light ISUZU TROOPER 1995 Owner's Guide

5A-1 0 HYDRAULIC BRAKES
8. Turn the ignition key off.
• If the warning light does not come on during
steps 3 and
6, but does light when a jumper is
connected to ground, the warning switch
portion
of the valve is faulty. Do not
disassemble any portion of the valve. It must
be replaced.
9. Remove the safety stands.
• Lower the vehicle.
• Check and fill the master cylinder to the proper
level.
VALVE REPLACEMENT
Removal steps 1. Hydraulic pipes
2. Warning switch
connector (Combination valve only)
3. Bolt
4. Combination valve/P&B valve
Installation
steps
To install, follow the removal steps in the reverse order.
Fig. 5A-5
1••1 REMOVAL
• The combination valve/P & 8 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.
1. Hydraulic pipes
• Plug the pipes to prevent the loss of fluid or the
entrance
of dirt.
2. Warning switch connector (Combination valve
only)
3. Bolt
4. Combination valve/P & B valve
1••1 INSTALLATION
4.
3. Combination valve/P & B valve
Bolt
I~I_T_o_r_qu_e_N_·_m_(lb_·_in_) ___,_ ___ 1_3_(_1_13_) __ _
2. Warning switch connector (Combination valve
only)
1. Hydraulic pipes
~~~ Torque N·m (lb·ft) 16 (12)
After installing the brake pipes, bleed brakes as
described in this section.
•

INSPECTION OF BRAKE PAD LINING
(Fig. SA-6)
Inspect the brake linings any time the wheels are
removed (tire rotation, etc.). Check both ends
of the
outer pad by
looking at each end of the caliper. These
are the points at which the highest rate
of wear
normally occurs. At the same time, check the lining
thickness on the inner shoe to make sure that it was not
worn prematurely. Some inboard shoes and linings
have a thermal layer against the shoe, integrally
molded
with the lining. This extra layer should not be
confused with uneven inboard-outboard lining wear.
Look
down through the inspection hole in the top of the
caliper to view the inner shoe. Whenever the thickness
of any lining is worn to within 1 mm (0.039 in) of the
shoe,
all disc brake pad and lining assemblies should
be replaced at the same time.
The disc pads have a
wear indicator that makes a noise
when the pad wear to a degree where replacement is
required.
100
Limit 11.0 mm (0.039 in) I
Fig. 5A-6
INSPECTION OF BRAKE ROTORS
In manufacturing the brake rotor, tolerances of the
braking surfaces
for flatness, parallelism and lateral
runout are held very close. The maintenance of close
tolerance
on the shape of the braking surfaces is
necessary to prevent brake roughness.
In addition to these tolerances, the surface finish must
be held to a specified range. The control ofthe braking
surface finish is necessary to avoid
pulls and erratic
performance and to extend
lining life.
Light scoring of the rotor surfaces not exceeding
0.38mm (0.015 in) in depth, which may result from
normal use, is not detrimental to brake operation.
Thickness Variation Check (Fig. 5A-7)
1. Thickness variation can be checked by measuring
the thickness
of the rotor at four or more points
around the circumference
of the rotor. All
measurements must be made at 29 mm (1.14 in)
front/22 mm (0.87 in) rear from the edge of the
rotor.
HYDRAULIC BRAKES 5A-11
Fig. 5A-7
~~~ Front Disc Brake Rotor Thickness
Standard mm (in) 26.0 (1.024)
Limit mm(in) 24.6 (0.969)
~~~Rear Disc Brake Rotor Thickness
Standard mm (in) 18.0 (0.709)
Limit mm (in) 16.6 (0.654)
2. A rotor that varies by more than 0.010 mm
(0.0004 in) can cause pedal pulsation and/or front
end vibration during brake applications. A rotor
that does not meet these specifications should be
refinished
to specifications or replaced.
Lateral Runout Check (Fig. 5A-8)
1. Adjust the wheel bearing correctly.
• Refer to "Front Drive Axle" in Section 4C.
2. Install 2 wheel nuts to retain rotor.
3. Fasten a dial indicator to the suspension so that
the indicator stylus contacts the rotor about
29 mm (1.14 in)-front/22 mm (0.87 in)-rear from
the rotor edge.
4. Zero the dial indicator.
