2002 ISUZU AXIOM air bleeding

5C±15 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).
350RW026
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: 15 N´m (11 lb ft)
4. After installing the brake pipes, bleed the brakes as
refer to
Bleeding Brake Hydraulic System in this
section.

5C±17 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
310RY00004
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 receiving it several times.
Pedal Free Play: 6-10 mm (0.23-0.39 in)
Pedal Free Play: 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
310RY00004
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.

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±63 POWER±ASSISTED BRAKE SYSTEM
The master cylinder contains two pistons that supply the
hydraulic pressure for a dual±circuit braking system. The
primary piston provides the fluid pressure to the front
brakes, while the secondary piston provides the fluid
pressure to the rear brakes. If the pressure is lost from
either system, the remaining system will function to stop
the vehicle.CAUTION:
1. If any hydraulic component is removed or
disconnected, it may be necessary to bleed all or
part of the brake system. (Refer to
Bleeding Brake
Hydraulic System
in this section.)
2. The torque values specified are for dry,
unlubricated fasteners.
3. Perform service operations on a clean bench free
from all mineral oil materials.
Brake Booster
331R200001
This booster is a tandem vacuum unit with a diaphragm
effective diameter 205mm + 230mm (8.07in + 9.06in). In
normal operating mode, with the service brakes in the
released position, the tandem vacuum booster operates
with vacuum on both sides of its diaphragms. When the
brakes are applied, air at atmospheric pressure is
admitted to both sides of the diaphragm to provide the
power assist. When the service brake is released, the
atmospheric air is shut off from both sides of the
diaphram. The air is then drawn from the booster through
the vacuum check valve to the vacuum source.CAUTION:
1. If any hydraulic component is removed or
disconnected, it may be necessary to bleed all or
part of the brake system.
2. The torque values specified are for dry,
unlubricated fasteners.
3. The vacuum booster is not repairable and must be
replaced as complete assembly.

5C±70
POWER±ASSISTED BRAKE SYSTEM
Hydraulic Brakes
Filling Master Cylinder Reservoir
CAUTION: 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 fluid 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.
Always fill the master cylinder reservoir when the en-
gine is cold.
Never allow the brake fluid to come in contact with
the painted surfaces.
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 ab-
sorbed 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 left side of the cowl. Thoroughly clean reser-
voir cap before removal to avoid getting dirt into res-
ervoir. Remove the diaphragm. Add fluid as required
to bring level to the ªMAXº mark on the reservoir
tank. Use ªDOT 3º 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 specified or brake fluid
with mineral oil or water mixed in will drop the boiling point
of brake fluid. It may, in turn, result in vapor lock or
deteriorated rubber parts of the hydraulic system. Be sure
to change the brake fluid at specified intervals.
If the rubber parts are deteriorated, remove all the system
parts and clean them with alcohol. Prior to reassembly,
dry the cleaned parts with air to remove the alcohol.
Replace all the 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,
leakage from the hydraulic pressure system is possible.
Perform visual inspection for any signs of leakage.
Bleeding Brake Hydraulic System
A bleeding operation is necessary to remove air from the
hydraulic brake system whenever air is introduced into
the hydraulic system. It may be necessary to bleed the
hydraulic system at all four brakes if air has been
introduced through a low fluid level or by disconnecting
brake pipes at the master cylinder. If a brake pipe is
disconnected at one wheel, only that wheel
cylinder/caliper needs to be bled. If the pipes are
disconnected at any fitting located between the master
cylinder and brakes, then the brake system served by the
disconnected pipe must be bled.
1. For 4±Wheel Antilock Brake System (ABS) equipped
vehicle, be sure to remove the ABS main fuse 60A
located at the relay and fuse box before bleeding air. If
you attempt to bleed air without removing the main
fuse, air cannot be let out thoroughly, and this may
cause damage to the hydraulic unit. After bleeding air,
be sure to replace the ABS main fuse back to its
original position.
2. Set the parking brake completely, then start the
engine.
NOTE: The vacuum booster will be damaged if the
bleeding operation is performed with the engine off.
3. Remove the master cylinder reservoir cap.
4. Fill the master cylinder reservoir with brake fluid.
Keep the reservoir at least half full during the air
bleeding operation
5. Always use new brake fluid for replenishment.
6. When replenishing the brake fluid reservoir, carefully
pour in the brake fluid to prevent air bubbles from
entering the brake system.
When the master cylinder is replaced or overhauled,
first bleed the air from the master cylinder, then from
each wheel cylinder and caliper following the
procedures described below.
Bleeding the Master Cylinder
7. Disconnect the rear wheel brake pipe (1) from the
master cylinder.
Check the fluid level and replenish as necessary. If
replenished, leave the system for at least one minute.
8. Depress the brake pedal slowly once and hold it
depressed.
9. Completely seal the delivery port of the master
cylinder with your finger, where the pipe was
disconnected then release the brake pedal slowly.
10. Release your finger from the delivery port when the
brake pedal returns completely.
11. Repeat steps 8 through 10 until the brake fluid comes
out of the delivery port during step 8.

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.