2002 ISUZU AXIOM check engine

6E±548
6VE1 3.5L 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 for 4WD
and on the extension cover for 2WD. 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.
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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 for 4WD and on the extension cover for 2WD.
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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.).
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3. Connect the VSS electrical connector.
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4. Check the transfer case oil level. Add fluid if
necessary.
5. Connect the negative battery cable.

6E±551
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Accelerator Position Sensor
Replacement
CAUTION: R e m o v e t h e Accelerator (A) pedal
assembly as a unit to have it serviced. Do not remove
the Accelerator Position (AP) sensor on the A pedal.
If the AP sensor is removed for emergency cause,
refer to following items as necessary.
Removal Procedure
1. Disconnect the negative battery cable.
2. Disconnect the electrical harness from the AP sensor.
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Legend
(1) AP Sensor
(2) A Pedal Assembly
3. Remove the AP sensor.
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Legend
(1) AP Sensor
(2) AP Screw
Installation Procedure
1. Install the accelerator position (AP) sensor to bolts
with accelerator (A) pedal.
2. Connect the connector to AP sensor.
3. Install the negative battery cable.
Accelerator Position Sensor
Adjustment
AP sensor is controled three maltiple control system, and
adjust the idle position and WOT position are between A
and B for AP sensor 1, AP sensor 2, and AP sensor 3.
Refer to
ªHow to adjust for AP sensorº.
Removal Procedure
1. Disconnect the negative battery cable.
2. Disconnect the electrical harness from the AP sensor.
How To Adjust For AP Sensor
1. Connect the Tech 2 to DLC on vehicle.
2. Ignition ªON,º engine ªOFF.º.
3. Display the APS date list. Check the following item for
AP position (%).
AP position (%)
Idle position AWOT position B
APS113%87 + 2%
APS287 + 2%13 + 2%
APS387 + 1%34 + 2%
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6E±552
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
4. If the problem was found, adjust as necessary.
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Fuel Filler 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.
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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 Procedure
1. Disconnect the negative battery cable.
2. Remove the fuel filler cap.
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3. Disconnect the fuel hose from the fuel filter on the
engine side.
4. Disconnect the fuel hose from the fuel filter on the fuel
tank side.
5. Remove the bolt on the fuel filter holder.
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Legend
(1) Fuel Hose
(2) Fuel Filter Fixing Bolt
(3) Fuel Filter
6. Remove the fuel filter.

6E±554
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Fuel Injectors
Removal Procedure
NOTE: If the fuel injectors are leaking, the engine oil may
be contaminated with fuel. Check the oil for signs of
contamination and change the oil and the filter if
necessary.
NOTE: Use care in removing the fuel injectors in order to
prevent damage to the fuel injector electrical connector
pins or the fuel injector nozzles. The fuel injector is an
electrical component and should not be immersed in any
type of cleaner as this may damage the fuel injector.
IMPORTANT:Fuel injectors are serviced as a complete
assembly only.
1. Disconnect the negative battery cable.
2. Remove the common chamber. Refer to
Common
Chamber in Engine Mechanical
section.
3. Remove the fuel rail. Refer to
Fuel Rail section.
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4. Remove the injector retainer clip.
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5. Remove the fuel injector assembly.
6. Remove the O-ring from the fuel injector.
7. Remove the O-ring backup from the fuel injector .
Inspection Procedure
1. Inspect the O-rings for cracks or leaks.
2. Replace worn or damaged O-rings.
3. Lubricate the new O-rings with engine oil before
installation.
Installation Procedure
1. Install the O-ring backup on the fuel injector.
2. Install the new O-ring on the fuel injector.
3. Install the fuel injector on the fuel rail.
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4. Use new fuel injector retainer clips to retain the fuel
injector to the fuel rail.
5. Coat the end of the fuel injector with gasoline.

6E±563
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
3. Slide the out of EVAP canister vent solenoid from
mounting bracket.
014RW135
Inspection Procedure
1. Check for cracks or leaks.
2. Energize the solenoid and try to blow through it. The
solenoid should not allow passage of air when
energized. (J 35616 Connector Test Kit can be used
to easily attach jumper wires from the battery to the
solenoid).
Installation Procedure
1. Slide the into EVAP canister vent solenoid into the
mounting bracket.
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2. Connect the connector and hose.
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3. Connect the negative battery cable.
Fuel Tank Pressure
(Vapor Pressure) Sensor
Removal Procedure
1. Remove the fuel pump assembly. Refer to Fuel Tank
In Fuel Pump
.
2. Carefully pry the fuel tank pressure sensor out of the
top of the fuel pump assembly.
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Inspection Procedure
1. Inspect the vapor pressure sensor for cracks in the
housing and corrosion on the electrical terminals.
2. Inspect the rubber grommet for tears and signs of rot.

6E±566
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Positive Crankcase Ventilation
(PCV) Valve
Removal Procedure
1. Remove the vacuum hose at the PCV valve.

