1998 ISUZU TROOPER Ecm

6E±183 4JX1±TC ENGINE DRIVEABILITY AND EMISSIONS
Rough, Unstable, or Incorrect Idle, Stalling Symptom

StepActionValue(s)Ye sNo
1DEFINITION:
Engine runs unevenly at idle. If severe, the engine or
vehicle may shake. Engine idle speed may vary in
RPM. Either condition may be severe enough to stall
the engine.
Was the ªOn-Board Diagnostic (OBD) System Checkº
performed?
ÐGo to Step 2
Go to OBD
System
Check
21. Perform a bulletin search.
2. If a bulletin that addresses the symptom is found,
correct the condition as instructed in the bulletin.
Was a bulletin found that addresses the symptom?
ÐGo to Step 6Go to Step 3
3Was a visual/physical check performed?
ÐGo to Step 4
Go to Visual/
Physical
Check
41. Check the ECM grounds for cleanliness, tightness
and proper routing. Refer to the ECM wiring
diagrams in
Electrical Diagnosis.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 5
51. Check for incorrect idle speed. Ensure that the
following conditions are present:

The engine is fully warm.

The accessories are ªOFF.º
2. Using a Tech 2, monitor the AP position.
Is the AP position within the specified values?
0%Go to Step 10Go to Step 9
61. Visually/physically inspect for the following
conditions:

Restricted air intake system. Check for a
possible collapsed air intake duct, restricted
air filter element, or foreign objects blocking
the air intake system.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 7
71. Injector Test
Operate the each injector by Tech 2 with the
ignition ªONº and check if the working noise
confirm.
2. If a problem is found, check the harness or replace
the injector.
Is the action complete?
ÐVerify repairGo to Step 8
81. Check the transmission range switch circuit. Use a
Tech 2 and be sure the Tech 2 indicates that the
vehicle is in drive with the gear selector in drive or
overdrive.
2. If a problem is found, diagnose and repair the
transmission range switch as necessary (Refer to
Automatic Transmission Diagnosis).
Was a problem found?
ÐVerify repairGo to Step 9

6E±189 4JX1±TC ENGINE DRIVEABILITY AND EMISSIONS
Cuts Out, Symptom

StepActionValue(s)Ye sNo
1DEFINITION:
Steady pulsation or jerking that follows engine speed;
usually more pronounced as engine load increases.
Was the ªOn-Board Diagnostic (OBD) System Checkº
performed?
ÐGo to Step 2
Go to OBD
System
Check
21. Perform a bulletin search.
2. If a bulletin that addresses the symptom is found,
correct the condition as instructed in the bulletin.
Was a bulletin found that addresses the symptom?
ÐGo to Step 7Go to Step 3
3Was a visual/physical check performed?
ÐGo to Step 4
Go to Visual/
Physical
Check
41. Check the ECM grounds for clearness, tightness
and proper routing. Refer to the ECM wiring
diagrams in
Electrical Diagnosis.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 5
51. Check for incorrect idle speed. Ensure that the
following conditions are present:

The engine is fully warm.

The accessories are ªoff.º
2. Using a Tech 2, monitor the AP position.
Is the AP position within the specified values?
0%Go to Step 6Go to Step 7
61. Visually/physically inspect for the following
conditions:

Restricted air intake system. Check for a
possible collapsed air intake duct, restricted
air filter element, or foreign objects blocking
the air intake system.

Check the Throttle body.

Large vacuum leak. Check for a condition that
causes a large vacuum leak, such as an
incorrectly installed or faulty VSV or brake
booster hose disconnected .
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 7
7Using a Tech 2, monitor the AP angle with the engine
idling.
Is the AP angle at the specified value and steady?
0%Go to Step 8
Refer to DTC
P0123
for
further
diagnosis
81. Check the transmission range switch circuit. Use a
Tech 2 and be sure the Tech 2 indicates that the
vehicle is in drive with the gear selector in drive or
overdrive.
2. If a problem is found, diagnose and repair the
transmission range switch as necessary.
Was a problem found?
ÐVerify repairGo to Step 9

