service ISUZU TROOPER 1995 Repair Manual

SA 16 HYDRAULIC BRAKES
MASTER CYLINDER ASSEMBLY
GENERAL DESCRIPTION
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. l.f ~he
pressure is lost from either system, the rema1n1ng
system will function to stop the vehicle.
\fl CAUTION:
VI • The master cylinder is not repairable. If found
defective,
it must be replaced as complete
assembly.
• If any hydraulic component is removed or
disconnected, it may be necessary to bleed all
or part of the brake system. (Refer to "On­
Vehicle Service" previously in this section.)
• The torque values specified are for dry,
unlubricated fasteners.
• Perform service operations on a clean bench
free
from all mineral oil materials.
Fig.
5A-15
•

HYDRAULIC BRAKES 5A-17
ON-VEHICLE SERVICE
FLUID RESERVOIR TANK
2
T 4
3 1
Removal steps
1. Electrical connector 2. Retainer
3. Fluid reservoir
4. 0-ring
Installation steps
To install, follow the removal steps in the reverse order.
Fig. 5A-16
1••1 REMOVAL
NOTE:
Before removing fluid reservoir, remove brake fluid
from fluid reservoir.
1. Electrical connector
2. Retainer (Fig. 5A-17)
Fig. 5A-17
3. Fluid reservoir
• The fluid level sensor is built into the fluid
reservoir (Except rear wheel anti lock model). It
cannot be removed for servicing.
4. 0-ring
1••1 INSTALLATION
To install, follow the removal steps in the reverse
order, noting the
following points;
4. 0-ring (Fig. 5A-18)
• 0-ring must be set onto the fluid reservoir,
before
installing fluid reservoir.
Fluid reservoir
0-ring
Fig. 5A-18

BRAKE BOOSTER SYSTEM 5A 1-1
SECTION 5A1
BRAKE BOOSTER SYSTEM
W CAUTION:
• Fasteners are an important attaching part in that they could affect performance of vital parts and systems,
and/or could result in major repair expense. They must be replaced with one of the same part number or with
an equivalent part if replacement becomes necessary. Do not use replacement parts of lesser quality or
substitute design. Torque values must be used as specified during reassembly to assure proper retention of
these parts.
CONTENTS
General Description . . . . . . . . . . . . . . . . . . . SA 1-1 Vacuum Booster .................... SA1-6
Diagnosis ..................... See Section SA Main Data and Specifications ........... SA1-6
On-Vehicle Service ................... SA1-2 General Specifications ............... SA1-6
Vacuum Booster Assembly ........... SA1-2 Torque Specifications ................ SA1-6
Exterior Components ................ SA1-4 Special Tools ......................... SA1-7
Unit Repair .......................... SA1-6
GENERAL DESCRIPTION
This booster is a tandem vacuum unit with a
diaphragm effective diameter
205 mm + 230 mm. 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 one side of each diaphragm to
provide the power assist. When the service brake is
released, the atmospheric air is shut off from the one
side
of each diaphragm. The air is then drawn from the
booster through the vacuum check
valve to the
vacuum source.
W CAUTION:
• If any hydraulic component IS removed or
disconnected, it may be necessary to bleed all
or part of the brake system.
Fig.
5A1-1
• The torque values specified are for dry,
unlubricated fasteners.
• The vacuum booster is not repairable and must
be replaced as complete assembly.

SA 1-2 BRAKE BOOSTER SYSTEM
ON-VEHICLE SERVICE
VACUUM BOOSTER ASSEMBLY
4
7
'
I ,
l_
Removal Steps 1. Master cylinder
2. Vacuum hose
3. Yoke clevis 4. Vacuum booster fixing nut 5. Vacuum booster
Installation steps
To install, follow the removal steps in the reverse order
®I
®'
Fig. 5A1-2
1••1 REMOVAL
• Before removing the vacuum booster
assembly, disconnect and remove brake pipes.
1. Master cylinder
• Refer to "Master Cylinder Removal" in Section
5A.
'\fCAUTION:
When removing master cylinder from vacuum
booster, be sure to get rid
of the internal negative
pressure
of the vaccum booster (by, for instance,
disconnecting vaccum hose) in advance.
If any negative pressure remains in the vaccum
booster, the piston may
possibly come out when
the master cylinder is being removed, letting the
brake
fluid run out.
While removing master cylinder, further, do not
hold the piston as it can be easily pulled out.
Outside surface of the piston is the surface on
which
seals are to slide. Care should be taken to
keep the surface free of cuts and dents.
2. Vacuum hose
3. Yoke clevis
• Disconnect the yoke clevis from the brake
pedal.
4. Vacuum booster fixing nut
5. Vacuum booster
Fig. 5A1-3
~ INSPECTION AND REPAIR
Vacuum hose (Fig. 5A1-3)
Inspect the check valve, which is installed inside
the vacuum hose.
• Air should pass freely from the vacuum booster
to the engine.
• Air should not pass from the engine to the
vacuum booster.
If it does, the check valve is
inoperative and
must be replaced.
•

