display ISUZU TROOPER 1995 Owner's Manual

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.

5A4-48 4-WHEEL ANTILOCK BRAKE SYSTEM (ABS)
(4) Notes
• If the following should occurs during Diagnostic Trouble Code (DTC) display the display will be
discontinued.
After initial check, the status that is under the control of ABS will be returned:
- The vehicle starts (The wheels turn)
or the brake pedal is depressed.
• Up to 3 different codes can be stored.
• If the ABS should turn OFF due to an intermittent defect, the system will be restored at the next key
cycle,
if the initial check finds no abnormality (when IGN is switched from OFF to ON).
(5) An example of DTC display
3.2 0.4 0.4 :.,..___......: .......... ~: I I I I
W/L ON: I I t
OFF'
Self-diagnosis starts

1.2 0.4 0.4 ~:+-+:---__.,..: I I I I I I I I
(Unit: sec.) 3.2 ~: ' ' ' '

After displaying
DTC 12 three times, one DTC after another is displayed, starting with the most recent one.
(However, display is discontinued after about 5 minutes.)

-B-0-----·
The DTC 12 is displayed repeatedly.
(display is discontinued after about 5 minutes after)
•

5A4-52 4-WHEEL ANTILOCK BRAKE SYSTEM (ABS)
CHART B-3 ~I
EBCM ABNORMALITY (DIAGNOSTIC TROUBLE CODE 14)
• TURN THE KEY OFF, CONNECT THE PINOUT BOX. AND INSPECT EBCM GROUND
• MEASURE RESISTANCE BETWEEN THE TERMINALS
10, 20 AND 34, AND BODY GROUND
T
~ $
• TURN THE KEY OFF, CONNECT THE EBCM
• ERASE THE DTC I REPAIR THE BODY GROUND HARNESS I
• TURN IGNITION ON, TO PERFORM SYSTEM
SELF-CHECK
IF WARNING LIGHT REMAINS ON, DISPLAY DTCS
ONCE AGAIN
I
r I CODE14 I I OTHER THAN
14 I
I I
REPLACE EBCM I !INSPECT IN ACCORDANCE WITH I THE DTC DISPLAYED
DTC = Diagnostic Trouble Code
•

CHART B-13, TB-13 l)EeR:[I I TECH 1 I
SENSOR SIGNAL INPUT ABNORMALITY (DIAGNOSTIC TROUBLE CODE 65)
SELECT F3: SNAP SHOT MANUAL TRIGGER
WITH
WHEEL SPEED DATA DISPLAYED, RUN THE *1 VEHICLE WHEN SPEED HAS ARRIVED AT 30 KM/H
(18 MPH), PRESS F9 KEY
CHECK SPEED DATA ON EACH WHEEL (REFER TO THE CRITERIAL GIVEN BELOW)
ONLY THE ABNORMAL WHEEL SHOULD
FOLLOW THE NEXT FLOWCHART
IS THERE PLAY IN SENSOR/SENSOR ROTOR? -I)Eel{[l ALL THE WHEELS SHOULD FOLLOW THE FOLLOWING FLOWCHART
IS THERE POWDERED IRON STICKING
TO SENSOR/SENSOR ROTOR?
cill
~
Sensor Signal Abnormality Criteria using TECH 1 --------,
1) While driving, the speed of one or two wheels is 25% or more higher than that of
the other wheels.
2) The speed of one or two wheels is 10 km/h (6 mph) or more higher than that of the
other
wheels.
3) During steady driving, wheel speed changes abruptly.
* 1 The vehicle must run on a level paved road.

