ignition ISUZU TROOPER 1998 Service Repair Manual

6E±82
ENGINE DRIVEABILITY AND EMISSIONS
Engine Cranks But Will Not Run

 
StepNo Ye s Value(s) Action
131. Remove any ignition coil and install a spark tester at
the spark plug end of the coil.
2. Observe the tester while the engine is cranking.
Was a crisp, blue spark observed? Only one or two
sparks followed by no result is considered the same as
ªNo Spark.º
ÐGo to Step 15Go to Step 14
14Replace the ignition coil, and return to Step 13 to test
the remaining coils.
Is the action complete?
ÐVerify repairÐ
15Repeat Step 13 for each coil. Remove only one coil at a
time, and reinstall each coil on its spark plug after
testing, but do not refasten coils with screws at this
time.
After all coils have passed the spark test, does the
engine start?
Ð
Refasten all
coils with
their screws
Go to Step 16
161. Remove the spark plugs from all cylinders.
2. Visually inspect the spark plug electrodes.
3. Replace any spark plugs with loose or missing
electrodes or cracked insulators.
Did your inspection reveal any spark plugs exhibiting
excessive fouling?
Ð
Correct the
fouling
condition
Go to Step 17
17Refer to Engine Mechanical Diagnosis to diagnose the
following conditions:

Faulty or incorrect camshaft drive belts

Leaking or sticky valves or rings

Excessive valve deposits

Loose or worn rocker arms

Weak valve springs

Incorrect valve timing

Leaking head gasket
Is the action complete?
ÐVerify repairGo to Step 19
18Observe the ªEngine Speedº data display on the scan
tool while cranking the engine.
Is the engine RPM indicated? (If the scan tool is
normally powered from the cigarette lighter socket, and
if the scan tool display goes blank while cranking the
engine, it will be necessary to power the scan tool
directly from the vehicle battery.)
ÐGo to Step 19Go to Step 28
191. Disconnect the 7-pin gray connector at the rear of
the air filter beneath the point where the air duct
attaches to the MAF sensor.
2. Ignition ªON.º
3. Using a test light connected to ground, probe the
ignition terminal at the PCM (female) side of the
7-pin connector.
Is the test light ªON?º
ÐGo to Step 20Go to Step 26

6E±83 ENGINE DRIVEABILITY AND EMISSIONS
Engine Cranks But Will Not Run

 
StepNo Ye s Value(s) Action
201. At the PCM (female) side of the connector, connect
a test light between the ignition + terminal and one
of the injector driver circuits at the same connector.
2. Ignition ªON.º
3. Observe the test light, and repeat the test for each
injector driver circuit.
Did the test light stay on when checking any of the 6
injector driver circuits?
ÐGo to Step 21Go to Step 23
211. Ignition ªOFF,º disconnect the PCM.
2. Ignition ªON,º observe the test light.
Is the test light ªON?º
ÐGo to Step 22Go to Step 27
22Locate and repair the short to ground in the injector
driver circuit.
Is the action complete?
ÐVerify repairÐ
231. Using the same test location as in step 20, connect
a test light between the ignition terminal and one of
the driver circuits.
2. Crank the engine and observe the test light.
3. Repeat for each injector driver circuit.
Did the light blink during the test for each circuit?
ÐGo to Step 25Go to Step 24
24Check for an open injector driver circuit.
Was a problem found?
ÐVerify repairGo to Step 27
251. At the injector (male) side of the gray connector,
connect an ohmmeter between the ignition pin and
one of the driver circuit pins.
2. Check for continuity in the circuit.
3. Repeat for each injector circuit. The readings
should be approximately equal to the specified
value for injector resistance.
Was a problem found?
12.5 ohmsVerify repairGo to Step 8
26Repair the ignition feed circuit.
Is the action complete?
ÐVerify repairÐ
27Replace the PCM.
IMPORTANT:The replacement PCM must be
programmed. Refer to
UBS 98model year Immobilizer
Workshop Manual.
Is the action complete?ÐVerify repairÐ
281. Raise the vehicle and disconnect the CKP sensor
harness.
2. Ignition ªON.º
3. With a test light to ground, probe the harness
ignition feed terminal.
Did the light illuminate?
ÐGo to Step 30Go to Step 29
29Check the ignition feed wire between the sensor and
the PCM for a short to ground or open circuit.
Is the action complete?
ÐVerify repairÐ

