1998 ISUZU TROOPER Ecm

6E±26
4JX1±TC ENGINE DRIVEABILITY AND EMISSIONS
Output Components:
Output components are diagnosed for proper response to
control module commands. Components where
functional monitoring is not feasible will be monitored for
circuit continuity and out-of-range values if applicable.
Output components to be monitored include, but are not
limited to, the following circuit:

EGR VSV

EGR EVRV

Electronic Transmission controls

Injector

Intake throttle

Glow plug

MIL control
Refer to ECM and Sensors in General Descriptions.
Passive and Active Diagnostic Tests
A passive test is a diagnostic test which simply monitors a
vehicle system or component. Conversely, an active test,
actually takes some sort of action when performing
diagnostic functions, often in response to a failed passive
test.
Intrusive Diagnostic Tests
This is any on-board test run by the Diagnostic
Management System which may have an effect on
vehicle performance or emission levels.
Warm-Up Cycle
A warm-up cycle means that engine at temperature must
reach a minimum of 70
C (160
F)
and rise at least 22
C
(40
F) over the course of a trip.
Freeze Frame
Freeze Frame is an element of the Diagnostic
Management System which stores various vehicle
information at the moment an emissions-related fault is
stored in memory and when the MIL is commanded on.
These data can help to identify the cause of a fault. Refer
to
Storing And Erasing Freeze Fame Data for more
detailed information.
Failure Records
Failure Records data is an enhancement of the OBD
Freeze Frame feature. Failure Records store the same
vehicle information as does Freeze Frame, but it will store
that information for any fault which is stored in on-board
memory, while Freeze Frame stores information only for
emission-related faults that command the MIL on.
Common OBD Terms
Diagnostic
When used as a noun, the word diagnostic refers to any
on-board test run by the vehicle's Diagnostic
Management System. A diagnostic is simply a test run on
a system or component to determine if the system or
component is operating according to specification. There
are many diagnostics, shown in the following list:

EGR

engine speed

vehicle speed

ECT
MAP

VSV

IAT

ITP

AP

FT (Fuel Temp)

RP (Rail Pressure)

OT (Oil Temp)

EGR EVRV

Idle SW

Brake SW
The Diagnostic Executive
The Diagnostic Executive is a unique segment of
software which is designed to coordinate and prioritize
the diagnostic procedures as well as define the protocol
for recording and displaying their results. The main
responsibilities of the Diagnostic Executive are listed as
follows:

Commanding the MIL (ªCheck Engineº lamp) on and
off

DTC logging and clearing

Freeze Frame data for the first emission related DTC
recorded

Current status information on each diagnostic
Diagnostic Information
The diagnostic charts and functional checks are designed
to locate a faulty circuit or component through a process
of logical decisions. The charts are prepared with the
requirement that the vehicle functioned correctly at the
time of assembly and that there are not multiple faults
present.
There is a continuous self-diagnosis on certain control
functions. This diagnostic capability is complemented by
the diagnostic procedures contained in this manual. The
language of communicating the source of the malfunction
is a system of diagnostic trouble codes. When a
malfunction is detected by the control module, a
diagnostic trouble code is set and the Malfunction
Indicator Lamp (MIL) (ªCheck Engineº lamp) is
illuminated.
Malfunction Indicator Lamp (MIL)
The Malfunction Indicator Lamp (MIL) looks the same as
the MIL you are already familiar with ªCheck Engineº
lamp.
Basically, the MIL is turned on when the ECM detects a
DTC that will impact the vehicle emissions.

