lock ISUZU TROOPER 1995 Workshop Manual

5A3-36 REAR WHEEL ANTILOCK BRAKE SYSTEM
Continued from the previous page
I
I CONSTANT READING OF VOLTAGE I CONSTANT READING OF VOLTAGE I ERRATIC VOLTAGE READING. I OVER 9 VOLTS UNDER 9 VOLTS
I CHECK EBCM AND STOPLIGHT I REPAIR WIRE FOR OPEN CIRCUIT I REPAIR THE HARNESS. I CIRCUIT CONNECTIONS. BETWEEN STOPLIGHT SWITCH AND EBCM AND RECHECK THE SELF CHECK.
I
I NO PROBLEM EBCM AND STOPLIGHT CIRCUIT J I REPAIRCONNECTION(S),ERASETROUBLECODEANDTHEN I CONNECTIONS. RECHECK THE SELF CHECK AND RETEST VEHICLE.
I CONNECT EBCM HARNESS CONNECTOR THEN TURN I IGNITION ON.
l
I NO CODE 11 INDICATED I I CODE 11 RETURNS J
I I REFER TO NOTE ON PREVIOUS PAGE, ERRONEOUS CODE l I REPLACE EBCM AND RECHECK THE SELF CHECK. I MAY BE CAUSED BY "RIDING" THE BRAKE PEDAL.
EBCM = Electronic Brake Control Module
•

REAR WHEEL ANTILOCK BRAKE SYSTEM 5A3-37
FLASHOUT DIAGNOSTIC TROUBLE CODE 13/14/15
(EBCM FAILURE)
• REPLACE THE EBCM AND RECHECK SELF CHECK.
EBCM -Electronic Brake Control Module

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).

5A3-40 REAR WHEEL ANTILOCK BRAKE SYSTEM
SPEED SENSOR REPLACEMENT
Removal steps
1. Harness connector
2.
Bolt and washer
3. Speed sensor
Installation steps To install, follow the removal
steps in the reverse order.
Fig. 5A3-11
NOTE:
The speed sensor is not serviceable. It should be
replaced when necessary.
E3 REMOVAL
1. Harness connector
2. Bolt and washer
3. Speed sensor
1••1 INSTALLATION
To install, follow the removal steps in the reverse
order, noting the
following points;
1. Tighten the bolt to the specified torque.
1~1 Bolt Torque N-m {lb·ft) I 24 {18)
NOTE:
See "Rear Axle" {Sec. 48) for exciter ring service.

