1998 ISUZU TROOPER length

6E±38
ENGINE DRIVEABILITY AND EMISSIONS
General Service Information
OBD Serviceablity Issues
The list of non-vehicle faults that could affect the
performance of the OBD system has been compiled.
These non-vehicle faults vary from environmental
conditions to the quality of fuel used.
The illumination of the MIL (ªCheck Engineº lamp) due to
a non-vehicle fault could lead to misdiagnosis of the
vehicle, increased warranty expense and customer
dissatisfaction. The following list of non-vehicle faults
does not include every possible fault and may not apply
equally to all product lines.
Fuel Quality
Using fuel with the wrong octane rating for your vehicle
may cause driveability problems. Many of the major fuel
companies advertise that using ªpremiumº gasoline will
improve the performance of your vehicle. Most premium
fuels use alcohol to increase the octane rating of the fuel.
Although alcohol-enhanced fuels may raise the octane
rating, the fuel's ability to turn into vapor in cold
temperatures deteriorates. This may affect the starting
ability and cold driveability of the engine.
Low fuel levels can lead to fuel starvation, lean engine
operation, and eventually engine misfire.
Non-OEM Parts
All of the OBD diagnostics have been calibrated to run
with OEM parts. Something as simple as a
high-performance exhaust system that affects exhaust
system back pressure could potentially interfere with the
operation of the EGR valve and thereby turn on the MIL
(ªCheck Engineº lamp). Small leaks in the exhaust
system near the post catalyst oxygen sensor can also
cause the MIL (ªCheck Engineº lamp) to turn on.
Aftermarket electronics, such as cellular phones,
stereos, and anti-theft devices, may radiate EMI into the
control system if they are improperly installed. This may
cause a false sensor reading and turn on the MIL (ªCheck
Engineº lamp).
Environment
Temporary environmental conditions, such as localized
flooding, will have an effect on the vehicle ignition system.
If the ignition system is rain-soaked, it can temporarily
cause engine misfire and turn on the MIL (ªCheck Engineº
lamp).
Poor Vehicle Maintenance
The sensitivity of OBD diagnostics will cause the MIL
(ªCheck Engineº lamp) to turn on if the vehicle is not
maintained properly. Restricted air filters, fuel filters, and
crankcase deposits due to lack of oil changes or improper
oil viscosity can trigger actual vehicle faults that were not
previously monitored prior to OBD. Poor vehicle
maintenance can not be classified as a ªnon-vehicle
faultº, but with the sensitivity of OBD diagnostics, vehicle
maintenance schedules must be more closely followed.Related System Faults
Many of the OBD system diagnostics will not run if the
PCM detects a fault on a related system or component.
One example would be that if the PCM detected a Misfire
fault, the diagnostics on the catalytic converter would be
suspended until Misfire fault was repaired. If the Misfire
fault was severe enough, the catalytic converter could be
damaged due to overheating and would never set a
Catalyst DTC until the Misfire fault was repaired and the
Catalyst diagnostic was allowed to run to completion. If
this happens, the customer may have to make two trips to
the dealership in order to repair the vehicle.
Maintenance Schedule
Refer to the Maintenance Schedule.
Visual / Physical Engine Compartment
Inspection
Perform a careful visual and physical engine
compartment inspection when performing any diagnostic
procedure or diagnosing the cause of an emission test
failure. This can often lead to repairing a problem without
further steps. Use the following guidelines when
performing a visual/physical inspection:

Inspect all vacuum hoses for punches, cuts,
disconnects, and correct routing.

Inspect hoses that are difficult to see behind other
components.

