2002 ISUZU AXIOM ignition

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.
101RY00006
Legend
(1) AP Sensor
(2) A Pedal Assembly
3. Remove the AP sensor.
101RY00009
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%
060RY00305

6E±560
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Electronic Ignition System
Removal Procedure
1. Disconnect the negative battery cable.
2. Disconnect the ignition coil connector at the ignition
coil assemblies.
3. Remove the two screws that secure the ignition coil
assemblies to the rocker cover.
060RY022
Legend
(1) Ignition Coil Connectors
(2) Bolts
(3) Ignition Coil Assemblies
4. Remove the ignition coil assemblies and the spark
plug boot from the spark plug.

Twist the ignition coil assemblies while pulling it
straight up.
5. Use the appropriate spark plug socket in order to
remove the spark plug from the engine.
Installation Procedure
NOTE: The plug must thread smoothly into the cylinder
head and be fully seated. Use a thread chaser if
necessary to clean the threads in the cylinder head.
Cross-threading or failure to fully seat the spark plug can
cause plug overheating, exhaust blow-by gases, or
thread damage. Do not overtighten the spark plugs. Over
tightening can cause aluminum threads to strip.
1. Install the spark plug in the engine. Use the
appropriate spark plug socket.
Tighten

Tighten the spark plug to 18 N´m (13 lb ft.).
2. Install the ignition coil assemblies and spark plug boot
over the spark plug.CAUTION: Ignition coil assembly #6 is different
from ignition coil assembly #1 to #5. Ignition coil
assemblies #6 is short type. Be careful it when
installing ignition coil assembly of #6.
060RY00002
Legend
(1) Long Type Ignition Coil Assemblies (#1 ~ #5)
(2) Short Type Ignition Coil Assembly (#6)
3. Install ignition coil assemblies and tighten the fixing
bolts to the specified torque.
Torque: 4 N´m (35.4 Ib in)
060RY022
Legend
(1) Ignition Coil Connectors
(2) Bolts
(3) Ignition Coil Assemblies
4. Connect the ignition coil connector at the ignition coil
assemblies.
5. Connect the negative battery cable.

6E±572
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
General Description (PCM and
Sensors)
58X Reference PCM Input
The powertrain control module (PCM) uses this signal
from the crankshaft position (CKP) sensor to calculate
engine RPM and crankshaft position at all engine speeds.
The PCM also uses the pulses on this circuit to initiate
injector pulses. If the PCM receives no pulses on this
circuit, DTC P0337 will set. The engine will not start and
run without using the 58X reference signal.
A/C Request Signal
This signal tells the PCM when the A/C mode is selected
at the A/C control head. The PCM uses this to adjust the
idle speed before turning ªONº the A/C clutch. The A/C
compressor will be inoperative if this signal is not
available to the PCM.
Refer to
A/C Clutch Circuit Diagnosis section for A/C
wiring diagrams and diagnosis for the A/C electrical
system.
Crankshaft Position (CKP) Sensor
The crankshaft position (CKP) sensor provides a signal
used by the powertrain control module (PCM) to calculate
the ignition sequence. The CKP sensor initiates the 58X
reference pulses which the PCM uses to calculate RPM
and crankshaft position.
Refer to
Electronic Ignition System section for additional
information.
0013
Engine Coolant Temperature (ECT) Sensor
The engine coolant temperature (ECT) sensor is a
thermistor (a resistor which changes value based on
temperature) mounted in the engine coolant stream. Low
coolant temperature produces a high resistance of
100,000 ohms at ±40
C (±40
F). High temperature
causes a low resistance of 70 ohms at 130
C (266
F).
The PCM supplies a 5-volt signal to the ECT sensor
through resistors in the PCM and measures the voltage.
The signal voltage will be high when the engine is cold and
low when the engine is hot. By measuring the voltage, thePCM calculates the engine coolant temperature. Engine
coolant temperature affects most of the systems that the
PCM controls.
The Tech 2 displays engine coolant temperature in
degrees. After engine start-up, the temperature should
rise steadily to about 85
C (185
F). It then stabilizes
when the thermostat opens. If the engine has not been
run for several hours (overnight), the engine coolant
temperature and intake air temperature displays should
be close to each other. A hard fault in the engine coolant
sensor circuit will set DTC P0177 or DTC P0118. An
intermittent fault will set a DTC P1114 or P1115.
0016
Electrically Erasable Programmable Read
Only Memory (EEPROM)
The electrically erasable programmable read only
memory (EEPROM) is a permanent memory chip that is
physically soldered within the PCM. The EEPROM
contains the program and the calibration information that
the PCM needs to control powertrain operation.
Unlike the PROM used in past applications, the EEPROM
is not replaceable. If the PCM is replaced, the new PCM
will need to be programmed. Equipment containing the
correct program and calibration for the vehicle is required
to program the PCM.
Fuel Control Heated Oxygen Sensors
The fuel control heated oxygen sensors (Bank 1 HO2S 1
and Bank 2 HO2S 1) are mounted in the exhaust stream
where they can monitor the oxygen content of the exhaust
gas. The oxygen present in the exhaust gas reacts with
the sensor to produce a voltage output. This voltage
should constantly fluctuate from approximately 100 mV to
900 mV. The heated oxygen sensor voltage can be
monitored with a Tech 2. By monitoring the voltage output
of the oxygen sensor, the PCM calculates the pulse width
command for the injectors to produce the proper
combustion chamber mixture.