DISC BRAKES 5A2-1
SECTION 5A2
DISC BRAKES
w CAUTION:
All brake attaching fasteners are an important attaching part in that they could affect performance of vital
parts and systems, and/or could result in major repair expense. They must be replaced with one of the same
part
number or with an equivalent part if replacement becomes necessary. Do not use replacement parts of
lesser quality or substitute design. Torque values must be used as specified during reassembly to assure
proper retention of these parts.
CONTENTS
General Description . . . . . . . . . . . . . . . . . . . . 5A2-1
Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5A2-1
Diagnosis
..................... See Section SA
On-Vehicle Service . . . . . . . . . . . . . . . . . . . . 5A2-2
Front Disc Brakes . . . . . . . . . . . . . . . . . . . . 5A2-2
Brake Pads
Inspection . .

. . . . . . . . . . . . 5A2-2
Brake Pads Replacement . . . . . . . . . . . 5A2-3
Servicing
the Rotor . . . . . . . . . . . . . . . . 5A2-4
Caliper Replacement . .

. . . . . . . . . . . . . 5A2-6
Rebuilding
the Caliper . . . . . . . . . . . . . 5A2-8 Rear
Disc Brakes .................... 5A2-1 0
Brake
Pads Inspection ............. 5A2-1 0
Brake Pads Replacement ........... 5A2-1 0
Servicing the Rotor ............... 5A2-12
Caliper Replacement .............. 5A2-14
Rebuilding the
Caliper ............. 5A2-17
Parking Brakes . . . . . . . . . . . . . . . .
See Section SC
Main Data and Specifications ........... 5A2-19
General Specifications ............... 5A2-19
Torque Specifications
............... 5A2-19
GENERAL DESCRIPTION
The disc brake assembly consists of a caliper, piston,
rotor, pad assembly and
support bracket. The caliper
assembly has a single bore and is mounted to the
support bracket with 2 mounting bolts. The support
bracket allows the caliper to move laterally against the
rotor. The
caliper is a one-piece casting with the
inboard side containing the piston bore. A square cut
rubber
seal is located in a groove in the piston bore
which provides the hydraulic seal between the piston
and the cylinder
wall.
NOTE:
• Replace all components included in repair kits
used
to service this caliper.
• Lubricate rubber parts with clean brake fluid to
ease assembly.
• If any hydraulic component is removed or
disconnected, it may be necessary to bleed all or
part of the brake system.
• Replace pads in axle sets only.
•
The torque values specified are for dry,
unlubricated fasteners.
• Perform service operation a clean bench free
from all mineral oil materials.
OPERATION
Hydraulic pressure, created by applying the brake
pedal, is converted by the caliper to a stopping force.
This force acts
equally against the piston and the
bottom of the caliper bore to move the piston outward
and to move (slide) the caliper inward resulting in a
clamping action on the rotor. This clamping action
forces the
linings against the rotor, creating friction to
stop the vehicle.

