembly should be checked for road
hazard, cracks and chafing of the outer cover, and for
leaks and blisters. Inspect for proper routing and
mounting of the hose. A brake hose that rubs on
suspension components will wear and eventually fail. A
light and mirror may be needed for an adequate
inspection. If any of the above conditions are observed on
the brake hose, adjust or replace the hose as necessary.
CAUTION: Never allow brake components such as
calipers to hang from the brake hoses, as damage to
the hoses may occur.

5C±75 POWER±ASSISTED BRAKE SYSTEM
P & B (Proportioning and Bypass) Valve
P & B (Proportioning and Bypass)
Valve Sectional View
350RW014
Legend
(1) Master Cylinder (Secondary)
(2) Master Cylinder (Primary)
(3) Rear Brake
(4) Front Brake
The P&B valve contains two sections, each serving a
different function.
The proportioning section of the P&B valve proportions
outlet pressure to the rear brakes after a predetermined
rear input pressure has been reached. This is done to
prevent rear wheel lock up on the vehicles with light rear
wheel loads. The valve has a by±pass feature which
assures full system pressure to the rear brakes in the
event of front brake system malfunction. Also full front
pressure is retained in the event of rear brake
malfunction.
The P&B valve is not repairable and must be replaced as
complete assembly.
Removal
1. The P&B valve is not repairable and must be replaced
as a complete assembly. Care must be taken to
prevent brake fluid from contacting any painted
surface.
2. Remove hydraulic pipes (1) and plug the pipes (1) to
prevent the loss of fluid or the entrance of dirt.
3. Remove bolt (3).
4. Remove P&B valve (2).
350R200003
Installation
1. Install P&B valve (2).
2. Install bolt (3) and tighten the bolt to the specified
torque.
Torque: 22 N´m (16 lb ft)
3. Install hydraulic pipes (1) and tighten the bolt to the
specified torque.
Torque: 12 N´m (104 lb in)
4. After installing the brake pipes, bleed the brakes as
described in
Bleeding Brake Hydraulic System in this
section.

5C±77 POWER±ASSISTED BRAKE SYSTEM
Brake Pedal
Checking Pedal Height
The push rod serves as the brake pedal stopper when the
pedal is fully released. Brake pedal height adjustment
should be performed as follows:
Adjust Brake Pedal
310R200002
1. Measure the brake pedal height after making sure the
pedal is fully returned by the pedal return spring.
Pedal height must be measured after starting the
engine and stepping on it several times.
Pedal Free Play: 6-10 mm (0.23-0.39 in)
Pedal Height: 173-185 mm (6.81-7.28 in)
NOTE: Pedal free play must be measured after turning
off the engine and stepping on the brake pedal firmly five
times or more.
2. If the measured value is not within the above range,
adjust the brake pedal as follows:
a. Disconnect the stoplight switch connector.
b. Loosen the stoplight switch lock nut.
c. Rotate the stoplight switch so that it moves away
from the brake pedal.
d. Loosen the lock nut (1) on the push rod.
e. Adjust the brake pedal to the specified height by
rotating the push rod in the appropriate direction.
f. Tighten the lock nut to the specified torque.
Torque: 20 N´m (15 lb ft)
g. Adjust the stoplight switch (2) to the specified
clearance (between the switch housing and the
brake pedal) by rotating the switch housing.
Clearance: 0.5±1.0 mm (0.02±0.04 in)
310RY00005
NOTE: While adjusting the stoplight switch, make sure
that the threaded part of the stoplight switch does not
push the brake pedal.
h. Tighten the stoplight switch lock nut.
i. Connect the stoplight switch connector.
Checking Pedal Travel
310R200002
1. Pedal height must be measured after starting the
engine and revving it several times to apply vacuum
to the vacuum booster fully.
NOTE: Pedal height must be 95 mm (3.7 in) or more
when about 50 kg (110.25 lb) of stepping force is applied.
2. If the measured value is lower than the above range,
air may still be present in the hydraulic system
Perform the bleeding procedure.