relay ISUZU TROOPER 1995 Owner's Manual

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

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

4-WHEEL ANTILOCK BRAKE SYSTEM (ABS) 5A4-15
3. EXPLANATION OF MODES
Mode FO: OAT A LIST
FO: DATA LIST can display the
conditions
of sensors and switches as
well as the ONfOFF operation of
solenoid valves as commanded by the
EBCM.
In case of system abnormality,
the trouble area can be roughly
identified
with the data displayed.
Mode
F2: TROUBLE CODE
F2: TROUBLE CODE can display the
past (history) Diagnostic Trouble Codes
(DTCs) stored
by the EBCM. When
some
trouble occurs and a TROUBLE
CODE is set in this mode, the faulty
area can
promptly be located by
checking the associated Trouble Code
No.
Mode
F3: SNAPSHOT
F3: SNAPSHOT can help locate the
cause
of trouble by storing and
displaying the data
from a specific
period
of vehicle operation.
Mode
F4: CLEAR CODES
F4: CLEAR CODES erases the DTC
stored by the control unit.
Mode F5: ACTUATOR TEST
F5: ACTUATOR TEST can make sure if
the system-related motor, solenoid
valves, and hydraulic circuit function
normally. If there is still a problem in
the operation of the system even after
making electrical repairs, ACTUATOR
TEST may uncover another problem.
(note
1) This mode can be used under
the
following conditions:
No
trouble code is stored. (note 1)
The vehicle is not in motion. (note 2)
This mode should be selected before
starting the engine.
note
1: As this mode forcibly operates
actuators (solenoid valves,
relays, motor, etc.), the control
unit may be damaged if this
test
is conducted on damaged
actuators. Therefore, be sure
to repair all electrical faults
and make sure no
DTC is
stored before using this mode. note
2: If a vehicle speed (30 km/h
(18.6
mph)
or more) is detected
during the ACTUATOR
TEST,
the test function will auto­
matically stop.
Mode
F6: WHEEL SENSORS
F6: WHEEL SENSORS can check to
detect such speed sensor trouble as
EBCM's self-diagnosing function fails to
detect, including excessive gap in each
speed sensor,
momentary cut-off of
sensor signal, etc.

5A4-16 4-WHEEL ANTILOCK BRAKE SYSTEM (ABS)
MODE FO: DATA LIST (When connected (communication with EBCM) while warning light is
off)
The data displayed by MODE FO: OAT A LIST are as follows:
Display Content OK/NG Criteria for Data
FL WHEEL SPEED km/h (mph) • Start the vehicle and make sure of linear change in each
FR WHEEL SPEED wheel speed.
• Turn each wheel by hand and make sure that each speed RL WHEEL SPEED data changes.
RR WHEEL SPEED
UVR MONITOR
Voltage • About 5V with key ON
VALVE RELAY INACTIVE • ACTIVE with key ON
ACTIVE
Voltage •
About 5V with brake pedal
BRAKE SWITCH • About OV with brake pedal
released
OPEN (Released)
• CLOSE
with brake pressed
CLOSE (Pressed) • OPEN with brake pedal released
ABSWARNING ACTIVE
• To be ACTIVE usually
LIGHT
INACTIVE
WHL. SENSOR RES. FAULT • Normal, if OKAY
OKAY
-FL SOL. VALVE ACTIVE • To be INACTIVE usually
FR SOL. VALVE INACTIVE
REAR SOL. VALVE
P. MOTOR RELAY ACTIVE • To be INACTIVE usually
INACTIVE
OFF-ROAD-INPUT Voltage A/T 1 L, R: less than O.SV
Other: 3 ±O.SV
MIT 1, 2, R: more than 4.0V
Other:
3 ± O.SV
T/F SWITCH OPEN • 4WD: CLOSE
CLOSE •
2WD: OPEN
As for ABS vehicle speed unit, km/h and mph are displayed alternately through Key F7.
•