5A2-2 DISC BRAKES
Front disc brakes
/
Rear disc brakes
I
I
Fig. 5A2-1
ON-VEHICLE SERVICE
FRONT DISC BRAKE
BRAKE PADS INSPECTION (Fig. 5A2-2)
Check the outer pad by looking at each caliper from
above. Check the thickness on the inner pad by looking
down through the inspection hole in the top of the
caliper. Whenever the pad is worn to about the
thickness
of the pad base, the pad should be removed
for further measurements. The pad should be replaced
anytime the pad thickness (t) is worn to within 1.0 mm
(0.039 in) of the pad itself.
The disc pads have a wear indicator that makes a noise
when the pad wears
to where replacement is required.
~~~ Minimum limit mm (in) j 1.0 (0.039)
Fig. 5A2-2
I I

•

REAR WHEEL ANTILOCK BRAKE SYSTEM 5A3-1
SECTION 5A3
REAR WHEEL ANTILOCK BRAKE SYSTEM
(RWAL}
w CAUTION:
• All brake attaching fasteners are an important attaching part in that they could affect performance of vital
parts and systems, and/or could result in major repair expense. They must be replaced with one of the same
part
number or with an equivalent part if replacement becomes necessary. Do not use replacement parts of
lesser quality or substitute design. Torque values must be used as specified during reassembly to assure
proper retention of these parts.
CONTENTS
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 5A3· 1
General Description . .
. . . . . . . . . . . . . . .
5A3· 1
Rear
Wheel Antilock (RWAL) Control
Parts Location . .

. . . . . . . . . . . . . . . . .
5A3· 5
System Diagram . .

. . . . . . . . . . . . . . . . . . . .
5A3· 6
Rear
Wheel Antilock (RWAL) System
Diagnostics . .

. . . . . . . . . . . . . . . . . . . . . .
5A3· 7
On-Vehicle Service . .

. . . . . . . . . . . . . . . . .
5A3·38
RWAL Electronic Brake Control
Module (EBCM) Replacement ....... 5A3-38
Antilock
(Isolation/Dump) Valve
Replacement ..................... 5A3-39
Speed Sensor Replacement
.......... 5A3-40
Main Data and Specifications ........... 5A3-41
Torque Specifications
............... 5A3-41
INTRODUCTION
This section deals with the complete diagnosis and
services
for vehicles equipped with rear wheel
antilock.
For service information regarding all other
components
of the brake system, refer to "Hydraulic
Brakes"
(Sec. SA), "Brake Booster System" (Sec. SA 1)
or "Disc Brakes" (Sec. SA2) of this Manual.
GENERAL DESCRIPTION
The rear wheel anti lock system (RWAL) is designed to
reduce rear wheel lock-up during a severe brake
application,
thus maintaining rear end stability. The
system functions
by regulating the rear hydraulic
brake line pressure. The pressure regulation is
accomplished
by an anti lock valve which is located on
the
front right side of engine room. The anti lock valve
is made up of two valves, a dump valve which releases
pressure into an accumulator and an isolation valve
which maintains rear brake pressure. The valve is
controlled
by a microcomputer which is part of the
Electronic Brake Control Module (EBCM). The
EBCM is mounted at the
front of the center
console. Under severe brake application, as pressure
is
applied to the brake pedal, the EBCM is designed to
permit the valve to do one of three functions or a
combination
of all three. The EBCM will allow the valve
to either maintain the same amount of hydraulic
pressure, release hydraulic pressure through the
dump valve into the accumulator or increase the
pressure by
pulsing the isolation valve.
The EBCM operates by receiving signals from the
speed sensor (which
is located in the differential
carrier), combination
valve and the brake light switch.
The RWAL system is connected
to the RWAL indicator
light located on the dash. An indication of the RWAL
operation and a
bulb check is performed each time the
ignition is turned
"ON". The indicator light will remain
on
for about two seconds. A RWAL system
malfunction is indicated if the RWAL indicator light
stays on, or comes on during driving. To determine the
specific
trouble, refer to "RWAL System Diagnostics"
in this section.

REAR WHEEL ANTILOCK BRAKE SYSTEM 5A3-7
REAR WHEEL ANTILOCK (RWAL) SYSTEM DIAGNOSTICS
DIAGNOSIS PROCEDURE
The RWAL system contains 13 diagnostic trouble
codes
for system troubleshooting. With the ignition
key turned