Inspect all wires in the engine compartment for proper
connections, burned or chafed spots, pinched wires,
contact with sharp edges or contact with hot exhaust
manifolds or pipes.
Basic Knowledge of Tools Required
NOTE: Lack of basic knowledge of this powertrain when
performing diagnostic procedures could result in an
incorrect diagnosis or damage to powertrain
components. Do not attempt to diagnose a powertrain
problem without this basic knowledge.
A basic understanding of hand tools is necessary to effec-
tively use this section of the Service Manual.
Serial Data Communications
Class II Serial Data Communications
This vehicle utilizes the ªClass IIº communication system.
Each bit of information can have one of two lengths: long
or short. This allows vehicle wiring to be reduced by
transmitting and receiving multiple signals over a single
wire. The messages carried on Class II data streams are
also prioritized. If two messages attempt to establish
communications on the data line at the same time, only
the message with higher priority will continue. The device
with the lower priority message must wait. The most
significant result of this regulation is that it provides Tech 2
manufacturers with the capability to access data from any
make or model vehicle that is sold.

6E±91 ENGINE DRIVEABILITY AND EMISSIONS
Fuel System Diagnosis

 
StepNo Ye s Value(s) Action
10Locate and repair the loss of vacuum to the fuel
pressure regulator.
Is the action complete?
ÐVerify repairÐ
11Replace the fuel pressure regulator.
Is the action complete?
ÐVerify repairÐ
121. Run the fuel pump with Tech 2.
2. After pressure has built up, turn off the pump and
clamp the supply hose shut with suitable locking
pliers.
Does the fuel pressure indicated by the fuel pressure
gauge remain constant?
ÐGo to Step 13Go to Step 15
13Visually inspect the fuel supply line and repair any
leaks.
Was a problem found?
ÐVerify repairGo to Step 14
14Remove the fuel tank and inspect for leaky hose or
in-tank fuel line.
Was a problem found?
ÐVerify repairGo to Step 8
151. If the pliers are still clamped to the fuel supply hose,
remove the locking pliers.
2. With suitable locking pliers, clamp the fuel return
line to prevent fuel from returning to the fuel tank.
3. Run the fuel pump with Tech 2.
4. After pressure has built up, remove power to the
pump.
Does the fuel pressure indicated by the fuel pressure
gauge remain constant?
ÐGo to Step 11Go to Step 16
16Locate and replace any leaking fuel injector(s).
Is the action complete?
ÐVerify repairÐ
17Is the fuel pressure indicated by the fuel pressure
gauge above the specified limit?376 kPa
(55 psi)
Go to Step 18Go to Step 21
181. Relieve the fuel pressure. Refer to the Fuel
Pressure Relief.
2. Disconnect the fuel return line from the fuel rail.
3. Attach a length of flexible hose to the fuel rail return
outlet passage.
4. Place the open end of the flexible hose into an
approved gasoline container.
5. Run the fuel pump with Tech 2.
6. Observe the fuel pressure indicated by the fuel
pressure gauge with the fuel pump running.
Is the fuel pressure within the specified limits?
290-376 kPa
(42-55 psi)
Go to Step 19Go to Step 20
19Locate and correct the restriction in the fuel return line.
Is the action complete?
ÐVerify repairÐ
20Visually and physically inspect the fuel rail outlet
passages for a restriction.
Was a restriction found?
ÐVerify repairGo to Step 11
21Is the fuel pressure indicated by the fuel pressure
gauge above the specified value?
0 kPa (0 psi)Go to Step 22Go to Step 23

6D2 Ð 8 STARTING SYSTEM
·Polish the commutator surface with sand paper #500
to #600 if it is rough.
·Measure the depth of insulator in commutator. Re-
pair, if it is below the limit.
Brush
·Measure the length of brush.
Replace with a new one, if it is below the limit.
Brush holder
·Check for continuity between brush holder (+) and
base (-). Replace, if there is continuity (i.e., insulation
is broken).
·Inspect the brush springs for wear, damage or other
abnormal conditions.
Standard Limit
0.5 ~ 0.8 (0.02 ~ 0.03) 0.2 (0.008)mm(in)
Standard Limit
18.0 (0.71) 11.0 (0.43)mm(in)
Standard
28-35 (2.9-3.6/6.4-7.9)N (Kg/lb)