When the MIL remains ªONº while the engine is
running, or when a malfunction is suspected due to a
driveability or emissions problem, a Powertrain
On-Board Diagnostic (OBD) System Check must be
performed. The procedures for these checks are
given in On-Board Diagnostic (OBD) System Check.
These checks will expose faults which may not be
detected if other diagnostics are performed first.
DTC Types
Characteristic of Code

6E±27 4JX1±TC ENGINE DRIVEABILITY AND EMISSIONS

Non-Emissions related

Dose not request illumination of any lamp

Stores a History DTC on the
first trip with a fail

Stores Fail Record when test fails

Updates the Fail Record each time the diagnostic test
fails
Storing and Erasing Freeze Frame Data and Failure
Records
The data captured is called Freeze Frame data. The
Freeze Frame data is very similar to a single record of
operating conditions. Whenever the MIL is illuminated,
the corresponding record of operating conditions is
recorded to the Freeze Frame buffer.
Data from these faults take precedence over data
associated with any other fault. The Freeze Frame data
will not be erased unless the associated history DTC is
cleared.
Each time a diagnostic test reports a failure, the current
engine operating conditions are recorded in the
Failure
Records
buffer. A subsequent failure will update the
recorded operating conditions. The following operating
conditions for the diagnostic test which failed
typically
include the following parameters:

Engine Speed

Engine Load

Engine Coolant Temperature

Vehicle Speed

Intake Throttle Position

MAP

Injector Base Pulse Width

Loop Status
Data Link Connector (DLC)
The provision for communication with the contorl module
is the Data Link Connector (DLC). It is located at behind
the lower front instrument panel. The DLC is used to
connect to a Tech 2. Some common uses of the Tech 2
are listed below:

Identifying stored Diagnostic Trouble Codes (DTCs).

Clearing DTCs.

Performing out put control tests.

Reading serial data.
060RW046
Verifying Vehicle Repair
Verification of vehicle repair will be more comprehensive
for vehicles with OBD system diagnostic. Following a
repair, the technician should perform the following steps:
1. Review and record the Fail Records and/or Freeze
Frame data for the DTC which has been diagnosed.
2. Clear DTC(s).
3. Operate the vehicle within conditions noted in the Fail
Records and/or Freeze Frame data.
4. Monitor the DTC status information for the specific
DTC which has been diagnosed until the diagnostic
test associated with that DTC runs.
Following these steps are very important in verifying
repairs on OBD systems. Failure to follow these steps
could result in unnecessary repairs.
Reading Flash Diagnostic Trouble Codes
The provision for communicating with the Engine Control
Module (ECM) is the Data Link Connector (DLC). The
DLC is located in the front console box. 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 scanner plugged into the DLC or by counting
the number of flashes of the ªCheck Engineº Malfunction
Indicator Lamp (MIL) when the diagnostic test terminal of
the DLC is grounded. The DLC terminal ª6º (diagnostic
request) is pulled ªLowº (grounded) by jumpering to DLC
terminal ª4º, which is a ground wire.
This will signal the ECM that you want to ªflashº DTC(s), if
any are present. Once terminals ª4º and ª6º have been
connected, the ignition switch must be moved to the ªONº
position, with the engine not running.
The ªCheck EngineºMIL will indicate a DTC three times if
a DTC is present. If more than one DTC has been stored

6E±28
4JX1±TC ENGINE DRIVEABILITY AND EMISSIONS
in the ECM's memory, the DTC(s) will be output from the
lowest to the highest, with each DTC being displayed
three times.
The DTC display will continue as long as the DLC is
shorted.
Reading Diagnostic Trouble Codes Using
a TECH 2
The procedure for reading diagnostic trouble code(s) is to
used a diagnostic Tech 2. When reading DTC(s), follow
instructions supplied by Tech 2 manufacturer.
For the 1998 model year, Isuzu dealer service
departments will continue to use Tech 2.
Clearing Diagnostic Trouble Codes
IMPORTANT:Do not clear DTCs unless directed to do
so by the service information provided for each diagnostic
procedure. When DTCs are cleared, the Freeze Frame
and Failure Record data which may help diagnose an
intermittent fault will also be erased from memory.
If the fault that caused the DTC to be stored into memory
has been corrected, the Diagnostic Executive will begin to
count the ªwarm-upº cycles with no further faults
detected, the DTC will automatically be cleared from the
ECM memory.To clear Diagnostic Trouble Codes (DTCs), use the Tech
2 ªclear DTCsº or ªclear informationº function. When
clearing DTCs follow instructions supplied by the Tech 2
manufacturer.
When a Tech 2 is not available, DTCs can also be cleared
by disconnecting
one of the following sources for at least
thirty (30) seconds.
NOTE: To prevent system damage, the ignition key must
be ªOFFº when disconnecting or reconnecting battery
power.