ON, momentarily grounding the RWAL
diagnostic lead
with the "Rr ABS" light on will cause the
light
to flash out a diagnostic trouble code if a failure
has been detected and is in memory.
Some RWAL
diagnostic trouble codes require a road test in order
to
be set into the EBCM memory.
RWAL diagnostic trouble codes are cleared from
the
EBCM memory every time the ignition key is
turned off. If a diagnostic trouble code is not present, a
test drive
must be performed to reproduce the failure
and reset the code into
memory:
TEST DRIVING
1. Conduct a visual check of the following items to
see if any abnormalities exist:
(a) Service brake mechanism/hydraulic system
(See BRAKE SERVICING SECTION).
(b) Fuses #2, #7, #14 and main fuse
(c) RWAL-related connector (check for loose pins
and rust)
(d) EBCM and valve ground (check for looseness
and rust)
NOTE:
Check
(c) and (d) should be done with ignition key
turned
OFF.
If any abnormality is found, perform repairs as
required.
2. Turn the ignition switch ON. As a self-check, the
"Rr ABS" light should come on for approximately
2 seconds, then go
off and remain off.
If the "Rr ABS" light remains on or comes back
on, check
for diagnostic trouble codes by
momentarily grounding the RWAL diagnostic
lead
with the "Rr ABS" light on. -
If the "Rr
ABS" light self-check operates
properly, continue
with the test drive below.
3. Test driving vehicle:
(a) Start the engine and begin driving the vehicle.
(b) Accelerate to 40 mph.
(c) At least once, brake to a full stop using enough
brake pedal force
to activate the RWAL
system.
(d) Accelerate to 60 mph and continue to run at
this speed
for 5 minutes.
4. If a diagnostic trouble code is obtained.
inspect in accordance
with the appropriate
"FLASHOUT DIAGNOSTIC TROUBLE CODES
CHART".
If
no diagnostic trouble code is found, and the
"Rr ABS" and "BRAKE" light comes on, or if
any abnormal operation occurs during the
test drive, inspect in accordance
with CHART
C, "Rr ABS AND BRAKE LIGHTS ON".
5. If the "Rr ABS" or "BRAKE" light does not come
during the test drive, ask the customer under
what conditions the light came on. Then try to
duplicate the complaint condition
as closely as
possible.
If no problem is found, check all underhood
connections that supply power
to the RWAL and
ignition fuses, inspect
all RWAL harness
connectors, and inspect the
EBCM and anti-lock
valve ground connections.
Do not assume that the
EBCM is bad because the
"Rr ABS" or "BRAKE" lights are on. In most cases,
it is telling you it has found a problem elsewhere.
Fig. 5A3-7

5A3-38 REAR WHEEL ANTILOCK BRAKE SYSTEM
ON-VEHICLE SERVICE ·
REAR WHEEL ANTILOCK ELECTRONIC BRAKE CONTROL MODULE (EBCM)
REPLACEMENT
3
Removal steps
1. Shift knob
2. Front console assembly
3. Lower cluster assembly
4. EBCM assembly
5. Bracket
Installation steps
To install, follow the removal steps
in the reverse order.
Fig. 5A3-9
E) REMOVAL
1.
2.
3.
4.
5.
Shift knob
Front console assembly
• To remove the front console, refer to section 10
"Body".
Lower cluster assembly
EBCM assembly
• Disconnect the EBCM connector from EBCM.
•
Remove four EBCM fixing bolts.
Bracket
• Disconnect the bracket from EBCM.
1•+1 INSTALLATION
5.
4.
Bracket
• Connect the bracket to the EBCM.
EBCM assembly
• Tighten the EBCM assembly fixing bolts to the
specified torque.
I~I_T_o_rq_u_e ____ N·_m_(lb_·i_n_) ...... 1 __ 8_(6_9_) __
3.
2.
1.
Lower cluster assembly
Front console assembly
Shift knob
•

REAR WHEEL ANTILOCK BRAKE SYSTEM 5A3-39
ANTILOCK (ISOLATION/DUMP) VALVE REPLACEMENT
3
Removal steps
1. Harness connector
2. Brake pipe
3. Bolt
4. Antilock
valve 5. Bracket
Installation steps
To install, follow the removal
steps in the reverse order.
Fig. 5A3-10
NOTE:
The antilock valve is not serviceable. It should be
replaced when necessary.
EJ REMOVAL
1. Harness connector
2. Brake pipe
3. Bolt
4. Antilock valve
5. Bracket
1••1 INSTALLATION
To install, follow the removal steps in the reverse
order, noting the
following points;
1. Tighten the antilock valve fixing bolts to the
specified torque.
1~1 Bolt Torque N·m (lb·ft) I 24 (18)
2. Tighten the brake pipes to the specified torque.
1~1 Brake Pipe Torque N·m (lb·in) I 12 (104)
• Bleed the brake system as outlined in uHydraulic
Brakesu (Sec. 5A).