warning ISUZU TROOPER 1995 Owner's Guide

4-WHEEL ANTILOCK BRAKE SYSTEM (ABS) 5A4-5
DIAGNOSIS
GENERAL INFORMATION
ABS troubles can be classified to two types, those
which can be detected by the ABS warning light
and those which can be detected as a vehicle
abnormality by the driver.
In either case, locate the fault in accordance with
the "BASIC DIAGNOSTIC FLOWCHART" and repair.
Please refer to Section 5A, 5A1, 5A2, 5C for the
diagnosis
of mechanical troubles such as brake
noise, brake
judder (brake pedal or vehicle vibration
felt when braking), uneven braking, and parking
brake
trouble.
ABS SYSTEM SERVICE PRECAUTIONS
Required Tools and Items
Box Wrench
• Brake Fluid
Special Tool
Some diagnosis procedures in this section require
the installation of a special tool.
PINOUT BOX
In order to prevent damage to the 35-pin Electronic
Brake
Control Module (EBCM) connector, J-35592
pinout box should be installed on the EBCM
connector prior to probing any circuit with the
digital
multimeter. This pinout box is to be used
combined with J-35616 connector test adapter kit.
W IMPORTANT
Do not probe the 35-pin EBCM connector
without installing J-35592 pinout box. Damage
to connector terminals may occur if the pinout
box is not installed, resulting in improper
system operation. The following procedure
should be used to install J-35592 pinout box.
1. Ignition must be "OFF" when installing or
removing the 35-pin EBCM connector.
Fig. 5A4-3
2. Disconnect the 35-pin EBCM harness connector
by depressing the connector locking plate and
rotating
the connector toward the front of
vehicle.
3. Inspect the 35-pin connector for damage.
Connect J-35592 to the 35-pin connector.
4. Proceed with test as outlined in the diagnostic
procedure.
J-39200 HIGH IMPEDANCE MUL TIMETER
When circuit measurements are requested, use a
circuit tester
with high impedance.
COMPUTER SYSTEM SERVICE
PRECAUTIONS
The Antilock Brake System interfaces directly with
the Electronic Brake Control Module (EBCM) which
is a
control computer that is similar in some
regards
to the Engine Control Module. These
modules are designed to withstand normal current
draws associated with vehicle operation. However,
care
must be taken to avoid overloading any of the
EBCM circuits. In testing for opens or shorts, do not
ground or apply voltage to any of the circuits unless
instructed to
do so by the appropriate diagnostic
procedure. These circuits should only be tested
with a high impedance multimeter (J-39200) or
special tools as described in this section. Power
should never be removed or applied to any control
module with the ignition in the "ON" position.
Before removing
or connecting battery cables,
fuses
or connectors, always turn the ignition switch
to the "OFF" position.
GENERAL SERVICE PRECAUTIONS
The following are general precautions which should
be observed when servicing and diagnosing the
Antilock Brake System and/or
other vehicle
systems. Failure
to observe these precautions may
result in Antilock Brake System damage.
If welding work is to be performed on the
vehicle using an electric arc welder, the EBCM
and valve block connectors should be
disconnected before the
welding operation
begins.
The
EBCM and valve block connectors should
never be connected or disconnected with the
ignition "ON".
Hydraulic units of the Antilock Brake System
are not separately serviceable and must be
replaced
as assemblies. Do not disassemble
any
component which is designated as non­
serviceable in
this Section.