5. Move the rotor one complete revolution and
observe
total indicated runout.
Fig. 5A-8

HYDRAULIC BRAKES SA-13
BRAKE PEDAL ASSEMBL V
CHECKING PEDAL HEIGHT (Fig. SA-1 0)
The push rod serves as the brake pedal stopper when
the pedal is fully released. Brake pedal height
adjustment
should be performed as follows:
I~FI Adjust brake pedal
1. Measure the brake pedal height after making sure
the pedal is
fully returned by the pedal return
spring. Pedal height
(L2) must be measured after starting
the engine and revving
it several times (Fig. 5A-
10).
1~1 Pedal Free Play (L 1) mm (in) 6-10 (0.23- 0.39)
Pedal Height (L2)
NOTE:
mm (in) 208-218
(8.19-8.58)
Pedal free play (L 1) 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 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 N·m (lb·ft) 20 (15) --------~----~---
Fig. 5A-10
g) Adjust the stoplight switch to the specified
clearance (between switch housing and brake
pedal)
by rotating the switch housing (Fig. 5A-
11 ).
1@1 Clearance mm (in) I 0.5-1.0 (0.02-0.04)
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.
Fig.
5A-11
CHECKING PEDAL TRAVEL (Fig. SA-1 0)
1. Pedal height (L3) must be measured after starting
the engine and revving
it several times to apply
vacuum
to the vacuum booster fully.
NOTE:
Pedal height (L3) must be 55 mm (2.2 in) or more when
about 50 kg (11 0.25 I b) of stepping force is applied.
2. If the measured value is lower than the above
range, air existing in the hydraulic system is
suspected and perform bleeding procedure.

5A-14 HYDRAULIC BRAKES
BRAKE PEDAL REPLACEMENT
5
3
1
13
Removal steps MIT
1. Shift knob 6. Anti-theft controller 12. Pin, fulcrum
2. Front console assembly 7. Stoplight switch connector 13. Brake pedal
3. Lower cluster assembly
4.1nstrument panel
driver lower
cover
5. Driver knee bolster assembly
8. Return spring
9. Snap pin
10. Pin
11. Nut
Installation steps
To install, follow the removal steps
in the reverse order.
Fig. 5A-12
EJ REMOVAL
1. Shift knob
2. Front console assembly
3. Lower cluster assembly
4. Instrument panel driver lower cover
5. Driver knee bolster assembly
6. Anti-theft controller
7. Stoplight switch connector
8. Return spring
9. Snap pin
10. Pin
11.
Nut
12. Pin, fulcrum
13. Brake pedal
1•+1 INSTALLATION
13.
Brake pedal
12. Pin, fulcrum
§)• Apply grease to the entire circumference of the
fulcrum pin.
~~~ Torque N·m (lb·ft) ___ __._ ___ _ 33 (24)
11. Nut
~~~--T-o-rq_u_e __ N-.m--(-lb-.ft-)-.-----3-3-(-24_) ____ _
10. Pin
r:::;:] • Apply grease to the entire circumference of the
D push rod pin. ·
9. Snap pin
f;C1 • Adjust pedal free travel. Refer to "Brake Pedal
lED Adjustment" previously in this section.
8. Return spring
7. Stoplight switch connector
6. Anti-theft connector
5. Driver knee bolster assembly
4. Instrument panel driver lower cover
3. Lower cluster assembly
2. Front console assembly
1. Shift knob
•

STOPLIGHT SWITCH REPLACEMENT
1
3 MIT
h
4
HYDRAULIC BRAKES SA-15
Removal steps
1. Shift knob
2. Front console assembly
3. Lower cluster assembly
4. Instrument panel driver
lower cover
5. Driver knee bolster
assembly
6. Stoplight switch
connector
7. Lock nut
B. Switch
Installation steps
To install, follow the removal
steps in the reverse order.
Fig. 5A-13
1••1 REMOVAL
1. Shift knob
2. Front console assembly
3. Lower cluster assembly
4. Instrument panel driver lower cover
5. Driver knee bolster assembly
6. Stoplight switch connector
7. Lock nut
8. Switch
1••1 INSTALLATION
8. Switch
• Adjust the stoplight switch to the specified
clearance (between switch housing and brake
pedal) by rotating the switch housing (Fig. 5A-
14).
~~~ Clearance mm (in) J 0.5 -1.0 (0.02 -0.04)
NOTE:
While adjusting the installation of the stoplight switch,
make sure that the threaded part
ofthe stoplight switch
does
not push the brake pedal.
Fig. 5A-14
7. Lock nut
6. Stoplight switch connector
5. Driver knee bolster assembly
4. Instrument panel driver lower cover
3. Lower cluster assembly
2. Front console assembly
1. Shift knob