4-WHEEL ANTILOCK BRAKE SYSTEM (ABS) 5A4-17
MODE FO: DATA LIST (When connected (communication with EBCM) while warning light is
on)
._,. The data displayed by MODE FO: DATA LIST are as follows:
Display
Content OK/NG Criteria for Data
FL WHEEL SPEED
km/h (mph) • Start the vehicle and make sure of linear change in each
FR WHEEL SPEED wheel speed.
• Turn each wheel by hand and make sure that each speed RL WHEEL SPEED data changes.
RR WHEEL SPEED
UVR MONITOR Voltage • About OV with key ON
VALVE RELAY INACTIVE • INACTIVE with key ON
ACTIVE
Voltage • About 5V with brake pedal
BRAKE
SWITCH • About OV with brake
pedal released
OPEN (Released) • CLOSE with brake pressed
CLOSE (Pressed) • OPEN with brake pedal released
ABSWARNING ACTIVE • To be ACTIVE usually
LIGHT
INACTIVE
WHL.
SENSOR RES. FAULT • Normal, if OKAY
OKAY
FL SOL. VALVE ACTIVE • To be ACTIVE usually
FR SOL. VALVE INACTIVE
REAR SOL. VALVE
P. MOTOR RELAY
ACTIVE • To be INACTIVE usually
INACTIVE
OFF-ROAD-INPUT Voltage A/T 1 L, R: less than 0.5V
Other:
3 ±0.5V
MIT
1, 2, R: more than 4.0V
Other:
3 ± 0.5V
T/F SWITCH OPEN • 4WD: CLOSE
CLOSE •
2WD: OPEN
As for ABS vehicle speed unit, km/h and mph are displayed alternately through Key F7.

5A4-18 4-WHEEL ANTILOCK BRAKE SYSTEM (ABS)
MODE F2: TROUBLE CODE
The stored diagnostic trouble codes and their brief explanations are displayed in Mode: F2.
NOT PRESENT ...... Now normal, though faulty before.
PRESENT ............... Now faulty
NO TROUBLE CODES
ABS-2E
NO TROUBLE CODES
CHART 2 TROUBLE CODE
Code Code
12 Start code
14 EBCM function
15 Power voltage drop
21 G-sensor
22 Brake light switch
23 Transmission input
32 Motor&motor relay
41 FL wheel valve
42 FR wheel valve
44 Rear wheel valve
SELECT MODE FO:DATA LIST
F1: NOT USED F2:TROUBLE CODE
I
l (F2)
TC51:NOT PRESENT FRONT LEFT
WHEEL SENSOR OPEN (YESJ
(YES) J--_j
ABS-2E TC NOT PRESENT
51. 52, 62 SEE CHART 2 (YESJ
(YES)
l
SELECT MODE FO: DATA LIST
Fl:NOT USED F2:TROUBLE CODE
Chart No.
-
B-3
B-4
B-5
B-6
B-7
B-8
B-9
All the diagnostic trouble codes
and
their explanations stored by
EBCM are displayed.
On completion of displaying all the
diagnostic trouble codes and
their
explanations, all the diagnostic
trouble codes
only will be
displayed again.
Code Code
45 Valve relay
51 FL wheel speed sensor
52 FR wheel speed sensor
53 RL wheel speed sensor
54 RR wheel speed sensor
61 FL wheel speed sensor
62 FR wheel speed sensor
63 RL wheel speed sensor
64 RR wheel speed sensor
65 Sensor signal input
Chart No.
B-10
B-11
B-12
B-13
•