5A4-6 4-WHEEL ANTILOCK BRAKE SYSTEM (ABS)
If only rear wheels are rotated using jacks or
drum tester, the system will diagnose a speed
sensor
malfunction and the "ABS" warning
light will illuminate. But actually no trouble
exists. After inspection stop the engine once
and re-start it,
then make sure that the "ABS"
warning light does not illuminate.
If the battery has been discharged
The engine may stall if the battery has been
completely discharged and the engine is started via
a
jumper cable. This is because the Antilock Brake
System (ABS) requires a
large quantity of
electricity. In this case, wait until the battery is
recharged,
or set the ABS to a non-operative state
by removing the fuse for the ABS (40A). After the
battery has been recharged, stop the engine and
install the ABS fuse. Start the engine again, and
confirm that the ABS warning light does not light.
NOTE ON INTERMITTENTS
As with virtually any electronic system, it is difficult
to identify an intermittent failure. In such a case
duplicating the system malfunction during a test
drive
or a good description of vehicle behavior from
the customer may be helpful in locating a "most
likely" failed component or circuit. The symptom
diagnosis chart may also be useful in isolating the
failure. Most intermittent problems are caused by
faulty electrical connections or wiring. When an
intermittent failure is encountered, check suspect
circuits for:
Suspected harness damage.
• Poor mating of connector halves or terminals
not fully seated in the connector body (backed
out).
Improperly formed or damaged terminals.
TEST DRIVING ABS COMPLAINT
VEHICLES
In case that there has been an abnormality in the
lighting pattern of "ABS" warning light, the fault
can be located in accordance with the "DIAGNOSIS
BY 'ABS' WARNING LIGHT ILLUMINATION
PATTERN". In case of such trouble as can be
detected
by the driver as a vehicle symptom,
however, it is necessary to give a test drive
following the test procedure mentioned below,
thereby reproducing the symptom for trouble
diagnosis on a symptom basis:
1. Start the engine and make sure that the "ABS"
W/L goes OFF. If the W/L remains ON, it
means that the Diagnostic Trouble Code (DTC)
is stored. Therefore, read the code and
locate
the fault.
2. Start the vehicle and accelerate to 30 km/h (19
mph) or more.
3. Slowly brake and stop the vehicle completely.
4. Then restart the vehicle and accelerate to 40
km/h (25 mph) or more.
5. Brake at a time so as to actuate the ABS and ... ~
stop the vehicle.
6. Be cautious of abnormality during the test. If
theW/Lis actuated while driving, read the DTC
and locate the fault.
7. If the abnormality is not reproduced by the
test, make best efforts
to reproduce the
situation reported
by the customer.
8. If the abnormality has been detected, repair in
accordance
with the "SYMPTOM DIAGNOSIS".
NOTE:
Be sure to give a test drive on a wide, even
road
with a small traffic.
If an abnormality is detected, be sure to
suspend the test and start
trouble diagnosis at
once.
II ABS" WARNING LIGHT
When ABS trouble occurs to actuate "ABS"
warning light, the trouble code corresponding to
the trouble is stored in the EBCM. Only ordinary
brake is available with ABS being unactuated. Even
when "ABS" warning light is actuated, if the starter
switch is set
ON after setting it OFF once, the EBCM
checks
up on the entire system and, if there is no
abnormality, judges ABS to work currently and the
warning light is lit normally even though the
trouble code is stored.
NOTE:
Illumination of the "ABS" warning light
indicates that antilock braking is no longer
available. Power assisted braking without
antilock control is still available.
NORMAL OPERATION
II ABS" WARNING LIGHT
When the ignition is first moved from "OFF" to
"RUN", the amber "ABS" warning light will turn
"ON". The "ABS" warning 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. The
warning light should remain "OFF" at all other
times.
•

4-WHEEL ANTILOCK BRAKE SYSTEM (ABS) 5A4-7
BASIC DIAGNOSTIC FLOW CHART
I CUSTOMER COMPLAINT I
I
' I QUESTIONING TO CUSTOMER 1
I
BASIC INSPECTION I REFER TO "BASIC INSPECTION PROCEDURE"
+
I
I TECH 1 AVAILABLE I
I TECH 1 UNAVAILABLE REFER TO "DIAGNOSIS BY 'ABS'
t
WARNING LIGHT ILLUMINATION
PATTERN"
I MAKE SURE OF DTC BY I MODE F2: TROUBLE CODE I CHECK IF THE DTC IS STORED OR NOT
I I
I DTC I I NO DTC I I NO
DTC I
I DTC I
I I
I TEST
DRIVEl
I
I W/L NOT LIT I I W/L IS LIT I
I
I TROUBLE DIAGNOSIS I BASED ON SYMPTOM I LOCATING THE FAUL Tj BYDTC
REFER TO "SYMPTOM
DIAGNOSIS"
I REPAIR OF FAUL TV PART I
I
CHECK TRANSMISSION/TRANSFER~ INPUT (CHART C-3, C-4, TC-3, TC-4)
ELIMINATION
OF DTC I
I
INSPECTION OF "ABS" W/L ILLUMINATION
1 PATTERN WITH IGNITION SW "ON"
+ I TEST DRIVE ~ REPEAT THE DIAGNOSIS IF
THE SYMPTOM OR DTC
APPEARS AGAIN
I FINISHED I
DTC = Diagnostic Trouble Code

ABS-2E
NO TROUBLE CODE
SELECT MODE
FO:DATA LIST
F1: NOT USED
F2:TROUBLE CODE
SELECT MODE
F3:SNAP SHOT
F4:CLEAR CODE
F5:ACTUATOR TEST
SELECT MODE
F6:WHEEL SENSORS
*note 1
ABS-2E
NO DATA!
CHECK ALDL CONN.
SEE CHART 1
4-WHEEL ANTILOCK BRAKE SYSTEM (ABS) 5A4-13
There is no trouble code in ABS system.
(In case of trouble, trouble code is displayed)
Select
desired mode (see following explanation of modes). (Scroll up and
down by key III. m operation.)
Chances are
that the picture as shown in the box appears next to the 8th
picture.
It is displayed when there is no communication between TECH 1
and the EBCM. The
following causes are considered:
CHART
1:
There are three different situations in which EBCM does not communicate
with TECH 1:
1) Disconnection of Data Link Connector (ALDL) Harness
Check
to see "ABS" warning light is normally actuated with IGN being
ON. lfthe light is not actuated, harness abnormality is suspected.
2) While driving (wheel speed values inputted)
No problem in running the vehicle after communicating with TECH 1
while the vehicle stops.