5A4-72 4-WHEEL ANTILOCK BRAKE SYSTEM (ABS)
CHARTTC-4 I TECH 1 I
TRANSMISSION INPUT INSPECTION PROCEDURE
I CONNECT TECH , I
I
I SELECT MODE FO: DATA LIST I
MIT J AfT
I I
SHIFT POSITION
DISPLAY SHIFT POSITION DISPLAY
1,
2, R OFF-ROAD INPUT CLOSED L, R OFF-ROAD
INPUT CLOSED
3, 4, 5, N
OFF-ROAD INPUT OPEN OTHER THAN ABOVE OFF-ROAD
INPUT OPEN
SHIFT GEAR AND MAKE SURE OF THE ABOVE OPERATE THE LEVER AND MAKE SURE OF THE ABOVE
I I
ciJ $ $ ciJ
ABNORMAL T/M SW, INHIBITOR SW, OR HARNESS
• REPAIR T/M SW, INHIBITOR SW, OR HARNESS
•

......, .., LU
READING DIAGNOSTIC TROUBLE CODES
(Fig. 6E2-1)
The provision for communicating with the Engine
Control Module (ECM) is the Data Link Connector
(DLC) (See Fig. 6E2-1 ). The DLC is located behind
the
lower front instrument panel. It is used in the
assembly plant
to receive information in checking
that the engine is operating properly before it
leaves the plant. The diagnostic trouble code(s)
(DTCs) stored in the ECM's memory can be read
either through a hand-held diagnostic scannner
plugged into the
DLC or by counting the number
of flashes of the "Check Engine" Malfunction
Indicator Lamp (MIL) when the diagnostic test
terminal
ofthe DLC is grounded. The DLC terminal
"1" (diagnostic request) is pulled "Low"
(grounded) by jumpering to DLC terminal "3",
which is a ground wire. This will signal the ECM
that you want to "flash" DTC(s), if any are present.
Once terminals "1" and "3" have been connected,
the ignition switch
must be moved to the "ON"
position, with the engine not running. At this
point, the
"Check Engine" MIL should flash DTC 12
three times consecutively. This
would be the
following flash, sequence: "flash, pause, flash­
flash,
long pause, flash, pause, flash-flash, long
pause, flash, pause, flash-flash". DTC 12 indicates
that the ECM's diagnostic system is operating.
If
DTC 12 is not indicated, a problem is present
within the diagnostic system itself, and should be
addressed
by consulting the appropriate
diagnostic chart in
DRIVEABILITY AND
EMISSIONS (SECTION 6E2-A).
Following the output of DTC 12, the "Check
Engine" MIL
will indicate a DTC three times if a
DTC is present, or it will simply continue to output
DTC 12. If more than one DTC has been stored in
the
ECM's memory, the DTC(s) will be outputfrom
the lowest to the highest, with each DTC being
displayed three times.
--
Eig tU!2-1-...
DRIVEABILITY AND EMISSIONS 6E2-5
CLEARING TROUBLE CODES
When the ECM sets a trouble code, the "Check
Engine" MIL
will come "ON" and a trouble code
will be stored in memory. If the problem is
intermittent, the light
will go out after 10 seconds,
when the fault goes away. However, the trouble
code
will stay in the ECM memory until the battery
positive voltage
to the ECM is removed.
Removing battery positive voltage
for 30 seconds
will clear all stored trouble codes.
Trouble
Codes should be cleared after repairs
have been completed. Also, some Diagnostic
Charts will tell you to clear the DTC(s) before using
the chart. This
allows the ECM tosetthe DTCwhile
going through the chart, which will help to find the
cause
of the problem more quickly.
wcAUTION:
• To prevent ECM damage, the key must be "OFF"
when disconnecting or reconnecting power to
ECM (for example battery cable, ECM pigtail, ECM
fuse, jumper cables, etc.)
When using a hand-held diagnostic scanner,
or
"Scan tool" to read the DTC(s), clearing the DTC(s)
is done in the same manner as in the above
procedure.
DIAGNOSTIC TEST MODE
When the diagnostic test terminal is grounded
with the ignition "ON" and the engine "OFF", the
system
will enter what is called the Diagnostic
Test Mode.
In this diagnostic test mode the ECM
will:
1. Flash the "Check Engine" MIL "ON" and
"OFF" rapidly (indicating the system is
operating correctly).
2. Display any stored trouble codes by flashing
the
"Check Engine" MIL. Each DTC will be
flashed three times, then
DTC 12 will be
flashed again.
3. Energize all ECM controlled relays and
solenoids except
fuel pump relay. This
allows checking circuits which may be
difficult to energize without driving the
vehicle and being under particular operating
conditions.
4. The idle air control valve moves to its fully
extended position on most models, blocking
the
idle air passage. This is useful in checking
the
minimum idle speed.