6D3 Ð 8 CHARGING SYSTEM
DIODE
1. Check for continuity across the terminal (example:
across BAT and U). If a continuity exists, the diode is
in satisfactory condition. If no continuity exists the
diode is defective.
2. Make a test with the polarities reversed. If no
continuity exists, the diode is in satisfactory
condition. If a continuity exists at any point, the
diode is defective and should be replaced.
Auxiliary diodes are not provided with the terminal
and continuity test should be made across the
terminals of the conventional diodes.
BRUSH
Measure length of brushes.
Brush length (L)
Across terminals BAT (Positive side (+) diodes)
Tester pin
Positive side
Negative sidePositive side
ContinuityNegative side
No continuity
U.V.W.
Across terminals BAT (Positive side (+) diodes)
Tester pin
Positive side
Negative sidePositive side
ContinuityNegative side
No continuity
U.V.W.
20(0.7) 6 (0.24)mm(in)
Standard Limit
Brushes are provided with a line which indicates the
limit of usage.

6D3 Ð 10 CHARGING SYSTEM
VACUUM PUMP
Visual check
¥ Inspect the following parts for wear, damage or other
abnormal conditions.
Standard60.0 – 60.1
(2.362 – 2.366)mm (in)
Vane
Measure the length of vanes
Standard 14.2– 15.2(0.559–0.598)mm (in)
Check valve
1. Apply a light pressure onto the ÓBÓ side of valve with
a screw driver and check that valve operates
smoothly.
2. Apply compressed air onto ÓAÓ side of valve and
check if there is air leak.
Housing
¥ Measure the inside diameter of housing and place if it
exceed the standard.
Reassembly of vacuum pump
1. Position the rotor, with the serrated boss turned up,
on the center plate and housing.
Align the holes in center plate and rotor.
2. Install vanes into slits in rotor.
The vanes should be installed with chamfered side
turned outward.
3. Install the O-ring and center plate
Disassembly of Vacuum pump
¥ For the center plate, rotor and vane in the mentioned.

ENGINE ELECTRICAL 6D – 11
5) Polish the commutator surface with sand paper
#500 to #600 if it is rough.
6) Measure the depth of insulator in commutator.
Repair, if it is below the limit.
Standard: 0.5 – 0.8 mm (0.02 – 0.03 in)
Limit: 0.2 mm (0.008 in)
Legend
(1) Steel Saw
(2) Chamfer
(3) Correct Condition
(4) Depth of Insulator
(5) Incorrect Condition
(6) Insulator
(7) Commutator SegmentBrush
1) Measure the length of brush.
Replace with a new one, if it is below the limit.
Standard: 18.0 mm (0.71 in)
Limit: 11.0 mm (0.43 in)
Brush holder
1) Check for continuity between brush holder (+) and
base (–). Replace, if there is continuity (i.e.,
insulation is broken).
065RW105
1
6
53 42 7
065RW102
065RW103
065RW104

6D – 20 ENGINE ELECTRICAL
4. Check for continuity between slip ring and rotor
core.
In case of continuity, replace the rotor assembly.
Stator Coil
1. Check for continuity across the stator coils. If no
continuity exists, replace the coils.
Resistance value at 20°C
Standard: Approx 0.07Ω2. Check for continuity across one of the stator coils
and stator core. If a continuity exists, replace the
coil.
Standard: More than 1MΩBrush
Measure the brush length.
If more than limit, replace the brush.
Standard: 18.0 mm (0.709 in)
Limit: 5.5 mm (0.217 in)
´