6E±84
ENGINE DRIVEABILITY AND EMISSIONS
Engine Cranks But Will Not Run

 
StepNo Ye s Value(s) Action
301. Ignition ªON.º
2. At the CKP harness connector, connect a test light
between the ignition and ground terminals.
Did the light illuminate?
ÐGo to Step 32Go to Step 31
31Check the sensor ground circuit for an open or short to
voltage.
Is the action complete?
ÐVerify repairÐ
32Check the signal circuit between the sensor and the
PCM for a short to ground, short to voltage, or an open.
Was a problem found?
ÐVerify repairGo to Step 33
33Replace the CKP sensor.
Is the action complete?
ÐVerify repairGo to Step 27

6E±85 ENGINE DRIVEABILITY AND EMISSIONS
Fuel System Electrical Test
D06RW101
Circuit Description
When the ignition switch is first turned ªON,º the
powertrain control module (PCM) energizes the fuel
pump relay which applies power to the in-tank fuel pump.
The fuel pump relay will remain ªONº as long as the
engine is running or cranking and the PCM is receiving
58X crankshaft position pulses. If no 58X crankshaft
position pulses are present, the PCM de-energizes the
fuel pump relay within 2 seconds after the ignition is
turned ªONº or the engine is stopped.
The fuel pump delivers fuel to the fuel rail and injectors,
then to the fuel pressure regulator. The fuel pressure
regulator controls fuel pressure by allowing excess fuel to
be returned to the fuel tank. With the engine stopped and
ignition ªON,º the fuel pump can be turned ªONº by using a
command by Tech 2.
Diagnostic Aids
An intermittent may be caused by a poor connection,
rubbed-through wire insulation, or a wire broken inside
the insulation. Check for the following items:

Poor connection or damaged harness ± Inspect the
PCM harness and connectors 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.
2. If the fuel pump is operating but incorrect pressure is
noted, the fuel pump wiring is OK and the ªFuel
System Pressure Testº chart should be used for
diagnosis.

6E±86
ENGINE DRIVEABILITY AND EMISSIONS
CAUTION: To reduce the risk of fire and personal
injury:

It is necessary to relieve fuel system pressure
before connecting a fuel pressure gauge. Refer to
Fuel Pressure Relief Procedure, below.

A small amount of fuel may be released when
disconnecting the fuel lines. Cover fuel line
fittings with a shop towel before disconnecting, to
catch any fuel that may leak out. Place the towel in
an approved container when the disconnect is
completed.Fuel Pressure Relief Procedure
1. Remove the fuel cap.
2. Remove the fuel pump relay from the underhood
relay center.
3. Start the engine and allow it to stall.
4. Crank the engine for an additional 3 seconds.
Fuel Gauge Installation
1. Remove the shoulder fitting cap.
2. Install fuel gauge 5-8840-0378-0 to the fuel feed line
located in front of and above the right side valve train
cover .
3. Reinstall the fuel pump relay.
Fuel System Electrical Test

StepActionValue(s)Ye sNo
1Was the ªOn-Board Diagnostic (OBD) System Checkº
performed?
ÐGo to Step 2
Go to OBD
System
Check
21. Read the ªCautionº above.
2. Relieve the fuel system pressure and install the fuel
pump pressure gauge to the test fitting.
3. Use Tech 2 to command the fuel pump ªON.º
Is there an immediate pressure build-up which
indicates the pump is running?
ÐGo to Step 3Go to Step 4
31. Verify that the pump is not running by removing the
fuel filler cap and listening.
2. Command the pump ªONº with Tech 2.
Did the pump turn ªOFFº after 2 seconds?
Ð
Test
completed
Go to Step 12
41. Ignition ªOFF.º
2. Remove the fuel pump relay.
3. Using a test light connected to ground, probe the
battery feed to the relay.
Did the light illuminate?
ÐGo to Step 6Go to Step 5
5Repair short or open battery feed to fuel pump relay.
Is the action complete?
ÐVerify repairÐ
61. Connect a test light between the two wires that
connect to the fuel pump relay pull-in coil.
2. Ignition ªON.º
Did the test light illuminate for 2 seconds and then turn
off?
ÐGo to Step 12Go to Step 7
71. With a test light connected to battery (±), probe the
fuel pump relay connector at the wire which runs
from the relay pull-in coil to the PCM.
2. Ignition ªON.º
Did the test light illuminate for 2 seconds and then turn
off?
ÐGo to Step 8Go to Step 9
8Locate and repair open in the fuel pump relay ground
circuit.
Is the action complete?
ÐVerify repairÐ