SECTION II A"
DIAGNOSTIC PROCEDURE SUMMARY
•IGNITION "ON", ENGINE STOPPED. •IS THE MALFUNCTION INDICATOR LAMP "ON"?
•
JUMPER DATA LINK CONNECTOR TERM. 1 TO 3. • DOES MALFUNCTION INDICATOR LAMP FLASH DIAGNOSTIC TROUBLE CODE (DTC) 12?
REFER TO APPLICABLE DTC CHART, START WITH LOWEST DTC.
"SCAN TOOL" SERIAL DATA. REPAIR AS NECESSARY. IF ALL OK, SEE DRIVEABILITY SYMPTOMS IN SECTION B.
Fig. 6E2-2
r
DRIVEABILITY AND EMISSIONS 6E2-13
This is the starting point for the diagnostic procedures.
The diagnostic charts are
related to the Engine Control
Module
(ECM) and will determine if the ECM is working
properly.
This section diagnoses the fuel system controlled by
the
ECM and has charts to diagnosis a circuit when the
ECM has displayed a trouble code.
The
way to approach a problem is to follow some basic
steps.
1.
Are the On-Vehicle Diagnostics working?
We find this out by performing the "On-Board
Diagnostic System Check" Since this is the
starting point
for the diagnostic procedure,
always
begin here.
If the On-Vehicle Diagnostics aren't working, the "On­
Board Diagnostic System Check" will lead you to a
chart in Section
"A" to correct the problem. If the On­
Vehicle
Diagnostics are OK, the next step is:
2.
Is there a Trouble Code stored?
If a trouble code is stored, go directly to the
numbered
DTC chart in Section "A". This will
determine if the fault is still present. If no trouble
code is stored, the third step is:
3. "Scan Tool" Serial Data.
This
involves reading the various pieces of
information available on the Serial Data Stream
with one of the tools available for that purpose.
Information on these tools and the meaning of the
various
displays can be found in the following
paragraphs. Expected readings can be found on
the facing page
for the On-Board Diagnostic
System Check.
This procedure, which takes
only a short time, will help
lead
you to repair the problem in the least amount of
time.

6E2-14 DRIVEABILITY AND EMISSIONS
DATA LINK CONNECTOR ''SCAN TOOLS''
The Engine Control Module (ECM) can communicate a
variety
of information through data link connector
terminal
"2". This data is transmitted at a high frequecy
which requires a
"Scan tool" for interpretation. There
are several
"Scan tools" available for reading this
information.
With an understanding
of the data which the tool
displays, and knowledge of the circuits involved, the
tool can be
very useful in obtaining information which
would be more difficult or impossible to obtain with
other equipment.
"Scan tools" do not make the use of diagnostic charts
unnecessary, nor
can they indicate exactly where a
problem is in a particular circuit. Trouble Tree
Charts
incorporate diagnosis procedures using a "Scan tool"
where possible and most charts require the use of a
"Scan tool" when it is applicable.
A "SCAN TOOL" THAT DISPLAYS FAUL TV
DATA SHOULD NOT BE USED AND THE
PROBLEM SHOULD BE REPORTED TO THE
MANUFACTURER. THE USE OF A FAUL TV
"SCAN TOOL" CAN RESULT IN MIS­
DIAGNOSIS
AND UNNECESSARY PARTS
REPLACEMENT.
ECM's have two (2) modes for transmitting
information. The
following information will describe
the system operation in each
of the modes.
Data List (FO)
On engines that can be monitored in the "Open"
mode, certain parameters can be observed
without changing the engine operating
characteristics. The parameters capable
of being
read vary with engine families.
Most "Scan tools"
are programmed so that the system will go
directly into the data link connector mode
if the
"Open" mode is not available.
''SCAN TOOL'' LIMITATIONS AND USE
The "Scan tool" allows a quick check of sensors
and switches which are inputs
to the ECM. The
"Scan tool" allows one to manipulate wiring
harnesses or components under the hood while
observing the "Scan Tool" readout. This helps in
locating intermittents
with the engine not
running.
INTERMITTENT CONDITIONS
The "Scan tool" is helpful in cases of intermittent
operation. The
tool can be plugged in and
observed while driving the vehicle under the
condition
where the light comes "ON" momen- tarily,
or the
engine driveability is poor
momentarily.
If the problem seems to be related
to certain areas
that can be checked on the "Scan ~
tool", then those are the positions that should be
checked while driving the vehicle. If there does
not seem to
be any correlation between the
problem and any specific circuit, the
"Scan tool"
can be checked on each position, watching for a
period
of time to see if there is any change in the
readings that indicates intermittent operation.
The
"Scan tool" is also a useful and quick way of
comparing operating parameters of a poorly
operating engine with a known good one. For
example; A sensor may shift in
value but not set a
diagnostic trouble code. Comparing with a known
good vehicle may uncover the problem.
The
"Scan tool" has the ability to save time in
diagnosis and prevent the replacement
of good
parts. The key to using the
"Scan tool" success­
fully
for diagnosis lies in the technicians ability to
understand the system he is trying to diagnose as
well as an understanding of the "Scan tool's"
limitations. Therefore, the technician should read
the tool operating manual to become familiar
with
the tool. The following information will describe
most of the "Scan tool" positions and how they
can be helpful in diagnosis.
"SCAN TOOL" POSITIONS
INJECTOR PULSE WIDTH
In this position, the reading is given in milli­
seconds which is the on time that the ECM is
commanding to the injector(s).
CLOSED LOOP/OPEN LOOP
This position will indicate whether the engine
control system
is operating in open or closed
loop. Most systems go closed loop after a certain
amount of run time, when engine coolant
temperature
is high enough, and the oxygen
sensor becomes active.
TROUBLE CODES
Will display any trouble codes stored in the ECM
memory.
THROTTLE POSITION (TP) SENSOR
Values read will be the voltage as seen by the ~
ECM. The voltage should be the TP sensor
specification
with the throttle closed and go up to
about 5 volts with
wide open throttle.
•