4-WHEEL ANTILOCK BRAKE SYSTEM (ABS) 5A4-21
MODE F5: ACTUATOR TEST
This mode is used to exercise the ABS system actuators and make sure they operate normally. Prior to the
test, pay attention
to the cautions below. (When checking the solenoid valve system, be sure to jack up the
vehicle.)
w CAUTION:
• Before testing, be sure that the brakes work normally.
• Make sure that the battery is fully charged.
Conduct the test
by two persons (A TECH 1 operator and a vehicle checker).
• Be sure to start actuator test with the engine stopped.
• Before testing, make sure that electrical trouble, if any, has been completely repaired. Conducting
tests
of ABS actuator with electrical circuit problem remaining uncorrected could damage the
control unit.
Selection Procedure:
SELECT MODE FO:DATA LIST
*
F5:ACTUATOR TEST
IUiJ
SELECT ACTUATOR * P. MOTOR RELAY FL SOL. VALVE
FR SOL. VALVE REAR SOL. VALVE
ABS W/L
----> Refer to CD
----> Refer to ®
----> Refer to @ ----> Refer to @
----> Refer to ®
NOTE:
F5; Actuator test procedure, the systems Q) to @
mentioned on the left can be checked four times
continuously as each system is checked once.
When checking more than
four times continuously,
the fifth check
must be started with a break of 10
minutes or more after the fourth to protect ABS
pump motor.
Select the desired test
by operating !I] 1[!] keys and press I ENT I key.

5A4-22 4-WHEEL ANTI LOCK BRAKE SYSTEM (ABS)
(j): Pump Motor Relay Test
The pump motor operates when current flows through the pump motor relay coil (Fig. 5A4-9).
PUMP
MOTOR
~ II
....----
EBCM ~ .____
MOTOR RELAY
Fig. 5A4-9
Confirm the operation of the pump motor by its operating sound in the engine compartment.
TECH 1 Display Key Operation
Display 1 Is the pump motor working ? If so, press the YES key. If not, press the NO
key. (The pump motor works for about 5 seconds.)
P.MOTOR RELAY
COMMANDED ON * If the YES key is pressed, the menu display will be returned.
OKAY ?
(YES/NO)
If the NO key was pressed above
Display 2
A test failure.
The pump motor has mechanical trouble.
P.MOTOR RELAY
TEST FAILED * If the YES key is pressed, the menu display will be returned.
(YES)
If the YES or NO key was not pressed within 5 sec. on Display 1 above
Display 3
Did the pump motor work normally?
If so, press the YES key. If not, press the NO key.
P.MOTOR RELAY
OKAY ? * YES key c:::> Menu display
(YES/NO) *No key c:::>Display 2
•

5A4-24 4-WHEEL ANTILOCK BRAKE SYSTEM (ABS)
®: Front left wheel brake system test
TECH 1 Display
Key Operation Brake
pedal
BEFORE TEST RUN • Prior to the test, be sure to understand the entire OFF ON
SEE CHECKING procedure.
PROCEDURE • To go to the next step, press the YES key.
(YES)
FL SOL. VALVE Can the wheel be turned by hand?
NORMAL FUNCTION If so, press the YES key. Of not, press the NO key. (lfthe NO
WHEEL TURNABLE ? key is pressed, Diaplay 1 will be returned.)
(YES/NO)
FL SOL. VALVE Depress the brake pedal. Hold it down through the rest of
NORMAL FUNCTION this test.
DEPRESS AND HOLD
BRAKE PEDAL !
FL SOL. VALVE Is the wheel locked ?
NORMAL FUNCTION If so, press the YES key. If not, press the NO key. (If the NO
WHEEL BLOCKED ? key is pressed, Display 1 will be returned.)
(YES/NO)
FL SOL. VALVE The TECH 1 commands the EBCM to reduce hydraulic
RELEASE FUNCTION pressure and activate the pump motor. Display
p. MOTOR RELAY automatically goes to next display after a few seconds.
Brake pressure has been reduced. Can the wheel be turned
FL SOL. VALVE by hand ? If so, press the YES key. If not, press the NO key.
RELEASE FUNCTION (If the NO key is pressed, Display 2 will be returned.)
WHEEL TURNABLE ? Note:
(YES/NO) To protect the valve, press the YES or NO key within 10
seconds.
FL SOL. VALVE With the solenoid valve released, brake pedal pressure is
RELEASE FUNCTION allowed to reach the brake.
WHEEL BLOCKED ? Is the wheel locked ? If so, press the YES key. If not, press
(YES/NO) the NO key. (If the NO key is pressed, Display 2 will be
returned.)
(Test is over.)
•