The power source to the control module. Examples:
fuse, pigtail at battery ECM connectors etc.

The negative battery cable. (Disconnecting the
negative battery cable will result in the loss of other
on-board memory data, such as preset radio tuning).
060RW169

6E±32
4JX1±TC ENGINE DRIVEABILITY AND EMISSIONS
DTC Modes
There are three options available in the Tech 2 DTC mode
to display the enhanced information available. A
description of the new modes, DTC Info, follows. After
selecting DTC, the following menu appears:

DTC Info

Clear Info

Read DTC Info Ordered By Priority
The following is a brief description of each of the sub
menus in DTC Info. The order in which they appear here is
alphabetical and not necessarily the way they will appear
on the Tech 2.
DTC Information Mode
Use the DTC info mode to search for a specific type of
stored DTC information.The service manual may instruct
the technician to test for DTCs in a certain manner.
Always follow published service procedures.
Fail This Ignition
This selection will display all DTCs that have failed during
the present ignition cycle.
History
This selection will display only DTCs that are stored in the
ECM's history memory. It will not display Type B DTCs
that have not requested the MIL (ªCheck Engineº lamp). It
will display all type A and B DTCs that have requested the
MIL and have failed within the last 40 warm-up cycles. In
addition, it will display all type C and type D DTCs that
have failed within the last 40 warm-up cycles.
MIL SVC or Message Requested
This selection will display only DTCs that are requesting
the MIL. Type C and type D DTCs cannot be displayed
using this option. This selection will report type B DTCs
only after the MIL has been requested.
Test Failed Since Code Cleared
This selection will display all active and history DTCs that
have reported a test failure since the last time DTCs were
cleared.
Injector Test
This test is conducted to make it sure that appropriate
electric signals are being sent to injectors Nos. 1 ± 4.
Tech±2 must be used for this test.
Test Procedure:
1. Connect Tech±2 to the vehicle DLC.
2. Set Ignition Switch to the ªONº position.
3. Select Control Test.
4. Select Injector Test.
5. Send instructions to each injector(Switch on), making
sure of injector working noise.
NOTE: If injector working noise (Clink) can hardly be
confirmed, remove the engine head cover noise
insulation.
Refer to Section 6A.6. In the injector whose working noise has been
confirmed, its electric circuit can be regarded as
normal.
As for the injector whose working noise has not been
confirmed, its electric circuit or the injector proper is
faulty.
EGR Valve Test
This test is conducted to check EGR valve for its working.
This test needs Tech±2.
Test Procedure
1. Connect Tech±2 to vehicle DLC.
2. Switch on the engine.
3. Select ªDIAGNOSISº from the main menu.
4. Select Miscellaneous Test.
5. Select EGR Valve.
6. Instruct EGR Valve to check a data list.
7. If change in the data list shows a normal valve, the
working of EGR Valve can be judged to be normal.
Rail Pressure Control Valve Test
This test is conducted to check RPC valve for its working.
This test needs Tech±2.
Test Procedure
1. Connect Tech±2 to vehicle DLC.
2. Switch on the engine.
3. Select ªDIAGNOSISº from the main menu.
4. Select Miscellaneous Test.
5. Select Rail Pressure Control Valve.
6. Instruct RPC Valve to check a data list.
7. If change in the data list shows a normal valve, the
working of RPC Valve can be judged to be normal.
Injector Balance Test
This test is conducted to make it sure that appropriate
electric signals are being sent to injectors Nos. 1-4, when
the engine is idling.
This test needs Tech±2.
Test Procedure
1. Connect Tech±2 to vehicle DLC.
2. The engine is running at idling condition.
3. Select ªDIAGNOSISº from the main menu.
4. Select Miscellaneous Test.
5. Select the injector Balance Test.
6. Send instructions to each injector(Switch On),
making sure change of the engine vibration.
7. In the injector whose change of the vibration has been
confirmed, it's electric circuit can be regarded as
normal.
Data Programming in Case of ECM Change
When replacing ECM, it is necessary to confirm and
record the group sign of injector beforehand. For this
confirmation.

