1998 ISUZU TROOPER service indicator

6E±104
ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P0101 MAF System Performance
D06RW103
Circuit Description
The mass air flow (MAF) sensor measures the amount of
air which passes through it into the engine during a given
time. The powertrain control module (PCM) uses the
mass air flow information to monitor engine operating
conditions for fuel delivery calculations. A large quantity
of air entering the engine indicates an acceleration or high
load situation, while a small quantity or air indicates
deceleration or idle.
The MAF sensor produces a frequency signal which can
be monitored using a Tech 2. DTC P0101 will be set if the
signal from the MAF sensor does not match a predicted
value based on throttle position and engine RPM.
Conditions for Setting the DTC

The engine is running.

No TP sensor or MAP sensor DTCs are set.

The throttle is steady, TP angle doesn't change by
more than 1%.

System voltage is between 11.5 volts and 16 volts.

Calculated air flow is between 25 g/second and 40
g/second.

Above conditions present for at least 1 second.

MAF signal frequency indicates an airflow significantly
higher or lower than a predicted value based on throttle
position and engine RPM for a total of 12.5 seconds
over a 25-second period of time.
Action Taken When the DTC Sets

The PCM will illuminate the malfunction indicator lamp
(MIL) after the second consecutive trip in which the
fault is detected.

The PCM calculates an airflow value based on idle air
control valve position, throttle position, RPM and
barometric pressure.

The PCM will store conditions which were present
when the DTC was set as Freeze Frame and in the
Failure Records data.
Conditions for Clearing the MIL/DTC

DTC P0101 can be cleared by using the Tech 2 ªClear
Infoº function or by disconnecting the PCM battery
feed.
Diagnostic Aids
An intermittent may be caused by the following:

Poor connections.

Mis-routed harness.

Rubbed through wire insulation.

Broken wire inside the insulation.
Refer to Intermittents under service category Symptoms.
Any un-metered air may cause this DTC to set. Check for
the following:

The duct work at the MAF sensor for leaks.

An engine vacuum leak.

The PCV system for vacuum leaks.

An incorrect PCV valve.

6E±262
ENGINE DRIVEABILITY AND EMISSIONS
Symptom Diagnosis
Preliminary Checks
Before using this section, perform the ªOn-Board
Diagnostic (OBD) System Checkº and verify all of the
following items:

The powertrain control module (PCM) and malfunction
indicator lamp (MIL) (Service Engine Soon lamp) are
operating correctly.

There are no DTC(s) stored.

Tech 2 data is within normal operating range. Refer to
Typical Scan Data Values.

Verify the customer complaint and locate the correct
symptom in the table of contents. Perform the
procedure included in the symptom chart.
Visual/Physical Check
Several of the symptom procedures call for a careful
visual/physical check. This can lead to correcting a
problem without further checks and can save valuable
time.
This check should include the following items:

PCM grounds for cleanliness, tightness and proper
location.

Vacuum hoses for splits, kinks, and proper
connections, as shown on the ªVehicle Emission
Control Informationº label. Check thoroughly for any
type of leak or restriction.

Air intake ducts for collapsed or damaged areas.

Air leaks at throttle body mounting area, mass air flow
(MAF) sensor and intake manifold sealing surfaces.

Ignition wires for cracking, hardness, and carbon
tracking.

Wiring for proper connections, pinches and cuts.
Intermittents
IMPORTANT:An intermittent problem may or may not
turn on the malfunction indicator lamp (MIL) or store a
DTC. DO NOT use the Diagnostic Trouble Code (DTC)
charts for intermittent problems. The fault must be
present to locate the problem.
Most intermittent problems are caused by faulty electrical
connections or wiring. Perform a careful visual/physical
check for the following conditions:

Poor mating of the connector halves or a terminal not
fully seated in the connector (backed out).

Improperly formed or damaged terminal.

All connector terminals in the problem circuit should be
carefully checked for proper contact tension.