REAR WHEEL ANTILOCK BRAKE SYSTEM 5A3-41
MAIN DATA AND SPECIFICATIONS
TORQUE SPECIFICATIONS N·m (lb·ft)
Fig. 5A3-12

4-WHEEL ANTILOCK BRAKE SYSTEM (ABS) 5A4-1
SECTION 5A4
'--' 4-WHEEL ANTILOCK BRAKE SYSTEM (ABS)
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 .................... 5A4-3
System Components ................. 5A4-3
Electronic Brake
Control Module ·
(EBCM) .......................... 5A4-3
Hydraulic Unit ...................... 5A4-3
ABS Warning Light .................. 5A4-4
Wheel
Speed Sensor ................. 5A4-4
G-Sensor
........................... 5A4-4
Normal and Antilock Braking .......... 5A4-4
Brake Pedal Travel
................... 5A4-4
Abbreviation ........................ 5A4-4
Diagnosis
............................. 5A4-5
General
Information ................. 5A4-5
ABS
System Service Precautions ....... 5A4-5
Computer System Service
Precautions
....................... 5A4-5
General Service Precautions
........... 5A4-5
Note on lntermittents ................ 5A4-6
Test Driving ABS Complaint Vehicles ... 5A4-6
II ABS11 Warning Light ................ 5A4-6
Normal Operation ................... 5A4-6
Basic
Diagnostic Flow Chart ........... 5A4-7
Basic
Inspection Procedure ............ 5A4-8
TECH 1
TOOL. ......................... 5A4-10
1. What can be done with TECH 1 ...... 5A4-10
2. How to Use TECH 1 ................ 5A4-11
3. Explanation of Modes .............. 5A4-15
Mode FO: Data List ................... 5A4-16
Mode F2: Trouble Code ............... 5A4-18
Mode F3: Snapshot .................. 5A4-19
Mode F4: Clear Code ................. 5A4-20
Mode F5: Actuator Test ............... 5A4-21
Mode F6: Wheel Sensors ............. 5A4-31
Pin-Out Checks ........................ 5A4-33
Circuit Diagram ..................... 5A4-34
Part Location ....................... 5A4-37
Symptom Diagnosis .................... 5A4-38
CHART A-1 1) ABS Works Frequently
but Vehicle does not Decelerate ...... 5A4-39
CHART TA-1 1) ABS Works Frequently
but Vehicle does not Decelerate ...... 5A4-40
CHART A-2 2) Uneven Braking Occurs
while ABS Works .................. 5A4-41
CHART TA-2 2) Uneven Braking Occurs
while ABS Works .................. 5A4-42
CHART A-3, T A-3 3) The Wheels are
Locked
........................... 5A4-43
CHART A-4 4) Brake Pedal Feel is
Abnormal ........................ 5A4-44
CHART A-5 , T A-5 5) Braking Sound
(from Hydraulic Unit) is Heard while
not Braking ....................... 5A4-45
Diagnosis by 11 ABS11 Warning Light
Illumination Pattern .................. 5A4-46
Diagnostic Trouble Codes (DTCs) ....... 5A4-47
1. How to Display and Erase DTCs ... 5A4-47
2. Diagnostic Trouble Codes ........ 5A4-49
CHART B-1 With the Key in the ON
Position (before Starting the Engine),
Warning Light (W /L) is not
•
Actuated ........................ 5A4-50
CHART B-2 II ABSII Light Flashes
Twice with Key ON ................ 5A4-51
CHART B-3 EBCM Abnormality (Diagnostic
Trouble Code 14) .................. 5A4-52
CHART B-4 Power Voltage Drop (Diagnostic
Trouble Code 15) .................. 5A4-53
CHART B-5 G-Sensor Circuit (Diagnostic
Trouble Code 21) .................. 5A4-54
CHART B-6 Brake Switch Trouble
(Diagnostic Trouble Code 22) ........ 5A4-55
CHART B-7 Abnormal Transmission Input
(A/T Modei)(Diagnostic Trouble
Code 23) ......................... 5A4-56
CHART B-7 Abnormal Transmission Input
(M/T Modei)(Diagnostic Trouble
Code 23) ......................... 5A4-57
CHART B-8 Hydraulic Unit (HU) Pump
Motor and Motor Relay Circuit
(Diagnostic Trouble Code 32) ........ 5A4-58
CHART B-9 Solenoid Valve Abnormality
(Diagnostic Trouble Code 41, 42,
& 44) ............................ 5A4-59
CHART B-10 Valve Relay Abnormality
(Diagnostic Trouble Code 45) ........ 5A4-60

5A4-2 4-WHEEL ANTILOCK BRAKE SYSTEM (ABS)
CHART B-11 Speed Sensor Disconnection
(Diagnostic
Trouble Code
51, 52, 53, & 54) ................... 5A4-61
CHART B-12 Speed Sensor Short Circuit
(Diagnostic Trouble Code
61, 62,

63,
& 64) ................... 5A4-62
CHART B-13, TB-13 Sensor Signal Input
Abnormality (Diagnostic Trouble
Code
65) ......................... 5A4-63
Unit Inspection Procedure ............... 5A4-64
CHART C-1 G-Sensor Unit Inspection
Procedure ........................ 5A4-65
CHART C-2 Sensor Output Inspection
Procedure ........................ 5A4-66
CHART TC-2 Sensor Output Inspection
Procedure ........................ 5A4-67
CHART C-3 4WD Switch Inspection
Procedure ........................ 5A4-68
CHART TC-3 4WD Switch Inspection
Procedure ........................ 5A4-69
CHART C-4 Transmission Input
Inspection Procedure (A/T Modell .... 5A4-70
CHART C-4 Transmission Input
Inspection Procedure (M/T Model) .... 5A4-71
CHART TC-4 Transmission Input
Inspection Procedure ............... 5A4-72
On-Vehicle Service ..................... 5A4-73
Hydraulic Unit ...................... 5A4-73
Electronic Brake Control Module
(EBCMI .......................... 5A4-74
G-Sensor ........................... 5A4-75
Front Wheel Speed Sensor ............ 5A4-76
Rear
Wheel Speed Sensor ............ 5A4-78
Special Tools .......................... 5A4-79
..