THROTTLE ANGLE
Displays in percent the amount the throttle is
open.
HEATED OXYGEN SENSOR (H02S)
The reading will be read out in millivolts (mv) with
a range from 1 to 999 mv. If the reading is
consistently
below 350 (350 mv), the fuel system
is running
lean as seen by the Engine Control
Module
(ECM) and if the reading is consistently
above
550 (550 mv), the system is running rich.
VEHICLE SPEED SENSOR (VSS)
Displays vehicle speed, useful in checking
speedometer accuracy.
PROGRAMMABLE READ ONLY MEMORY
(PROM)
ID
In this position the last4 digits of the Mem-Cal part
number will be displayed.
REVOLUTION PER MINUTE (RPM)
Displays engine speed. Often useful if extra
reference pulses are suspected. A sudden high
revolution per minute indication while at a steady
throttle
would indicate electrical interference
(EMI) in the reference circuit. This interference is
usually caused by ECM wires too close to ignition
secondary wires
or an open electronic ignition
ground circuit.
MILE PER HOUR (MPH)
Displays vehicle speed. Useful in checking
speedometer accuracy.
ENGINE COOLANT TEMPERATURE (ECT)
Displays engine temperature in degress centi­
grade.
After engine is started the temperature
should rise steadily to about
85-95·c, then
stabilize
when the thermostat opens.
INTAKE AIR TEMPERATURE (IAT)
SENSOR
Displays temperature of the intake manifold air.
Should read close to ambient air temperature
when the engine is cold, and rise
as underhood
and engine temperature increases.
DRIVEABILITY AND EMISSIONS 6E2-15
MANIFOLD ABSOLUTE PRESSURE (MAP)
The Manifold Absolute Pressure (MAP) Sensor
produces a low signal voltage when MAP is low
(high vacuum) and a high voltage when the
pressure is high (low vacuum).
With the ignition on and the engine stopped, the
manifold absolute pressure is equal
to
atmospheric pressure and the signal voltage will
be high. This information is used by the ECM as an
indication of vehicle altitude and is referred to as
barometric pressure. Comparison of this
barometric pressure reading
with a known good
vehicle
with the same sensor is a good way to
check accuracy
of a "suspect" sensor. Readings
should be the same
±0.4 Volt.
MAP
Sensors have a colored plastic insert visible
in the connector cavity.
Sensors with the same
insert color are identical in calibration. The
harness electrical connector color should also be
the same
as the sensor insert color.
BAROMETRIC PRESSURE (BARO)
Displays the MAP reading before the engine was
started. This value
will vary depending on
Barometric Pressure and altitude.
EXHAUST GAS RECIRCULATION (EGR)
(ON/OFF)
The exhaust gas recirculation system uses a valve
controlled by vacuum to feed a small amount of
exhaust gas back into the intake manifold to
control formation
of NOx. Like all ECM outputs the
"Scan tool" only indicates that the ECM has
commanded the function and does
not indicate
that the function has
really happened.
SHORT TERM (S.T.) FUEL TRIM AND LONG
TERM (L.T.) FUEL TRIM
On Fuel Injected Engines, normal readings for
these positions are around 128. If higher, it
indicates that the ECM is adding fuel to the base
fuel calculation because the system is lean.
If the
numbers are below 128, the
ECM is taking out fuel
from the base calculation because the system is
rich. The
S.T. Fuel Trim is short term corrective
action while the
L.T. Fuel Trim portion (which is a
long term correction)
will only change if the
intergrator has seen a condition which lasts
for a
calibrated period
of time.