Poor terminal-to-wire connection. This requires
removing the terminal from the connector body to
check.
Road test the vehicle with a J 39200 Digital Multimeter
connected to a suspected circuit. An abnormal voltage
when the malfunction occurs is a good indication that
there is a fault in the circuit being monitored.
Use Tech 2 to help detect intermittent conditions. Tech 2s
have several features that can be used to locate anintermittent condition. Use the following feature to find
intermittent faults:

Using Tech 2's ªFreeze Frameº buffer or ªFailure
Recordsº buffer can aid in locating an intermittent
condition. Review and record the information in the
freeze frame or failure record associated with the
intermittent DTC being diagnosed. The vehicle can be
driven within the conditions that were present when the
DTC originally set.
To check for loss of diagnostic code memory, disconnect
the MAP sensor and idle the engine until the MIL (Service
Engine Soon lamp) comes on. DTC P0107 should be
stored and kept in memory when the ignition is turned
ªOFF.º If not, the PCM is faulty. When this test is
completed, make sure that you clear the DTC P0107 from
memory.
An intermittent MIL (Service Engine Soon lamp) with no
stored DTC may be caused by the following:

Ignition coil shorted to ground and arcing at ignition
wires or plugs.

MIL (Service Engine Soon lamp) wire to PCM shorted
to ground.

Poor PCM grounds. Refer to the PCM wiring
diagrams.
Check for improper installation of electrical options such
as lights, cellular phones, etc. Route ignition coil wiring
away from the ignition coils. Check all wires from the
PCM to the ignition coil for poor connections.
Check for an open diode across the A/C compressor
clutch and check for other open diodes (refer to wiring
diagrams in
Electrical Diagnosis).
If problem has not been found, refer to
PCM Connector
Symptom
tables.

6E±298
ENGINE DRIVEABILITY AND EMISSIONS
4. Remove the MAP sensor from the mounting bracket.
055RW002
Installation Procedure
1. Install the MAP sensor in the mounting bracket.
055RW002
2. Install the mounting bracket retaining bolt on the
common chamber.
3. Connect the MAP electrical connector.
055RW005
4. Connect the negative battery cable.
Malfunction Indicator Lamp
(MIL)
Removal and Installation Procedure
Refer to Warning light bulb, indicator light valve,
illumination light bulb, A/T indicator light bulb in Meter and
Gauge.
Powertrain Control Module
(PCM)
Service Precaution
NOTE: To p r e ve n t p ossible electrostatic discharge
damage to the PCM, do not touch the connector pins or
soldered components on the circuit board.
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±339 ENGINE DRIVEABILITY AND EMISSIONS
0005
PCM Components
The PCM is designed to maintain exhaust emission levels
to government mandated standards while providing
excellent driveability and fuel efficiency. The PCM
monitors numerous engine and vehicle functions via
electronic sensors such as the throttle position (TP)
sensor, heated oxygen sensor (HO2S), and vehicle
speed sensor (VSS). The PCM also controls certain
engine operations through the following:

Fuel injector control

Ignition control module

Knock sensor

Automatic transmission shift functions

Cruise control

A/C clutch control
PCM Voltage Description
The PCM supplies a buffered voltage to various switches
and sensors. It can do this because resistance in the
PCM is so high in value that a test light may not illuminate
when connected to the circuit. An ordinary shop
voltmeter may not give an accurate reading because the
voltmeter input impedance is too low. Use a 10-megohm
input impedance digital voltmeter (such as J 39200) to
assure accurate voltage readings.
The input/output devices in the PCM include
analog-to-digital converters, signal buffers, counters,
and special drivers. The PCM controls most components
with electronic switches which complete a ground circuit
when turned ªON.º These switches are arranged in
groups of 4 and 7, called either a surface-mounted quad
driver module (QDM), which can independently control up
to 4 output terminals, or QDMs which can independently
control up to 7 outputs. Not all outputs are always used.
PCM Input/Outputs
Inputs ± Operating Conditions Read