4-WHEEL ANTILOCK BRAKE SYSTEM (ABS) 5A4-3
GENERAL DESCRIPTION
The Antilock Brake System (ASS) works on all four
wheels. A combination of wheel speed sensor and
Electronic Brake Control Module (EBCM) can
determine
when a wheel is about to stop turning
and adjust brake pressure to maintain best braking.
This system
helps the driver maintain greater
control of the vehicle under heavy braking
conditions.
Master Cylinder
I I I I
--------Electric
===== Hydraulic
,--1 I
I
I
-ld4
1. Hydraulic unit 2. Electronic brake control module (EBCM)
3. Front wheel speed sensor 4. Rear wheel speed sensor
5. G-sensor 6. Proportioning and bypass (P&Bl valve
(Refer to "Hydraulic Brakes"(Sec. 5A).)
Fig. 5A4-1
SYSTEM COMPONENTS
The Antilock Brake System consists of a Hydraulic
Unit, Electronic Brake Control Module (EBCM), four
Wheel Speed Sensors, Warning Light, and G­
sensor.
ELECTRONIC BRAKE CONTROL MODULE
(EBCM)
The EBCM consists of ABS control circuits, fault
detector, and a fail-safe. It drives the hydraulic unit
according to the signal from each sensor,
cancelling ABS to return to normal braking when a
malfunction has occurred in the ABS.
The EBCM is self-diagnosing function can indicate
faulty circuits during diagnosis.
'--" HYDRAULIC UNIT
The hydraulic unit is mounted on the engine room
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 calip~r fluid
pressure for each front disc brake or both rear disc
brakes according
to the signal sent from the EBCM.
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 EBCM.
Check
Valve; Controls the brake fluid flow.

5A4-4 4-WHEEL ANTILOCK BRAKE SYSTEM (ABS)
ABS WARNING LIGHT
Vehicles equipped with the Antilock Brake System
have an
amber "ABS" warning light in the
instrument panel. The "ABS" warning light will
illuminate if a malfunction in the Antilock Brake
System is detected by the Electronic Brake
Control
Module (EBCM). In case of an electronic
malfunction, the EBCM will turn "ON" the "ABS"
warning light and disable the Antilock braking
function.
The
"ABS" light will turn "ON" during engine
starting and
will usually stay "ON" for
approximately three seconds after the ignition
switch is returned to the "ON" position.
If the "ABS" light stays "ON" after engine start-up,
or comes "ON" and stays "ON" while driving, the
Antilock Brake System should be inspected
for a
malfunction according to the diagnosis procedure.
Fig. 5A4-2
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
"sine curve" 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 EBCM. It is normally on, and is turned
off when the vehicle deceleration speed exceeds
about 0.35G.
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
EBCM's operating system to ensure ABS control.
NORMAL AND ANTILOCK BRAKING
Under normal driving conditions, the Antilock 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
"bump" 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 antilock function or until the vehicle is
stopped. A
slight ticking or popping noise may be
heard
during brake applications when the Antilock
features is being used.
When the
Antilock 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 Antilock 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.
ABBREVIATIONS
Several abbreviations are commonly used
throughout this section:
ABS .......................................... Antilock Brake System
CKT ...................................................................... Circuit
DLC ............................................... Data Link Connector
EBCM ....................... Eiectronic Brake Control Module
FL. ................................................................... Front Left
FR ................................................................. Front Right
GEN ............................................................... Generator
HU .......................................................... Hydraulic Unit
MV ................................................................... Millivolts
RL .................................................................... Rear Left
RR ................................................................. Rear Right
RPS .......................................... Revolution per Second
UVR ............................................................. Valve Relay
VDC .................................................................. DC Volts
VAC .................................................................. AC Volts
W/L .........................................................
Warning Light
WSS ............................................ Wheel Speed Sensor