6E±33 4JX1±TC ENGINE DRIVEABILITY AND EMISSIONS
Tech±2 must be used. After ECM change, the recorded
group sign should be programmed. Oil pressure sensor
data also should be programmed.

Group Sign Confirmation Procedure
1 Connect Tech±2 to vehicle DLC.
2 Turn Ignition Switch to the ªONº position.
3 Select ªDIAGNOSISº from the main menu.
4 Select programming.
5 Select Read/store Trim Data.
6 Confirm and record the group sign of injector.

ECM Change

Programming Procedure for Injector Group Sign
1 Connect Tech±2 to vehicle DLC.
2 Turn Ignition Switch to the ªONº position.
3 Select ªDIAGNOSISº from the main menu.
4 Select programming.
5 Select ECM change.
6 Select cylinder.
7 Program Injector Group Sign.
8 Confirm the completion of Injector programming.

Programming Procedure for Oil Pressure Sensor
1 Connect Tech±2 to vehicle DLC.
2 Turn Ignition Switch to the ªONº position.
3 Select ªDIAGNOSISº from the main menu.
4 Select programming.Rail Pressure Sensor Programming
Rail pressure sensor replacement must be programmed.
This programming needs Tech±2.
Programing Procedure
1. Connect Tech±2 to vehicle DLC.
2. Turn Ignition Switch to the ªONº position.
3. Select ªDIAGNOSISº from the main menu.
4. Select Programming.
5. Select Oil Pressure Sensor change.
6. Execute Oil Pressure Sensor Program.
7. Confirm the completion of Oil Pressure Sensor
Program.
Injector Group Sign Programming (Injector
Change)
In case of Injector change, injector group sign must be
programmed.
This programming needs Tech±2.
Programing Procedure
1. Connect Tech±2 to vehicle DLC.
2. Turn Ignition Switch to the ªONº position.
3. Select ªDIAGNOSISº from the main menu.
4. Select Programming.
5. Select Injector change.
6. Select the cylinder changed.
7. Appoint and select Injector Group Sign.
8. Confirm the completion of Injector programming.

6E±34
4JX1±TC ENGINE DRIVEABILITY AND EMISSIONS
Fuel Injection System
060RW178
Legend
(1) ECM
(2) Meter Panel
(3) Battery
(4) Oil Temp Sensor
(5) Rail Pressure Sensor
(6) Glow Relay
(7) Oil Rail
(8) Tech±2
(9) A/C Comp Relay
(10) RPCV
(11) Intake Air Temp Sensor
(12) Engine Coolant Temp Sensor
(13) MAP Sensor
(14) EGR Valve
(15) EGR Pressure Sensor(16) High Pressure Oil Pump
(17) Fuel Pump
(18) VSV
(19) EXH Throttle VSV1
(20) EXH Throttle VSV2
(21) EVRV
(22) Engine Harness Connector
(23) QWS Relay
(24) APS
(25) T.O.D
(26) ECT
(27) OBD
(28) TDC
(29) Injector
(30) Edge Filter