6E±199 4JX1±TC ENGINE DRIVEABILITY AND EMISSIONS
Default Matrix Table
Service Procedure Default Strategy
A referral strategy has been established to assist the
technician with additional information when the cause ofthe failure cannot be determined. If no problem is found
after performing diagnostics, then refer to the default
matrix table for further diagnostic information.
Default Matrix Table
Strategy Based Diagnostic ChartsInitial DiagnosisDefault Section(s)
On-Board Diagnostic (OBD) System
CheckVehicle does not enter diagnostics.Chassis Electrical
On-Board Diagnostic (OBD) System
CheckVehicle enters diagnostics and
communicates with the Tech 2. MIL is
ªONº in diagnostics. Engine does not
start and run.HEUI System Check
On-Board Diagnostic (OBD) System
CheckEngine starts and runs, no ECM codes
set. Customer complains of vibration.Ð
On-Board Diagnostic (OBD) System
CheckEngine starts and runs, no ECM codes
set. Customer complains of harsh or
soft shift, poor performance, delayed or
no engagement into drive or reverse,
transmission fluid leak, transmission
noise or vibration, or improper TCC
operation.Automatic Transmission
ECM Power and Ground CheckOn-Board Diagnostic (OBD) System
Check.Chassis Electrical
ECM Power and Ground CheckOn-Board Diagnostic (OBD) System
Check. ECM power and ground circuits
OK. Data link voltage incorrect.Chassis Electrical
On-Board Diagnostic (OBD) System
CheckEngine starts and runs, no ECM codes
set. Customer complains of harsh or
soft shift, poor performance, delayed or
no engagement into drive or reverse,
transmission fluid leak, transmission
noise or vibration, or improper TCC
operation.Automatic Transmission
SymptomsInitial DiagnosisDefault Section(s)
Intermittents1. On-board diagnostic (OBD)
system check.
2. Careful visual/physical inspections.Chassis Electrical
Hard Starts1. OBD system check.
2. Sensors (ECT, MAP, EGR, AP) ;
output chart.
3. Fuel system electrical test, fuel
system diagnosis.
4. Injector system.Engine Mechanical, Injector
System Check, Exhaust System
Diagnosis
Surges and/or Chuggles1. OBD system check.
2. Fuel system diagnosis.
3. Injector system.Calibration ID ªBroadcastº
/Service Bulletins, Ignition
System Check, Generator
Output, Exhaust System
Diagnosis
Lack of Power, Sluggish or Spongy1. OBD system check.
2. Fuel system diagnosis.
3. Injector system.Refer to Exhaust System in
Engine Exhaust, TCC
Operation, Calibration
ID/Service Bulletins

6E±206
4JX1±TC ENGINE DRIVEABILITY AND EMISSIONS
3. Disconnect the electrical connector from the OT
sensor.
4. Remove the OT sensor.
035RW061
Installation Procedure
1. Install the OT sensor.
035RW061
2. Connect the OT sensor electrical connector.
3. Install the battery.
035RW095
4. Connect the negative battery cable.
Malfunction Indicator Lamp
(MIL)
Removal and Installation Procedure
Refer to Meter in Electrical section.
Engine Control Module (ECM)
Service Precaution
NOTE: To p r e ve n t p ossible electrostatic discharge
damage to the ECM, do not touch the connector pins or
soldered components on the circuit board.
When replacing the ECM to prevent possible electro
damage, follow these guidelines:
Before removing the ECM, disconnect the negative
battery cable.
Before install the ECM, install the negative battery cable.
Electrostatic Discharge (ESD)
Damage
Electronic components used in the control systems are
often designed to carry very low voltage. Electronic
components are susceptible to damage caused by
electrostatic discharge. Less than 100 volts of static
electricity can cause damage to some electronic
components. By comparison, it takes as much as 4,000
volts for a person to even feel the zap of a static
discharge.
There are several ways for a person to become statically
charged. The most common methods of charging are by
friction and by induction. An example of charging by
friction is a person sliding across a car seat.
Charging by induction occurs when a person with well
insulated shoes stands near a highly charged object and
momentarily touches ground. Charges of the same
polarity are drained off leaving the person highly charged
with the opposite polarity. Static charges can cause

6E±207 4JX1±TC ENGINE DRIVEABILITY AND EMISSIONS
damage, therefore, it is important to use care when
handling and testing electronic components.
NOTE: To prevent possible Electrostatic Discharge
damage, follow these guidelines:

Do not touch the control module connector pins or
soldered components on the control module circuit
board.