Low HO2S voltage is a lean mixture which will result in
a rich command to compensate.

High HO2S voltage is a rich mixture which will result in
a lean command to compensate.

6E±573
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
An open Bank 1 HO2S 1 signal circuit will set a DTC
P0134 and the Tech 2 will display a constant voltage
between 400-500 mV. A constant voltage below 300 mV
in the sensor circuit (circuit grounded) will set DTC
P0131. A constant voltage above 800 mV in the circuit will
set DTC P0132. Faults in the Bank 2 HO2S 1 signal
circuit will cause DTC 0154 (open circuit), DTC P0151
(grounded circuit), or DTC P0152 (signal voltage high) to
set. A fault in the Bank 1 HO2S 1 heater circuit will cause
DTC P0135 to set. A fault in the Bank 2 HO2S 1 heater
circuit will cause DTC P0155 to set. The PCM can also
detect HO2S response problems. If the response time of
an HO2S is determined to be too slow, the PCM will store
a DTC that indicates degraded HO2S performance.
060RY00127
Catalyst Monitor Heated Oxygen Sensors
Three-way catalytic converters are used to control
emissions of hydrocarbons (HC), carbon monoxide (CO),
and oxides of nitrogen (NOx). The catalyst within the
converters promotes a chemical reaction. This reaction
oxidizes the HC and CO present in the exhaust gas and
converts them into harmless water vapor and carbon
dioxide. The catalyst also reduces NOx by converting it to
nitrogen. The PCM can monitor this process using the
Bank 1 HO2S 2 and the Bank 2 HO2S 2 heated oxygen
sensors. The Bank 1 HO2S 1 and the Bank 2 HO2S 1
sensors produce an output signal which indicates the
amount of oxygen present in the exhaust gas entering the
three-way catalytic converter. The Bank 1 HO2S 2 and
the Bank 2 HO2S 2 sensors produce an output signal
which indicates the oxygen storage capacity of the
catalyst. This indicates the catalyst's ability to efficiently
convert exhaust gases. If the catalyst is operating
efficiently, the Bank 1 HO2S 1 and the Bank 2 HO2S 1
signals will be more active than the signals produced by
the Bank 1 HO2S 2 and the Bank 2 HO2S 2 sensors.
The catalyst monitor sensors operate the same as the
fuel control sensors. The Bank 1 HO2S 2 and the Bank 2
HO2S 2 sensors' main function is catalyst monitoring, but
they also have a limited role in fuel control. If a sensor
output indicates a voltage either above or below the 450
mV bias voltage for an extended period of time, the PCMwill make a slight adjustment to fuel trim to ensure that
fuel delivery is correct for catalyst monitoring.
A problem with the Bank 1 HO2S 2 signal circuit will set
DTC P0137, P0138, or P0140, depending on the specific
condition. A problem with the Bank 2 HO2S 2 signal
circuit will set DTC P0157, P0158, or P0160, depending
on the specific condition. A fault in the heated oxygen
sensor heater element or its ignition feed or ground will
result in lower sensor response. This may cause
incorrect catalyst monitor diagnostic results.
TS24067
TS23365A
Legend
(1) Bank 1 Sensor 1 (Fuel Control)
(2) Catalytic Converter
(3) Bank 1 Sensor 2 (Catalyst Monitor)
(4) Bank 2 Sensor 1 (Fuel Control)
(5) Bank 2 Sensor 2 (Catalyst Monitor)
Intake Air Temperature (IAT) Sensor
The intake air temperature (IAT) sensor is a thermistor
which changes its resistance based on the temperature of
air entering the engine. Low temperature produces a high

