check engine ISUZU TROOPER 1998 Service Repair Manual

6E±196
4JX1±TC ENGINE DRIVEABILITY AND EMISSIONS
QOS System Doesn't Work

StepActionValue(s)Ye sNo
1Was OBD System check performed?
ÐGo to Step 2
Go to OBD
System
Check
2Check glawplug indicator light. If bulb is broken,
replace.
Was a problem found?
ÐVerify repairGo to Step 3
31. Connect a circuit tester between glawplug & engine
ground.
2. With ignition on and engine off, check if the glaw
indicator and circuit tester indicate power voltage
for 9 to 13 sec. If not indicated, repair terminal & wire
harness.
Was repair needed?
ÐVerify repairGo to Step 4
41. Connect a circuit tester between glawplug and
engine ground.
2. With engine on, check if voltage continues for 180
sec. If not, inspect and repair glaw relay.
Was repair needed?
ÐVerify repairGo to Step 5
51. Remove the glawplug, and if damaged, replace.
2. Check glawplug resistance.
Was resistance as specified?
0.8 ± 1
Go to Step 7Go to Step 6
6Replace glawplug.
Was measure completed?
ÐVerify repairGo to Step 7
71. Review all diagnostic procedures within this table.
2. If all procedures have been completed and no
malfunctions have been found, review/inspect the
following:

Visual/physical inspection

Tech 2 data

Freeze Frame data/Failure Records butter

All electrical connections within a suspected
circuit and/or system
3. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repair
Contact
Technical
Assistance

6E±197 4JX1±TC ENGINE DRIVEABILITY AND EMISSIONS
Much Black Smoke in Exhaust Gas

StepActionValue(s)Ye sNo
1DEFINITION:
In road tests, much black smoke is mixed.
Was OBD System check performed?
ÐGo to Step 2
Go to OBD
System
Check
21. Perform a bulletin research.
2. If a bulletin that addresses the symptom is found,
correct the condition as instructed in the bulletin.
Was a bulletin found?
ÐVerify repairGo to Step 3
31. Check if a correct fuel is used.
2. If a problem is found, change fuel.
Was a problem found?
ÐVerify repairGo to Step 4
41. Check air cleaner element for clogging.
2. If a problem is found, repair or replace as
necessary.
Was a problem found?
ÐVerify repairGo to Step 5
51. Connect Tech 2 to the vehicle.
2. Monitor data list to check injector function.
3. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 6
61. Connect Tech 2 to the vehicle.
2. Monitor RPCV test to check rpcv function.
3. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 7
71. Check valve clearance.
2. If a problem is found, adjust as necessary.
Was a problem found?
ÐVerify repairGo to Step 8
81. Review all diagnostic procedures in this table.
2. If all procedures have been completed and no
malfunctions have been found, review/inspect the
following:

Visual/physical check

Tech 2 data list

Freeze Frame data

All electrical connections in suspected circuits
& systems
3. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repair
Contact
Technical
Assistance

6E±198
4JX1±TC ENGINE DRIVEABILITY AND EMISSIONS
Excess Engine Oil Consumption

StepActionValue(s)Ye sNo
1DEFINITION:
Oil consumption measured in road tests is higher than
expected.
Was OBD System check performed?
ÐGo to Step 2
Go to OBD
System
Check
21. Perform a bulletin research.
2. If a bulletin that addresses the symptom is found,
correct the condition as instructed in the bulletin.
Was a bulletin found?
ÐVerify repairGo to Step 3
31. Check if a correct engine oil is used.
2. If a problem is found, change engine oil.
Was a problem found?
ÐVerify repairGo to Step 4
41. Check oil pipe connections for leakage.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 5
51. Check oil seals and gaskets for leakage.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 6
61. Connect Tech 2 to the vehicle.
2. Perform RPCV test to check its function.
3. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 7
71. Check piston ring for damage & groove wear.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 8
81. Check valve stem, valve guide and oil controller for
wear.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 9
91. Check camshaft carrier & cylinder head gaskets for
blow-by.
2. If a problem is found, repair or replace as
necessary.
Was a problem found?
ÐVerify repairGo to Step 10
101. Review all the diagnostic procedures in this table.
2. If all procedures have been completed and no
malfunctions have been found, review/inspect the
following:

Visual/physical check

Tech 2 data list

Freeze Frame data

All electrical connections in suspected circuits
& systems
3. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repair
Contact
Technical
Assistance