6E±88
ENGINE DRIVEABILITY AND EMISSIONS
Fuel System Diagnosis
140RW020
Legend
(1) Fuel Filler Cap
(2) Fuel Tank
(3) Rollover Valve
(4) Fuel Pump and Sender Assembly
(5) Fuel Filter
(6) Fuel Rail Right
(7) Right Bank(8) Fuel Rail Left
(9) Left Bank
(10) Fuel Pressure Control Valve
(11) Common Chamber
(12) Duty Solenoid Valve
(13) Throttle Valve
(14) Canister
(15) Evapo Shut Off Valve
Circuit Description
When the ignition switch is turned ªON,º the powertrain
control module (PCM) will turn ªONº the in-tank fuel
pump. The in-tank fuel pump will remain ªONº as long as
the engine is cranking or running and the PCM is receiving
58X crankshaft position pulses. If there are no 58X
crankshaft position pulses, the PCM will turn the in-tank
fuel pump ªOFFº 2 seconds after the ignition switch is
turned ªONº or 2 seconds after the engine stops running.
The in-tank fuel pump is an electric pump within an
integral reservoir. The in-tank fuel pump supplies fuel
through an in-line fuel filter to the fuel rail assembly. The
fuel pump is designed to provide fuel at a pressure above
the pressure needed by the fuel injectors. A fuel pressure
regulator, attached to the fuel rail, keeps the fuel available
to the fuel injectors at a regulated pressure. Unused fuel
is returned to the fuel tank by a separate fuel return line.
Test Description
Number(s) below refer to the step number(s) on the
Diagnostic Chart.
2. Connect the fuel pressure gauge to the fuel feed line
as shown in the fuel system illustration. Wrap a
shop towel around the fuel pressure connection in
order to absorb any fuel leakage that may occur
when installing the fuel pressure gauge. With the
ignition switch ªONº and the fuel pump running, the
fuel pressure indicated by the fuel pressure gauge
should be 333-376 kPa (48-55 psi). This pressure
is controlled by the amount of pressure the spring
inside the fuel pressure regulator can provide.
3. A fuel system that cannot maintain a constant fuel
pressure has a leak in one or more of the following
areas:

The fuel pump check valve.

The fuel pump flex line.

6E±90
ENGINE DRIVEABILITY AND EMISSIONS
Fuel System Diagnosis

StepActionValue(s)Ye sNo
1Was the ªOn-Board Diagnostic (OBD) System Checkº
performed?
ÐGo to Step 2
Go to OBD
System
Check
21. Turn the ignition ªOFF.º
2. Turn the air conditioning system ªOFF.º
3. Relieve fuel system pressure and install the fuel
pressure gauge.
4. Turn the ignition ªON.º
NOTE: The fuel pump will run for approximately 2
seconds. Use Tech 2 to command the fuel pump ªONº.
5. 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 3Go to Step 17
3NOTE: The fuel pressure will drop when the fuel pump
stops running, then it should stabilize and remain
constant.
Does the fuel pressure indicated by the fuel pressure
gauge remain constant?
ÐGo to Step 4Go to Step 12
41. When the vehicle is at normal operation
temperature, turn the ignition ªONº to build fuel
pressure and observe the measurement on the
gauge.
2. Start the engine and observe the fuel pressure
gauge.
Did the reading drop by the amount specified after the
engine was started?
21-105 kPa
(3-15 psi)
Go to Step 5Go to Step 9
5Is fuel pressure dropping off during acceleration,
cruise, or hard cornering?
ÐGo to Step 6
Check for
improper fuel
6Visually and physically inspect the following items for a
restriction:

The in-pipe fuel filter.

The fuel feed line.
Was a restriction found?
ÐVerify repairGo to Step 7
7Remove the fuel tank and visually and physically
inspect the following items:

The fuel pump strainer for a restriction.

The fuel line for a leak.

Verify that the correct fuel pump is in the vehicle.
Was a problem found in any of these areas?
ÐVerify repairGo to Step 8
8Replace the fuel pump.
Is the action complete?
ÐVerify repairÐ
91. Disconnect the vacuum hose from the fuel pressure
regulator.
2. With the engine idling, apply 12-14 inches of
vacuum to the fuel pressure regulator.
Does the fuel pressure indicated by the fuel pressure
gauge drop by the amount specified?
21-105 kPa
(3-15 psi)
Go to Step 10Go to Step 11

6E±94
ENGINE DRIVEABILITY AND EMISSIONS
Idle Air Control (IAC) System Check

StepActionValue(s)Ye sNo
11. Ignition ªOFF.º
2. Connect the Tech 2.
3. Set the parking brake.
4. Block the wheels.
5. Turn the air conditioning ªOFF.º
6. Idle the engine in Park (A/T) or Neutral (M/T).
7. Operate the IAC test.
8. The engine speed should decrease and increase as
the IAC is cycled.
Does the RPM change?
ÐGo to Step 2Go to Step 3
2RPM should change smoothly.
Does the RPM change within the range specified?700-1500
RPM
ÐGo to Step 3
3Check the IAC passages.
Are the IAC passages OK?
ÐGo to Step 4Go to Step 5
4Clear any obstruction from the IAC passages.
Is the action complete?
ÐVerify repairÐ
5Replace the IAC. Refer to On-Vehicle Service, Idle Air
Control Valve.
Is the action complete?ÐVerify repairÐ