Do not open the replacement part package until the
part is ready to be installed.

Before removing the part from the package, ground
the package to a known good ground on the vehicle.

If the part has been handled while sliding across the
seat, or while sitting down from a standing position, or
while walking a distance, touch a known good ground
before installing the part.
NOTE: To prevent internal ECM damage, the ignition
must be in the ªOFFº position in order to disconnect or
reconnect power to the ECM (for example: battery cable,
ECM pigtail, ECM fuse, jumper cables, etc.).
IMPORTANT:When replacing the production ECM
with a service ECM, it is important to transfer the
broadcast code and production ECM number to the
service ECM label. This will allow positive identification of
ECM parts throughout the service life of the vehicle. Do
not record this information on the metal ECM cover.
IMPORTANT:The ignition should always be in the
ªOFFº position in order to install or remove the ECM
connectors.
Service of the ECM should normally consist of either re-
placement of the ECM. If the diagnostic procedures call
for the ECM to be replaced, the ECM should be checked
first to ensure it is the correct part. If it is, remove the
faulty ECM and install the new service ECM.
DTC P0601 indicates the check sum error.
Removal Procedure
1. Disconnect the negative battery cable.
2. Disconnect the ECM connector.
035RW093
3. Remove the bolts ECM bracket and battery bracket.
035RW094
4. Remove the ECM.
035RW092

6E±208
4JX1±TC ENGINE DRIVEABILITY AND EMISSIONS
Installation Procedure
1. Install the ECM.
035RW092
2. Install the bolts, ECM bracket and battery bracket.
035RW094
3. Connect the ECM connector.
035RW093
4. Connect the negative battery cable.
If the ECM is replaced, the new ECM will need to be
programmed.
EEPROM
General Description
The Electronically Erasable Programmable Read Only
Memory (EEPROM) is a permanent memory that is
physically soldered within the ECM. The EEPROM
contains program and calibration information that the
ECM needs to control powertrain operation.
Functional Check
1. Perform the On-Board Diagnostic System Check.
2. Start the engine and run for one minute.
3. Scan for DTCs using the Tech 2.
Intake Throttle Position (ITP)
Sensor
Removal Procedure
1. Disconnect the negative battery cable.

6E±220
4JX1±TC ENGINE DRIVEABILITY AND EMISSIONS
Installation Procedure
1. Install the EVRV.
035RW064
2. Connect the EVRV hose and the EVRV connector.
035RW065
3. Connect the negative battery cable.
Wiring and Connectors
Wiring Harness Service
The ECM harness electrically connects the ECM to the
various solenoids, switches and sensors in the vehicle
engine compartment and passenger compartment.
Replace wire harnesses with the proper part number
replacement.
Because of the low amperage and voltage levels utilized
in powertrain control systems, it is essential that all wiring
in environmentally exposed areas be repaired with crimp
and seal splice sleeves.The following wire harness repair information is intended
as a general guideline only. Refer to
Chassis Electrical for
all wire harness repair procedures.
Connectors and Terminals
Use care when probing a connector and when replacing
terminals. It is possible to short between opposite
terminals. Damage to components could result. Always
use jumper wires between connectors for circuit
checking. NEVER probe through Weather-Pack seals.
Use an appropriate connector test adapter kit which
contains an assortment of flexible connectors used to
probe terminals during diagnosis. Use an appropriate
fuse remover and test tool for removing a fuse and to
adapt the fuse holder to a meter for diagnosis.
Open circuits are often difficult to locate by sight because
oxidation or terminal misalignment are hidden by the
connectors. Merely wiggling a connector on a sensor, or
in the wiring harness, may temporarily correct the open
circuit. Intermittent problems may also be caused by
oxidized or loose connections.
Be certain of the type of connector/terminal before
making any connector or terminal repair. Weather-Pack
and Com-Pack III terminals look similar, but are serviced
differently.
Wire Harness Repair: Twisted
Shielded Cable
Removal Procedure
1. Remove the outer jacket.
2. Unwrap the aluminum/mylar tape. Do not remove the
mylar.
047