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±200
4JX1±TC ENGINE DRIVEABILITY AND EMISSIONS
SymptomsInitial DiagnosisDefault Section(s)
Hesitation, Sag, Stumble1. OBD system check.
2. AP.
3. MAP output check.
4. Fuel system diagnosis.
5. Injector system.Generator Output Voltage (refer
to
Chassis Electrical),
Calibration ID/Service Bulletins,
Ignition System Check
Rough, Unstable, or Incorrect Idle,
Stalling1. OBD system check.
2. Fuel injector test.MAP Output Check, Throttle
Linkage, A/C Clutch Control
Circuit Diagnosis, Calibration
ID/Service Bulletins, Generator
Output Voltage (refer to
Chassis
Electrical
), Exhaust Diagnosis
Poor Fuel Economy1. OBD system check.
2. Careful visual/physical inspection.
3. Injector system.
4. Cooling system.TCC Operation, Exhaust
System (refer to
Engine
Exhaust
)
Engine Cranks But Will Not Run1. OBD system check.Fuel System Electrical
Diagnosis, Fuel System
Diagnosis, Fuel Injector Test.
Excessive Exhaust Emissions or
Odors1. OBD system check.
2. Emission test.
3. Cooling system.
4. Fuel system diagnosis.
5. Fuel injector test.
6. Injector system.
7. MAP output check.Exhaust Diagnosis, Calibration
ID/Service Bulletins
Dieseling, Run-On1. OBD system check.
2. Careful visual/physical inspection.
3. Fuel system diagnosis.Ð

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±209 4JX1±TC ENGINE DRIVEABILITY AND EMISSIONS
2. Remove the cover of the intercooler.
035RW051
3. Remove the bolts and the left side bracket to the
intercooler.
4. Remove the air duct with bracket from the intercooler.
5. Remove the throttle body from the intake manifold.
6. Disconnect the ITP sensor electrical connector and
throttle motor control connector.
7. Remove the bolts and the ITP sensor from the throttle
body.
035RW086
NOTE: Do not clean the ITP sensor by soaking it in
solvent. The sensor will be damaged as a result.
Function Check
Use a Tech 2 to check the ITP sensor output voltage at
closed throttle.

The voltage should be under 0.85 volt.

If the reading is greater than 0.85 volt, check the
throttle shaft to see if it is binding.
If the throttle shaft is not binding and the throttle cable
is properly adjusted, install a new ITP sensor.
Installation Procedure
1. Install the ITP sensor on the throttle body with the
bolts.
035RW051
2. Install the throttle body to the intake manifold and the
air duct with bracket between throttle body and
intercooler.
Torque: 20 N´m (14 Ib ft)
035RW086
3. Connect the ITP sensor electrical connector and
throttle motor control connector.
4. Install the bracket to the intercooler.
5. Install the cover of intercooler.
6. Install the negative battery cable.

6E±210
4JX1±TC ENGINE DRIVEABILITY AND EMISSIONS
Vehicle Speed Sensor (VSS)
Removal Procedure
CAUTION: The VSS is located on the right side of
the transfer case just ahead of the rear propeller
shaft and very close to the exhaust pipes. Be sure
that the exhaust pipes are cool enough to touch
before trying to remove the VSS. If the pipes are hot,
you could be burned.
1. Disconnect the negative battery cable.
2. Disconnect the VSS electrical connector.
TS23748
3. Remove the bolt and the clamp securing the VSS in
place.
IMPORTANT:Have a container ready to catch any fluid
that leaks out when the VSS is removed from the transfer
case.
TS23780
4. Remove the VSS from the transfer case by wiggling it
slightly and pulling it straight out.
Inspection Procedure
1. Inspect the electrical connector for signs of corrosion
or warping. Replace the VSS if the electrical
connector is corroded or warped.
2. Inspect the VSS driven gear for chips, breaks, or worn
condition. Replace the VSS if the driven gear is
chipped, broken or worn.
3. Inspect the O-ring for wear, nicks, tears, or
looseness. Replace the O-ring if necessary.
Installation Procedure
1. Install the VSS in the transfer case with the notch for
the connector facing the rear.
2. Secure the VSS in place with the clamp and the bolt.
Tighten

Tighten the bolt to 16 N´m (12 lb ft.).
TS23780
3. Connect the VSS electrical connector.
TS23748
4. Check the transfer case oil level. Add fluid if
necessary.

6E±213 4JX1±TC ENGINE DRIVEABILITY AND EMISSIONS
3. Connect the electrical connector to the AP sensor.
035RW060
4. Connect the negative battery cable.
Fuel Filter Cap
General Description
The fuel filler cap includes a vacuum valve and a pressure
valve.
If high vacuum or high pressure occurs in the fuel tank,
each valve works to adjust the pressure in order to
prevent damage to the tank at the EGR valve.
TS23767
Inspection Procedure
NOTE: Replace the fuel filler cap with the same type of
filler cap that was originally installed on the vehicle.

Check the seal ring in the filler cap for any abnormality
and for seal condition.

Replace the filler cap if any abnormality is found.
Fuel Filter
Removal and Installation Procedure
Refer to the Engine fuel in the 4JX1 Engine section.
Fuel Gauge Unit
Removal Procedure
1. Disconnect the negative battery cable.
2. Loosen the fuel filler cap.
3. Drain the fuel from the tank.
Tighten

Tighten the drain plug to 20 N´m (14 lb ft.).
TS22907
4. Disconnect the wiring connector from the fuel gauge
unit.
TS23771
5. Remove the fuel gauge unit retaining screws.