Air Conditioning ªONº or ªOFFº
Engine Coolant Temperature

Crankshaft Position

Exhaust Oxygen Content

Electronic Ignition

Manifold Absolute Pressure

Battery Voltage

Throttle Position

Vehicle Speed

Fuel Pump Voltage

Power Steering Pressure

Intake Air Temperature

Mass Air Flow

Engine Knock

Camshaft Position
Outputs ± Systems Controlled

Exhaust Gas Recirculation (EGR)

Ignition Control

Fuel Control

Idle Air Control

Electric Fuel Pump

Air Conditioning

Diagnostics
± Malfunction Indicator Lamp (Service Engine Soon
lamp)
± Data Link Connector (DLC)
± Data Output

Transmission Control Module

Alternator Gain Control
PCM Service Precautions
The PCM is designed to withstand normal current draws
associated with vehicle operation. Avoid overloading any
circuit. When testing for opens and shorts, do not ground
or apply voltage to any of the PCM's circuits unless
instructed to do so. These circuits should only be tested
Tech-2. The PCM should remain connected to the PCM
or to a recommended breakout box.
Reprogramming The PCM
The Trooper allow reprogramming of the PCM without
removing it from the vehicle . This provides a flexible and
cost-effective method of making changes in software
calibrations.
The service programming system (SPS) will not allow
incorrect software programming or incorrect calibration
changes.
Refer to the UBS 98model year Immobilizer Workshop
Manual.
Throttle Position (TP) Sensor
The throttle position (TP) sensor is a potentiometer
connected to the throttle shaft on the throttle body. The
PCM monitors the voltage on the signal line and
calculates throttle position. As the throttle valve angle is
changed (accelerator pedal moved), the TP sensor signal
also changes. At a closed throttle position, the output of

SERVICE INFORMATION 00 Ð 5
Idling improperly adjusted Adjust the idling Idling system
Checkpoint Possible cause Correction
Defective fast idling speed control device Repair or replace the fast idling
speed control device Fast idling speed
control device
Accelerator control system improperly
adjustedAdjust the accelerator control
system Accelerator control
system
2. UNSTABLE IDLING
4. QUICK-ON START SYSTEM (QOS III)
PREPARATION
1. Disconnect the thermoswitch connector.
2. Determine whether or not the glow plugs are receiving power.
a) Make sure that the starter switch is "OFF"
b) Connect a voltmeter between one of the glow plugs and the cylinder wall.
c) Move the starter switch to the "ON" position.
The voltmeter needle will show the souse voltage (12V) if the glow plugs are receiving power.
If the voltmeter needle does not move, the glow plugs are not receiving power.
3. Perform the troubleshooting procedure.
1.
2.
3.Replace the fusible link wire
Replace the indicator light fuse
Replace the indicator light bulb Glow plug indicator
light does not turn
on.Defective Fusible link wire
Broken indicator light fuse
Defective indicator light bulb
1.
2.
3.
4.Replace the fusible link wire
Replace or Repair glow plug relay
connector
Replace or Repair glow plug
connector
Replace or Repair quick-on start
timer connector Preheating system
does not workDefective Fusible link wire shorted
Defective glow plug relay connector
Defective glow plug connector
Defective quick-on start timer connector
1.
2.
3.Replace thermo sensor or repair
wiring harness.
Replace glow plug
Replace timer unit Preheating time to
long or to shortDefective thermo sensor include
defective wiring harness
Defective glow plug
Defective timer unit