6E±574
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
resistance of 100,000 ohms at ±40
C (±40
F). High
temperature causes low resistance of 70 ohms at 130
C
(266
F) . The PCM supplies a 5-volt signal to the sensor
through a resistor in the PCM and monitors the signal
voltage. The voltage will be high when the incoming air is
cold. The voltage will be low when the incoming air is hot.
By measuring the voltage, the PCM calculates the
incoming air temperature. The IAT sensor signal is used
to adjust spark timing according to the incoming air
density.
The Tech 2 displays the temperature of the air entering
the engine. The temperature should read close to the
ambient air temperature when the engine is cold and rise
as underhood temperature increases. If the engine has
not been run for several hours (overnight), the IAT sensor
temperature and engine coolant temperature should read
close to each other. A fault in the IAT sensor circuit will set
DTC P0112 or DTC P0113.
Linear Exhaust Gas Recirculation (EGR)
Control
The PCM monitors the exhaust gas recirculation (EGR)
actual position and adjusts the pintle position accordingly.
The PCM uses information from the following sensors to
control the pintle position:

Engine coolant temperature (ECT) sensor.

Throttle position (TP) sensor.

Mass air flow (MAF) sensor.
Mass Air Flow (MAF) Sensor
The mass air flow (MAF) sensor measures the difference
between the volume and the quantity of air that enters the
engine. ªVolumeº means the size of the space to be filled.
ªQuantityº means the number of air molecules that will fit
into the space. This information is important to the PCM
because heavier, denser air will hold more fuel than
lighter, thinner air. The PCM adjusts the air/fuel ratio as
needed depending on the MAF value. The Tech 2 reads
the MAF value and displays it in terms of grams per
second (gm/s). At idle, the Tech 2 should read between
4-7 gm/s on a fully warmed up engine. Values should
change quickly on acceleration. Values should remain
stable at any given RPM. A failure in the MAF sensor or
circuit will set DTC P0101, DTC P0102, or DTC P0103.
0007
Manifold Absolute Pressure (MAP) Sensor
The manifold absolute pressure (MAP) sensor responds
to changes in intake manifold pressure (vacuum). The
MAP sensor signal voltage to the PCM varies from below
2 volts at idle (high vacuum) to above 4 volts with the
ignition ON, engine not running or at wide-open throttle
(low vacuum).
The MAP sensor is used to determine the following:

Manifold pressure changes while the linear EGR flow
test diagnostic is being run. Refer to
DTC P0401.

Barometric pressure (BARO).
If the PCM detects a voltage that is lower than the
possible range of the MAP sensor, DTC P0107 will be set.
A signal voltage higher than the possible range of the
sensor will set DTC P0108. An intermittent low or high
voltage will set DTC P1107, respectively. The PCM can
detect a shifted MAP sensor. The PCM compares the
MAP sensor signal to a calculated MAP based on throttle
position and various engine load factors. If the PCM
detects a MAP signal that varies excessively above or
below the calculated value, DTC P0106 will set.
055RW004

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)
060RY00068
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±576
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS

Diagnostics
± Malfunction Indicator Lamp
± Data Link Connector (DLC)
± Data Output

Transmission Control Module
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
using digital voltmeter J 39200. The PCM should remain
connected to the PCM or to a recommended breakout
box.
Reprogramming The PCM
Reprogramming of the PCM is done without removing it
from the vehicle . This provides a flexible and
cost-effective method of making changes in software
calibrations.
Refer to the latest Techline information on
reprogramming or flashing procedures.
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
the TP1 sensor is low. As the throttle valve opens, the
output increases so that at wide open throttle (WOT), the
output voltage should be above 92% (Tech 2 Display).
The PCM calculates fuel delivery based on throttle valve
angle (driver demand). A broken or loose TP sensor may
cause intermittent bursts of fuel from an injector and
unstable idle because the PCM thinks the throttle is
moving.
060RY00027
Transmission Fluid Temperature (TFT)
Sensor
The transmission fluid temperature sensor is a thermistor
which changes its resistance based on the temperature of
the transmission fluid. For a complete description of the
TFT sensor, refer to
4L30-E Automatic Transmission
Diagnosis
section.
A failure in the TFT sensor or associated wiring will cause
DTC P0712 or DTC P0713 to set. In this case, engine
coolant temperature will be substituted for the TFT
sensor value and the transmission will operate normally.
Transmission Range Switch (Mode Switch)
IMPORTANT:The vehicle should not be driven with the
transmission range switch disconnected; idle quality will
be affected.
The four inputs from the transmission range switch
indicate to the PCM which position is selected by the
transmission selector lever. This information is used for
ignition timing, EVAP canister purge, EGR operation.
For more information on the transmission on the
transmission range switch, refer to
4L30-E Automatic
Transmission
section.
Vehicle Speed Sensor (VSS)
The PCM determines the speed of the vehicle by
converting a pulsing voltage signal from the vehicle speed
sensor (VSS) into miles per hour. The PCM uses this
signal to operate the cruise control, speedometer, and the
TCC and shift solenoids in the transmission. For more
information on the TCC and shift solenoids, refer to
4L30-E Automatic Transmission section.
0008
Use of Circuit Testing Tools
Do not use a test light to diagnose the powertrain
electrical systems unless specifically instructed by the
diagnostic procedures. Use Connector Test Adapter Kit J
35616 whenever diagnostic procedures call for probing
connectors.