6E2-16 DRIVEABILITV AND EMISSIONS
LONG TERM (LT.) FUEL TRIM
There are from zero to seventeen different cells
which the Engine Control Module (ECM) learns at
depending on revolution per minute (rpm) and
manifold absolute pressure. This parameter
will
display what cell the ECM is using for the fuel
calculation at the time.
IDLE AIR CONTROL (lAC) COUNTS
This system is used to control engine idle speed to
the desired rpm, for different operating
conditions.
In this diagnostic test mode, the
numbers
will indicate what position the ECM
thinks the valve is in. The ECM moves the idle air
control in counts and these counts are displayed
on a
"Scan tool".
DESIRED REVOLUTION PER MINUTE
Indicates the rpm to which the ECM is trying to
control the idle.
AIR CONDITIONING (A/C) REQUEST
Displays the state of the Air Conditioning (A/C)
signal line to the ECM. Should read "YES"
whenever the A/C is requested.
AIR CONDITIONING {A/C) CLUTCH
Displays "ON" when the ECM has commanded
the
A/C Clutch "ON".
POWER STEERING PRESSURE (PSP)
SWITCH
Displays the state of switch. This reading may
vary
with the tool used and the type of switch
installed on the vehicle. The important thing is
that the reading changes state (switches) when
the steering is moved against the stops.
BA TTERV POSITIVE VOLTAGE
Displays the battery positive voltage detected at
the
ECM ignition input.
SPARK ADVANCE
This is a amount of total spark advance including
the base electronic ignition timing.
START UP ENGINE COOLANT
This parameter is the engine coolant temperature
at the
time the engine was started.
ENGINE SPEED (RPM)
RPM calculated during a crank mode, helpful in
diagnosing a NON-start condition.
FUEL TRIM ENABLE
This value is an indication when the Fuel Trim
Enable values are being updated within the ECM
program.
AIR/FUEL RATIO
This is the air to fuel ratio that is being
commanded to the injectors.
INDUCTION AIR CONTROL
The "Scan tool" will display the command being
given to the induction air control
plate system
solenoid.
SECTION B-DRIVEABILITY SYMPTOMS
Always start with Section "A" "On-Board Diagnostic
System Check" before proceeding to the driveability
symptoms.
Section "A" checks the ECM which may
cause the driveability problem. A definition
of each
symptom is included. This will then lead to the most
probable causes of the driveability problem.
SECTION C-COMPONENTS SYSTEMS
There are many component systems that are used to
control fuel and emissions. Section "C" introduces
each component system or control
with a general
description, diagnosis, and on-vehicle service.
Each
of the Section "C" diagnosis sections will contain
information on
how the "Scan tool" can be used for
diagnosing a particular component when a trouble
code has
not been set. (example: Section "C1" under
diagnosis
will explain how the "Scan tool" can be used
for diagnosis as well as what the normal readings
would be for the ECM Sensors.
•