SERVICE INFORMATION 00 Ð 11
8. DARK EXHAUST SMOKE
Checkpoint Possible cause Correction
Air cleaner Clogged air cleaner element Clean or replace the air cleaner
element
Injection nozzle Injection nozzle injection starting pressure
too low
Improper spray conditionAdjust or replace the injection
nozzle
Fuel injection timing Fuel injection timing improperly adjusted Adjust the fuel injection timing
Injection pump Defective Delivery valve resulting is fuel
drippage after fuel injectionReplace the delivery valve
Excessive injection volume Adjust the injection volume
9. OIL PRESSURE DOES NOT RISE
Checkpoint Possible cause Correction
Engine oil Improper viscosity engine oil. Insufficient
engine oilReplace the engine oil
Correct the engine oil volume
Oil pressure gauge
or unit
Oil pressure indicator
lightDefective oil pressure gauge or unit
Defective indicator lightRepair or replace the oil pressure
gauge or unit
Replace the indicator light
Oil filter Clogged oil filter element Replace the oil filter element or the
oil filter cartridge
Relief valve and by-
pass valveRelief valve sticking and/or weak by-pass
valve springReplace the relief valve and/or the
by-pass valve spring
Oil pump Clogged oil pump strainer Clean the oil pump strainer
Worn oil pump related parts Replace the oil pump related parts
Rocker arm shaft Worn rocker arm bushing Replace the rocker arm bushing
Camshaft Worn camshaft and camshaft bearing Replace the camshaft and the
camshaft bearing
Crankshaft and
bearingsWorn crankshaft and bearings Replace the crankshaft and/or the
bearings

SERVICE INFORMATION 00 Ð 17
MAGNETIC SWITCH DOES NOT OPERATE THOUGH
STARTER SWITCH IS TURNED TO “START (ST)”
CHECK IF VOLTAGE IS PRESENT AT MAGNETIC
SWITCH TERMINAL “S” WHEN STARTER SWITCH
IS TURNED TO “START (ST)”
YESNO
CHECK IF INDICATOR LAMP ON
METER COMES ON NORMALLY
CHECK CONTINUITY
STARTER SWITCH AND
MAGNETIC SWITCH
TERMINAL “S”DISCONNECTION OR
FAULTY CONNECTION
BETWEEN BATTERY
AND STARTER SWITCH
YESNO
CHECK GROUND CABLE
YESNO
PINION
SLIDING
PART DOES
NOT MOVEMAGNETIC SWITCH
OR COIL IS
DISCONNECTED
OR BURNED OUT
REPAIR
REPAIR OR REPLACE STARTER
REPAIR
CHECK STARTER
RELAYFAULTY CONNECTION
OR STARTER SWITCH
CHECK CLUTCH
START SWITCHREPLACE STARTER
SWITCH
OR

00 Ð 30 SERVICE INFORMATION
Fuel Filter Water Draining Procedure
The indicator light will come on when the water level in the
water separator exceeds the specified level.
Drain the water and foreign material from the water separa-
tor with the following procedure.
1. Find a safe place to park the vehicle.
2. Open the engine hood and place a container (Approxi-
mately 0.2 liter capacity) at the end of the vinyl hose
beneath the drain plug on the separator.
3. Loosen the drain plug by turning it counterclockwise
(Approximately 5 turns) and operate the priming pump
up and down about 10 times until water is drained
approximately 0.1 liter.
4. After draining, securely tighten the drain plug by turn-
ing it clockwise and operate the priming pump manu-
ally up and down several times.
5. After starting the engine, check to see that there is no
fuel leak from the drain plug.
Also check to see that the fuel filter water indicator light
has turned off.
If water separator requires frequent draining, have the
fuel tank drained for removal of water at your Isuzu
Dealer.
Air Bleeding
1. Loosen the bleeder screw on the injection pump over-
flow valve.
2. Operate the priming pump until fuel mixed with foam
flows from the bleeder screw.
3. Tighten the bleeder screw.
4. Operate the priming pump several times and check for
fuel leakage.
COOLING SYSTEM
Coolant Level
Check the coolant level and replenish the radiator reserve
tank as necessary.
If the coolant level falls below the ÒMINÓ line, carefully check
the cooling system for leakage. Then add enough coolant to
bring the level up to the ÒMAXÓ line.
NOTE:
Do not overfill the reserve tank.