Slide the clamp back to release the hose.
2. Pull the PCV valve from the rubber grommet in the
right valve cover.
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Inspection Procedure
Before inspecting the PCV valve, make sure that the
hoses are connected properly and are in good condition.
Also check that the oil pan and rocker cover gaskets are
sealing properly.
PCV Valve
1. Run the engine at normal operating temperature.
2. Disconnect the valve from the rocker cover.
RESULT: A hissing noise should be heard from the
valve. If no noise is heard, the PCV valve or hose is
plugged.
3. Remove the PCV valve from the engine.
a. Blow air into the rocker cover side of the valve.
RESULT: Air should pass freely.
b. Blow air into the air cleaner side of the valve.
RESULT: Air should not pass through the valve.
4. Re-install the PCV valve and remove the oil filler cap.
RESULT: A small vacuum should be felt at the oil filler
hole.
Installation Procedure
1. Push the PCV valve into the rubber grommet in the
left valve cover.2. Install the vacuum hose on the PCV valve and secure
the vacuum hose with the clamp.
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Wiring and Connectors
Wiring Harness Service
The control module harness electrically connects the
control module 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
section 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.

6E±575
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Powertrain Control Module (PCM)
The powertrain control module (PCM) is located in the
passenger compartment below the center console. The
PCM controls the following:

Fuel metering system.

Transmission shifting (automatic transmission only).

Ignition timing.

On-board diagnostics for powertrain functions.
The PCM constantly observes the information from
various sensors. The PCM controls the systems that
affect vehicle performance. The PCM performs the
diagnostic function of the system. It can recognize
operational problems, alert the driver through the MIL
(Check Engine lamp), and store diagnostic trouble codes
(DTCs). DTCs identify the problem areas to aid the
technician in making repairs.
PCM Function
The PCM supplies either 5 or 12 volts to power various
sensors or switches. The power is supplied through
resistances in the PCM which are so high in value that a
test light will not light when connected to the circuit. In
some cases, even an ordinary shop voltmeter will not give
an accurate reading because its resistance is too low.
Therefore, a digital voltmeter with at least 10 megohms
input impedance is required to ensure accurate voltage
readings. Tool J 39200 meets this requirement. The PCM
controls output circuits such as the injectors, fan relays,
etc., by controlling the ground or the power feed circuit
through transistors or through either of the following two
devices:

Output Driver Module (ODM)

Quad Driver Module (QDM)
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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

ION sensing module

Automatic transmission shift functions

Cruise control

Evaporative emission (EVAP) purge

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

Acceleration Position
Outputs ± Systems Controlled

EVAP Canister Purge

Exhaust Gas Recirculation (EGR)

Ignition Control

Fuel Control

ION Sensing Module

Electric Fuel Pump

Air Conditioning

6E±579
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
The PCM monitors signals from several sensors in order
to determine the fuel needs of the engine. Fuel is
delivered under one of several conditions called ªmodes.º
All modes are controlled by the PCM.
Fuel Pressure Regulator
The fuel pressure regulator is a diaphragm-operated
relief valve mounted on the fuel rail with fuel pump
pressure on one side and manifold pressure on the other
side. The fuel pressure regulator maintains the fuel
pressure available to the injector at three times
barometric pressure adjusted for engine load. It may be
serviced separtely.
If the pressure is too low, poor performance and a DTC
P0131, DTC P0151,DTC P0171 or DTC P1171 will be the
result. If the pressure is too high, excessive odor and/or a
DTC P0132, DTC P0152,DTC P0172 will be the result.
Refer to
Fuel System Diagnosis for information on
diagnosing fuel pressure conditions.
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Fuel Pump Electrical Circuit
When the key is first turned ªON,º the PCM energizes the
fuel pump relay for two seconds to build up the fuel
pressure quickly. If the engine is not started within two
seconds, the PCM shuts the fuel pump off and waits until
the engine is cranked. When the engine is cranked and
the 58 X crankshaft position signal has been detected by
the PCM, the PCM supplies 12 volts to the fuel pump relay
to energize the electric in-tank fuel pump.
An inoperative fuel pump will cause a ªno-startº condition.
A fuel pump which does not provide enough pressure will
result in poor performance.
Fuel Rail
The fuel rail is mounted to the top of the engine and
distributes fuel to the individual injectors. Fuel is
delivered to the fuel inlet tube of the fuel rail by the fuel
lines. The fuel goes through the fuel rail to the fuel
pressure regulator. The fuel pressure regulator maintains
a constant fuel pressure at the injectors. Remaining fuel
is then returned to the fuel tank.
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Run Mode
The run mode has the following two conditions:

Open loop

Closed loop
When the engine is first started the system is in ªopen
loopº operation. In ªopen loop,º the PCM ignores the
signal from the heated oxygen sensor (HO2S). It
calculates the air/fuel ratio based on inputs from the TP,
ECT, and MAF sensors.
The system remains in ªopen loopº until the following
conditions are met:

The HO2S has a varying voltage output showing that
it is hot enough to operate properly (this depends on
temperature).

The ECT has reached a specified temperature.

A specific amount of time has elapsed since starting
the engine.

Engine speed has been greater than a specified RPM
since start-up.
The specific values for the above conditions vary with
different engines and are stored in the programmable
read only memory (PROM). When these conditions are
met, the system enters ªclosed loopº operation. In
ªclosed loop,º the PCM calculates the air/fuel ratio
(injector on-time) based on the signal from the HO2S.
This allows the air/fuel ratio to stay very close to 14.7:1.
Starting Mode
When the ignition is first turned ªON,º the PCM energizes
the fuel pump relay for two seconds to allow the fuel pump
to build up pressure. The PCM then checks the engine
coolant temperature (ECT) sensor and the throttle
position (TP) sensor to determine the proper air/fuel ratio
for starting.
The PCM controls the amount of fuel delivered in the
starting mode by adjusting how long the fuel injectors are
energized by pulsing the injectors for very short times.