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.

5A4-30 4-WHEEL ANTILOCK BRAKE SYSTEM (ABS)
@: ABS
warning light test
In this test, light is actuated to make sure of its function (Fig. 5A4-10).
Fig. 5A4-10
TECH 1 Display
Key Operation
Is the light blinking ? ABS W/L * BLINK If so, press the YES key. If not, press the NO key.
OKAY ?
(YES/NO)
If
fault exists and the NO key is pressed
A test failure.
TEST FAILED Check ABS W/L wiring and
fuses.
(YES)
i _______________________________________________________________________ \
! •

5A4-38 4-WHEEL ANTI LOCK BRAKE SYSTEM (ABS)
SYMPTOM DIAGNOSIS
The symptoms that cannot be indicated by warning light can be divided in the following five categories:
1) ABS works frequently but vehicle does not decelerate.
2) Uneven braking occurs while ABS works.
3) The wheels lock during braking.
4) Brake pedal feel is abnormal.
5) Braking sound (from hydraulic unit) is heard while not braking.
These are
all attributable to problems which cannot be detected by EBCM's self-diagnosis. Use the
customer complaint and a test to determine which symptom is present. Then follow the appropriate flow
chart listed below.
Diagnostic Flow Charts
No. Symptom Without TECH 1 With TECH 1
1
ABS works frequently but vehicles does not Chart A-1 Chart TA-1
decelerate.
2
Uneven braking occurs while ABS works. Chart A-2 Chart
TA-2
3 The
wheels are locked. Chart A-3 Chart
TA-3
4 Brake
pedal feel is abnormal. Chart A-4 -
5 Braking
sound (from hydraulic unit) is heard while Chart A-5 Chart
TA-5 not braking.
•

5A4-46 4-WHEEL ANTILOCK BRAKE SYSTEM (ABS)
DIAGNOSIS BY II ABS,
WARNING LIGHT ILLUMINATION PATTERN
In the event that there is abnormality in the "ASS" warning light illumination pattern while the key is in the ON
position or if the warning light is actuated during driving, trouble should be diagnosed on a illumination pattern
basis as
follows:
No.
Condition "ABS" Warning Diagnostic Chart
Light Illumination Pattern
1 Warning light is ON Normal Warning I I actuated normally light OFF ' , Still not lit during
Starter ON : driving
sw OFF
2 Warning light is
Warning ON Warning light lighting
not lit light OFF circuit trouble
ON .... to CHART 8-1
Starter I sw OFF
3 Warning light blinks Warning ON Warning light lighting
twice light OFF circuit trouble
:
ON ... to CHART
B-2
Starter
sw OFF
4 Warning light ON Diagnostic trouble codes Warning J remains ON light OFF are
stored.
Display diagnostic trouble ' codes and diagnose on a
Starter
ON I code basis according to
sw OFF the flow charts.
5 Warning light is ON~ Warning actuated while light OFF driving During driving
ONr(l Starter
sw OFF

4-WHEEL ANTILOCK BRAKE SYSTEM (ASS) 5A4-47
DIAGNOSTIC TROUBLE CODES (DTCs)
When the warning light in the meter remains ON, the EBCM stores the fault identification and disables the
.........,.. ABS.
1. How to display and erase DTCs:
NOTE:
• If DTCs are not displayed, harness BB 14 may be disconnected. Repair the harness and try DTC
display again.
• DTCs can be displayed also by TECH 1. For further details, see "MODE F2: TROUBLE CODE" in this
section.
(1)
How to start DTC display:
• Confirm
that the vehicle has come to a complete stop (with the wheels standing still) and that the
brake pedal is not depressed. (Unless these two condition are satisfied, DTC display cannot be
started.)
• With IGN OFF, connect #1 terminal with #3 terminal (GND) (Fig. 5A4-14). Then turn IGN ON.
The DLC is located behind the driver side kick panel.
1 2 3
Jumper Wire Data link Connector (Orange}
Fig. 5A4-14
• Keep #1 terminal connected with #3 terminal (GND) during DTC display.
(If
#1 terminal is separated from #3 terminal (GND) during display, display will stop.)
(2) DTC display:
•
DTC is displayed by blinking warning light.
•
Double-digit display
•
First, normal DTC 12 is displayed three times and then any other DTCs are displayed three times. (If
no other DTCs have been stored, the display of DTC 12 will be repeated.)
(3) How to erase code:
• Connect and disconnect jumper wire between #1 terminal and #3 terminal (GND) at least 3 times
within 30 seconds.
• There is no time limit to "opening", but "each grounding" must be more than 1 second and the
entire 3-grounding sequence must be completed within 30 seconds.
ABS W/L
#1 terminal
r---------------, ------ON
More than 1 sec.
OFF
.--------, ------ GND
OPEN
' ,._ _________ ,_:
Within 30 sec.