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 5A3-3
ELECTRONIC BRAKE CONTROL MODULE
(EBCM)
The electronic brake control module is microprocessor
based and is located on the
front end of the center
Power source
console. It performs three different algorithms to
calculate excessive wheel deceleration and performs
self check diagnostics.
Ground
~
Wheel speed sensor TACHOMETER
ALGORITHM
Valve reset
Brake
switch
PERFORMANCE
ALGORITHM o-+ ...
Isolation solenoid
Dump solenoid
SELF CHECK AND FAILSAFE
ALGORITHM
Differential switch, br<'!ke warning light
~
Fig. 5A3-2
ANTILOCK (ISOLATION/DUMP) VALVE
The antilock (dual solenoid hydraulic) valve is located
between the rear brakes and the combination valve
and is attached on the
front right side of engine room.
The valve contains
an isolation valve, dump valve and
an accumulator and is electrically connected to the
electronic control module.
The normal positions
for the antilock valve com­
ponents are
as follows;
1. Isolation valve is normally open (flow through
under normal braking).
2. Dump valve is normally closed.
3. Accumulator is empty.
Once the rear wheel antilock is activated, the EBCM
closes the isolation valve. If closing of the isolation
valve is insufficient to prevent wheel lock, the
EBCM
will open the dump valve to allow some rear brake fluid
into the accumulator, thus reducing brake pressure.
The
EBCM will continue to monitor wheel deceleration,
and
if it is still excessive will cause the antilock valve to
dump fluid to the accumulator again. This process will
be repeated until the appropriate wheel speed
correction is calculated by the
EBCM.
When the brake pedal is released, the isolation valve
de-energizes and any fluid in the accumulator is
returned to the master cylinder.
Normal brake operation is resumed.
Fig. 5A3-3

REAR WHEEL ANTILOCK BRAKE SYSTEM 5A3-5
REAR WHEEL ANTILOCK (RWAL} CONTROL PARTS LOCATION
Fig. 5A3-5
ELECTRONIC BRAKE CONTROL MODULE
The module is located at the front of the center console.
ANTILOCK VALVE (Dual solenoid electrohydraulic)
The valve is located on the front right side of engine room.
SPEED SENSOR/EXCITER RING
The sensor and exciter ring are located on the rear axle carrier.
REAR WHEEL ANTILOCK (RWAL) WARNING LIGHT
The light is located on the instrument panel.
Rear axle
Electronic
brake control module

5A3-6 REAR WHEEL ANTILOCK BRAKE SYSTEM
SYSTEM DIAGRAM
4WD
switch
To 4WD
light -----11~-----lGY 3
Diagnostic Of------0 7 connector
For test
1-----11---+--y 17 Speed
sensor 1-----lt-----L
16
To
stoplight -----,
Stoplight switch
•IJI-----B 15
EBCM Pin View
i
&l ~ IU _, :;) Q
~ _, 0 a: .... z
8 IU ~ c( a: liD (.) z 0 a: 1-(.) IU _, IU
Pressure differential warning switch
(at Combination valve)
r-----+-<1 ~+II•
I•
6 LgB Parking brake _.-MI ____ ___,I'\.JI.Jr-, switch
5
BP -----'
2 w ------------~~._~
GR
4 BrR
9 BrY
20A Fuse F-9
RWAL 10
A •
1• h Fuse C-10
warnmg IQ t (Instrument
Antilock valve panel)
Isolation
valve
~ 4il .J o--1> ~
Reset ~1.5il
I
sw.
Dump valve
(Engine compartment)
13 YG - ACC IG1 Ignition
82 81 switch
50 A
Batt.
10 GW + ,,
15A BOA Fuse C-14 Main (Instrument fuse panel)
RWAL=Rear Wheel Antilock
CONNECTOR View
Fig. 5A3-6
•

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