6E±96
ENGINE DRIVEABILITY AND EMISSIONS
Knock Sensor (KS) System Check
(Engine Knock, Poor Performance, or Poor Economy)

StepActionValue(s)Ye sNo
1Is DTC P0325 or P0327 set?
Ð
Go to DTC
P0325 or
DTC P0327
Go to Step 2
2Run the engine at 1500 RPM.
Is there an internal engine knock?
ÐGo to Step 3Go to Step 4
3Repair the mechanical problem.
Is the action complete?
ÐVerify repairÐ
41. Install Tech 2.
2. Turn the ignition ªON.º
3. Cycle through the list until ªKnock Retardº is
displayed.
Is knock retard at the specified value?
0
Go to Step 6Go to Step 7
5Replace the PCM.
IMPORTANT:The replacement PCM must be
programmed. Refer to
UBS 98model year Immobilizer
Workshop Manual.
Is the action complete?ÐVerify repairÐ
61. Start the engine.
2. Monitor the knock retard display on Tech 2 while
changing the throttle setting to place different loads
on the engine.
Is knock retard at the specified value? (Turn the ignition
ªOFF.º)
0
Go to Step 9Go to Step 7
71. At the rear of the engine, behind the rear fuel
injector on the lift side, disconnect the 2-wire knock
sensor harness connector.
2. Attach the positive lead of DVM to B+.
3. On the main harness side of the connector, use the
negative lead of the DVM to probe the connector pin
that is connected to the black wire.
Dose the DVM indicate the specified value?
(Reconnect the knock sensor harness.)
B+Go to Step 9Go to Step 8
8Repair the open black wire ground for the shield which
prevents stray electromagnetic pulses from affecting
the knock signal.
Is the action complete?
ÐVerify repairÐ
91. Reconnect the wire harness.
2. Set a DVM to AC voltage.
3. With the DVM, backprobe the PCM connector at
A2.
4. Tap the engine lift brackprobe with a socket
extension.
Did the DVM show an increase in AC voltage while
tapping on the lift bracket?
ÐSystem OKGo to Step 10
10Replace the knock sensor.
Is the action complete?
ÐVerify repairÐ

6E±98
ENGINE DRIVEABILITY AND EMISSIONS
Exhaust Gas Recirculation (EGR) System Check

StepActionValue(s)Ye sNo
1Check the EGR valve for looseness.
Is the EGR valve Loose?
ÐGo to Step 2Go to Step 3
2Tighten the EGR valve.
Is the action complete?
ÐVerify repairÐ
31. Place the transmission selector in Park or Neutral.
2. Start the engine and idle until warm.
3. Using Tech 2, command EGR ª50% ON.º
Does the engine idle rough and lose RPMs?
Ð
EGR system
working
properly. No
problem
found.
Go to Step 4
41. Engine ªOFF.º
2. Ignition ªON.º
3. Using a test light to ground, check the EGR harness
between the EGR valve and the ignition feed.
Does the test light illuminate?
ÐGo to Step 6Go to Step 5
5Repair the EGR harness ignition feed.
Was the problem corrected?
ÐVerify repairGo to Step 6
61. Remove the EGR valve.
2. Visually and physically inspect the EGR valve
pintle, valve passages and adapter for excessive
deposits, obstructions or any restrictions.
Does the EGR valve have excessive deposits,
obstructions or any restrictions?
ÐGo to Step 7Go to Step 8
7Clean or replace EGR system components as
necessary.
Was the problem corrected?
ÐVerify repairGo to Step 8
81. Ground the EGR valve metal case to battery (±).
2. Using Tech 2, command EGR ªONº and observe the
EGR valve pintle for movement.
Does the EGR valve pintle move according to
command?
ÐGo to Step 9
Go to DTC
P1406 chart
91. Remove the EGR inlet and outlet pipes from the
intake and exhaust manifolds.
2. Visually and physically inspect manifold EGR ports
and EGR inlet and outlet pipes for blockage or
restriction caused by excessive deposits or other
damage.
Do the manifold EGR ports or inlet and outlet pipes
have excessive deposits, obstructions, or any
restrictions?
ÐGo to Step 10
EGR system
working
properly. No
problem
found.
10Clean or replace EGR system components as
necessary.
Is the action complete?
ÐVerify repairÐ