6E±225 4JX1±TC ENGINE DRIVEABILITY AND EMISSIONS
General Description
(ECM and Sensors)
57X Reference ECM Input
The engine control module (ECM) uses this signal from
the crankshaft position (CKP) sensor to calculate engine
RPM and crankshaft position at all engine speeds. The
ECM also uses the pulses on this circuit to initiate injector
pulses. If the ECM receives no pulses on this circuit, DTC
P0337 will set. The engine will not start and run without
using the 57X reference signal.
A/C Request Signal
This signal tells the ECM when the A/C mode is selected
at the A/C control head.
Refer to
A/C Clutch Circuit Diagnosis for A/C wiring
diagrams and diagnosis for the A/C electrical system.
Crankshaft Position (CKP) Sensor
The crankshaft position (CKP) sensor provides a signal
used by the engine control module (ECM) to calculate the
ignition sequence. The CKP sensor initiates the 57X
reference pulses which the ECM uses to calculate RPM
and crankshaft position.
Refer to
Electronic Ignition System for additional
information.
Camshaft Position (CMP) Sensor and
Signal
The camshaft position (CMP) sensor sends a CMP signal
to the ECM. The ECM uses this signal as a ªcylinder
distinctionº to trigger the injectors in the power order. If the
ECM detects an incorrect CMP signal while the engine is
running, DTC P0341 will set, and the ECM triggers the
injectors in the power order.
Refer to
DTC P0341.
Engine Coolant Temperature (ECT) Sensor
The engine coolant temperature (ECT) sensor is a
thermistor (a resistor which changes value based on
temperature) mounted in the engine coolant stream. Low
coolant temperature produces a high resistance of
100,000 ohms at ±40
C (±40
F). High temperature
causes a low resistance of 70 ohms at 130
C (266
F).
The ECM supplies a 5-volt signal to the ECT sensor
through resistors in the ECM and measures the voltage.
The signal voltage will be high when the engine is cold and
low when the engine is hot. By measuring the voltage, the
ECM calculates the engine coolant temperature. Engine
coolant temperature affects most of the systems that the
ECM controls.
The Tech 2 displays engine coolant temperature in
degrees. After engine start-up, the temperature should
rise steadily to about 85
C (185
F). It then stabilizes
when the thermostat opens. If the engine has not been
run for several hours (overnight), the engine coolanttemperature and intake air temperature displays should
be close to each other. A hard fault in the engine coolant
sensor circuit will set DTC P0117 or DTC P0118.
0016
Electrically Erasable Programmable Read
Only Memory (EEPROM)
The electrically erasable programmable read only
memory (EEPROM) is a permanent memory chip that is
physically soldered within the ECM. The EEPROM
contains the program and the calibration information that
the ECM needs to control powertrain operation.
Unlike the PROM used in past applications, the EEPROM
is not replaceable. If the ECM is replaced, the new ECM
will need to be programmed. Equipment containing the
correct program and calibration for the vehicle is required
to program the ECM.
Intake Air Temperature (IAT) Sensor
The intake air temperature (IAT) sensor is a thermistor
which changes its resistance based on the temperature of
air entering the engine. Low temperature produces a high
resistance of 100,000 ohms at ±40
C (±40
F). High
temperature causes low resistance of 70 ohms at 130
C
(266
F) . The ECM supplies a 5-volt signal to the sensor
through a resistor in the ECM and monitors the signal
voltage. The voltage will be high when the incoming air is
cold. The voltage will be low when the incoming air is hot.
By measuring the voltage, the ECM calculates the
incoming air temperature.
The Tech 2 displays the temperature of the air entering
the engine. The temperature should read close to the
ambient air temperature when the engine is cold and rise
as underhood temperature increases. If the engine has
not been run for several hours (overnight), the IAT sensor
temperature and engine coolant temperature should read
close to each other. A fault in the IAT sensor circuit will set
DTC P0112 or DTC P0113.