6E±578
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
General Description (Fuel Metering)
Acceleration Mode
The PCM provides extra fuel when it detects a rapid
increase in the throttle position and the air flow.
Battery Voltage Correction Mode
When battery voltage is low, the PCM will compensate for
the weak spark by increasing the following:

The amount of fuel delivered.

The idle RPM.

Ignition dwell time.
Clear Flood Mode
Clear a flooded engine by pushing the accelerator pedal
down all the way. The PCM then de-energizes the fuel
injectors. The PCM holds the fuel injectors de-energized
as long as the throttle remains above 80% and the engine
speed is below 800 RPM. If the throttle position becomes
less than 80%, the PCM again begins to pulse the
injectors ªONº and ªOFF,º allowing fuel into the cylinders.
Deceleration Mode
The PCM reduces the amount of fuel injected when it
detects a decrease in the throttle position and the air flow.
When deceleration is very fast, the PCM may cut off fuel
completely for short periods.
Engine Speed/Vehicle Speed/Fuel Disable
Mode
The PCM monitors engine speed. It turns off the fuel
injectors when the engine speed increases above 6400
RPM. The fuel injectors are turned back on when engine
speed decreases below 6150 RPM.
Fuel Cutoff Mode
No fuel is delivered by the fuel injectors when the ignition
is ªOFF.º This prevents engine run-on. In addition, the
PCM suspends fuel delivery if no reference pulses are
detected (engine not running) to prevent engine flooding.
Fuel Injector
The sequential multiport fuel injection (SFI) fuel injector is
a solenoid-operated device controlled by the PCM. The
PCM energizes the solenoid, which opens a valve to allow
fuel delivery.
The fuel is injected under pressure in a conical spray
pattern at the opening of the intake valve. Excess fuel not
used by the injectors passes through the fuel pressure
regulator before being returned to the fuel tank.
A fuel injector which is stuck partly open will cause a loss
of fuel pressure after engine shut down, causing long
crank times.
014RY00009
Fuel Metering System Components
The fuel metering system is made up of the following
parts:

The fuel injectors.

The throttle body.

The fuel rail.

The fuel pressure regulator.

The PCM.

The crankshaft position (CKP) sensor.

The ION sensing module.

The fuel pump.

The fuel pump relay.
Basic System Operation
The fuel metering system starts with the fuel in the fuel
tank. An electric fuel pump, located in the fuel tank,
pumps fuel to the fuel rail through an in-line fuel filter. The
pump is designed to provide fuel at a pressure above the
pressure needed by the injectors. A fuel pressure
regulator in the fuel rail keeps fuel available to the fuel
injectors at a constant pressure. A return line delivers
unused fuel back to the fuel tank. Refer to
Section 6C for
further information on the fuel tank, line filter, and fuel
pipes.
Fuel Metering System Purpose
The basic function of the air/fuel metering system is to
control the air/fuel delivery to the engine. Fuel is delivered
to the engine by individual fuel injectors mounted in the
intake manifold near each intake valve.
The main control sensor is the heated oxygen sensor
(HO2S) located in the exhaust system. The HO2S tells
the PCM how much oxygen is in the exhaust gas. The
PCM changes the air/fuel ratio to the engine by controlling
the amount of time that fuel injector is ªON.º The best
mixture to minimize exhaust emissions is 14.7 parts of air
to 1 part of gasoline by weight, which allows the catalytic
converter to operate most efficiently. Because of the
constant measuring and adjusting of the air/fuel ratio, the
fuel injection system is called a ªclosed loopº system.