µ

066RS017
066RS035
066RW024066RS034

6E±25 4JX1±TC ENGINE DRIVEABILITY AND EMISSIONS
General Service Information
Serviceability Issues
Non-OEM Parts
All of the OBD diagnostics have been calibrated to run
with OEM parts. Accordingly, if commercially sold sensor
or switch is installed, it makes a wrong diagnosis and turn
on the MIL (ªCheck Engineº lamp).
Aftermarket electronics, such as cellular phones,
stereos, and anti-theft devices, may radiate EMI into the
control system if they are improperly installed. This may
cause a false sensor reading and turn on the MIL (ªCheck
Engineº lamp).
Poor Vehicle Maintenance
The sensitivity of OBD diagnostics will cause the MIL
(ªCheck Engineº lamp) to turn on if the vehicle is not
maintained properly. Restricted oil filters, fuel filters, and
crankcase deposits due to lack of oil changes or improper
oil viscosity can trigger actual vehicle faults that were not
previously monitored prior to OBD. Poor vehicle
maintenance can not be classified as a ªnon-vehicle
faultº, but with the sensitivity of OBD diagnostics, vehicle
maintenance schedules must be more closely followed.
Related System Faults
Many of the OBD system diagnostics will not run if the
ECM detects a fault on a related system or component.
Visual/Physical Engine Compartment
Inspection
Perform a careful visual and physical engine
compartment inspection when performing any diagnostic
procedure or diagnosing the cause of an emission test
failure. This can often lead to repairing a problem without
further steps. Use the following guidelines when
performing a visual/physical inspection:

Inspect all vacuum hoses for punches, cuts,
disconnects, and correct routing.

Inspect hoses that are difficult to see behind other
components.

Inspect all wires in the engine compartment for proper
connections, burned or chafed spots, pinched wires,
contact with sharp edges or contact with hot exhaust
manifolds or pipes.
Basic Knowledge of Tools Required
NOTE: Lack of basic knowledge of this powertrain when
performing diagnostic procedures could result in an
incorrect diagnosis or damage to powertrain
components. Do not attempt to diagnose a powertrain
problem without this basic knowledge.
A basic understanding of hand tools is necessary to effec-
tively use this section of the Service Manual.
Serial Data Communications
Class II Serial Data Communications
This vehicle utilizes the ªClass IIº communication system.
Each bit of information can have one of two lengths: longor short. This allows vehicle wiring to be reduced by
transmitting and receiving multiple signals over a single
wire. The messages carried on Class II data streams are
also prioritized. If two messages attempt to establish
communications on the data line at the same time, only
the message with higher priority will continue. The device
with the lower priority message must wait.
On this vehicle the Tech 2 displays the actual values for
vehicle parameters. It will not be necessary to perform
any conversions from coded values to actual values.
On-Board Diagnostic (OBD)
On-Board Diagnostic Tests
A diagnostic test is a series of steps, the result of which is
a pass or fail reported to the diagnostic executive. When
a diagnostic test reports a pass result, the diagnostic
executive records the following data:

The diagnostic test has been completed since the last
ignition cycle.

The diagnostic test has passed during the current
ignition cycle.

The fault identified by the diagnostic test is not
currently active.
When a diagnostic test reports a fail result, the diagnostic
executive records the following data:

The diagnostic test has been completed since the last
ignition cycle.

The fault identified by the diagnostic test is currently
active.

The fault has been active during this ignition cycle.

The operating conditions at the time of the failure.
Comprehensive Component Monitor
Diagnostic Operation
Comprehensive component monitoring diagnostics are
required to operate engine properly.
Input Components:
Input components are monitored for circuit continuity and
out-of-range values. This includes rationality checking.
Rationality checking refers to indicating a fault when the
signal from a sensor does not seem reasonable. Accel
Position (AP) sensor that indicates high throttle position
at low engine loads or MAP voltage. Input components
may include, but are not limited to the following sensors:

Intake Air Temperature (IAT) Sensor

Crankshaft Position (CKP) Sensor

Intake throttle Position (ITP) Sensor

Engine Coolant Temperature (ECT) Sensor

Camshaft Position (CMP) Sensor

Manifold absolute Pressure (MAP) Sensor

Accel Position Sensor

Fuel Temp Sensor

Rail Pressure Sensor

Oil Temp Sensor

EGR Pressure Sensor

Vehicle Speed Sensor