6E±37 4JX1±TC ENGINE DRIVEABILITY AND EMISSIONS
D Group
060RW134
Circuit Description
The on-board diagnostic system check is the starting
point for any driveability complaint diagnosis. Before
using this procedure, perform a careful visual/physical
check of the ECM and engine grounds for cleanliness and
tightness.
The on-board diagnostic system check is an organized
approach to identifying a problem created by an
electronic engine control system malfunction.
Diagnostic Aids
An intermittent may be caused by a poor connection,
rubbed-through wire insulation or a wire broken inside the
insulation. Check for poor connections or a damaged
harness. Inspect the ECM harness and connector for
improper mating, broken locks, improperly formed or
damaged terminals, poor terminal-to-wire connection,
and damaged harness.
Test Description
Number(s) below refer to the step number(s) on the
Diagnostic Chart:
1. The MIL (ªCheck Engineº lamp) should be ªONº
steady with the ignition ªONº/engine ªOFF.º If not,
Chart A-1 should be used to isolate the malfunction.
2. Checks the Class 2 data circuit and ensures that the
ECM is able to transmit serial data.
3. This test ensures that the ECM is capable of
controlling the MIL (ªCheck Engineº lamp) and the
MIL (ªCheck Engineº lamp) driver circuit is not
shorted to ground.
4. If the engine will not start, the
Cranks But Will Not
Run
chart should be used to diagnose the condition.
7. A Tech 2 parameter which is not within the typical
range may help to isolate the area which is causing
the problem.
9. When the ECM is replaced, the characteristic data of
injector and rail pressure sensor should be inputted.

6E±38
4JX1±TC ENGINE DRIVEABILITY AND EMISSIONS
On- Board Diagnostic (OBD) System Check

StepActionValue(s)Ye sNo
11. Ignition ªON,º engine ªOFF.º
2. Observe the malfunction indicator lamp (MIL or
ªCheck Engineº lamp).
Is the MIL (ªCheck Engineº lamp)ªON?º
ÐGo to Step 2
Go to No MIL
(ªCheck
Engineº lamp)
21. Ignition ªOFF.º
2. Install a Tech 2.
3. Ignition ªON.º
4. Attempt to display ECM engine data with the Tech 2.
Does the Tech 2 display ECM data?
ÐGo to Step 3Go to Step 8
31. Using the Tech 2 output tests function, select MIL
(ªCheck Engineº lamp) dash lamp control and
command the MIL (ªCheck Engineº lamp) ªOFF.º
2. Observe the MIL (ªCheck Engineº lamp).
Did the MIL (ªCheck Engineº lamp) turn ªOFF?º
ÐGo to Step 4
Go to MIL
(ªCheck
Engineº lamp)
On Steady
4Attempt to start the engine.
Did the engine start and continue to run?
ÐGo to Step 5
Go to Cranks
But Will Not
Run
5Select ªDisplay DTCsº with the Tech 2.
Are any DTCs stored?
ÐGo to Step 6Go to Step 7
6Are two or more of the following DTCs stored?
A Group; P0337, P0342, P1193, P1404, P1405,
P1488
B Group; P0337, P0342
C Group; P0112, P0117, P0182, P0197
D Group; P0107, P0405, P1194, P1485
Ð
Go to Chart,
ªMultiple
ECM
Information
Sensor DTCs
Setº
Go to
applicable
DTC table
7Compare ECM data values displayed on the Tech 2 to
the typical engine scan data values.
Are the displayed values normal or close to the typical
values?
ÐGo to Step 8
Refer to
indicated
Component
System
Checks
81. Ignition ªOFF,º disconnect the ECM.
2. Ignition ªON,º engine ªOFF.º
3. Check the Class 2 data circuit for an open, short to
ground, or short to voltage. Also, check the DLC
ignition feed circuit for an open or short to ground
and the DLC ground circuit for an open.
4. If a problem is found, repair as necessary.
Was a problem found?
ÐGo to Step 2Go to Step 9
9Check the Tech 2 on other vehicle.
Was Tech 2 abnormal?
ÐGo to Step 11Go to Step 10
10Replace the ECM (Refer to the Data Programming in
Case of ECM change).
Is the action complete?
ÐGo to Step 2Ð
11Repair the Tech 2 or prepare another Tech 2.
Is the action complete?
ÐGo to Step 2Ð