2002 ISUZU AXIOM open gas tank

1A±20
HEATING, VENTILATION AND AIR CONDITIONING (HVAC)
A condenser may malfunction in two ways: it may leak, or
it may be restricted. A condenser restriction will result in
excessive compressor discharge pressure. If a partial
restriction is present, the refrigerant expands after
passing through the restriction.
Thus, ice or frost may form immediately after the
restriction. If air flow through the condenser or radiator is
blocked, high discharge pressures will result. During
normal condenser operation, the refrigerant outlet line will
be slightly cooler than the inlet line.
The vehicle is equipped with the parallel flow type
condenser. A larger thermal transmission area on the
inner surface of the tube allows the radiant heat to
increase and the ventilation resistance to decrease.
The refrigerant line connection has a bolt at the block
joint, for easy servicing.
875R200015
Legend
(1) Pressure Switch
(2) Receiver Drier
(3) Condenser & Receiver Tank Assembly
(4) Condenser Fan
Receiver / Drier
The receiver/drier performs four functions:

As the quantity of refrigerant circulated varies
depending on the refrigeration cycle conditions,
sufficient refrigerant is stored for the refrigeration
cycle to operate smoothly in accordance with
fluctuations in the quantity circulated.

The liquefied refrigerant from the condenser is mixed
with refrigerant gas containing air bubbles. If
refrigerant containing air bubbles. If refrigerant
containing air bubbles is sent to the expansion valve,
the cooling capacity will decrease considerably.
Therefore, the liquid and air bubbles are separated
and only the liquid is sent to the expansion valve.

The receiver/drier utilizes a filter and drier to remove
the dirt and water mixed in the cycling refrigerant.A receiver/drier may fail due to a restriction inside the
body of the unit. A restriction at the inlet to the
receiver/drier will cause high pressure.
Outlet restrictions will be indicated by low pressure and
little or no cooling. An excessively cold receiver/drier
outlet may indicate a restriction.
The receiver/drier of this vehicle is made of aluminum
with a smaller tank. It has a 300cc refrigerant capacity.
The refrigerant line connection has a bolt at the block
joint, for easy servicing.
Triple Pressure Switch (V6, A/T)
Triple pressure switch is installed on the upper part of the
receiver/drier. This switch is constructed with a unitized
type of two switches. One of them is a low and high
pressure switch (Dual pressure switch) to switch ªONº or
ªOFFº the magnetic clutch as a result of irregularly
high±pressure or low pressure of the refrigerant. The
other one is a medium pressure switch (Cycling switch) to
switch ªONº or ªOFFº the condenser fan sensing the
condenser high side pressure.
Compressor
ON
(kPa/psi)OFF
(kPa/psi)
Low-pressure
control206.0+30.0
(29.8+4.3)176.5+24.5
(25.6+3.6)
High-pressure
control2353.6+196.1
(341.3+28.4)2942.0+196.1
(426.6+28.4)
Condenser fanON
(kPa/psi)OFF
(kPa/psi)
Medium-pressure
control1471.0+98.1
(213.3+14.2)1078.7+117.7
(156.4+17.1)
Expansion Valve
This expansion valve is an external pressure type and it is
installed at the evaporator intake port.
The expansion valve converts the high pressure liquid
refrigerant sent from the receiver/drier to a low pressure
liquid refrigerant by forcing it through a tiny port before
sending it to the evaporator.
This type of expansion valve consists of a temperature
sensor, diaphragm, ball valve, ball seat, spring
adjustment screw, etc.
The temperature sensor contacts the evaporator outlet
pipe, and converts changes in temperature to pressure. It
then transmits these to the top chamber of the
diaphragm.
The refrigerant pressure is transmitted to the diaphragm's
bottom chamber through the external equalizing pressure
tube.
The ball valve is connected to the diaphragm. The
opening angle of the expansion valve is determined by
the force acting on the diaphragm and the spring
pressure.

6A±14
ENGINE MECHANICAL (6VE1 3.5L)
Abnormal Combustion
ConditionPossible causeCorrection
Trouble in fuel systemFuel pressure control valve defectiveReplace
Fuel filter cloggedReplace
Fuel pump cloggedClean or replace
Fuel tank or fuel pipe cloggedClean or replace
Fuel injector cloggedClean or replace
Fuel pump relay defectiveReplace
Power supply cable for fuel pump
broken or poor connectionsReconnect, correct or replace
Mass Airflow (MAF) Sensor circuit
open or defectiveCorrect or replace
MAF Sensor defectiveReplace
Manifold Absolute Pressure Sensor
circuit open or shortedCorrect or replace
Manifold Absolute Pressure Sensor
defectiveReplace
Engine Coolant Temperature (ECT)
Sensor circuit open or shortedCorrect or replace
ECT Sensor defectiveReplace
Throttle Position Sensor adjustment
incorrectReadjust
Throttle Position Sensor defectiveReplace
Throttle Position Sensor connector
poor connectionsReconnect
Vehicle Speed Sensor cable poor
connections or defectiveCorrect or replace
Vehicle Speed Sensor loosely fixedFix tightly
Vehicle Speed Sensor in wrong
contact or defectiveReplace
Powertrain Control Module cable
poor connections or defectiveCorrect or replace
Trouble in emission control systemHeated Oxygen Sensor circuit openCorrect or replace
Heated Oxygen Sensor defectiveReplace
Signal vacuum hose loosely fitted or
defectiveCorrect or replace
EGR Valve circuit open or shortedCorrect or replace
Exhaust Gas Recirculation Valve
defectiveReplace
ECT Sensor circuit open or shortedCorrect or replace
Canister Purge Valve circuit open or
shortedCorrect or replace
Canister Purge Valve defectiveReplace
ECT Sensor defectiveReplace
Positive Crankcase Ventilation
(PCV) valve and hose cloggedCorrect or replace
Evaporator systemRefer to Section 6E
Trouble in ignition systemÐÐÐÐRefer to ªEngine Lacks Powerº

6E±143
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P0107 MAP Sensor Circuit Low Voltage
060R200051
Circuit Description
The manifold absolute pressure (MAP) sensor responds
to changes in intake manifold pressure (vacuum). The
MAP sensor signal voltage to the powertrain control
module (PCM) varies from below 2 volts at idle (high
vacuum) to above 4 volts with the ignition ªONº, engine
not running or at wide-open throttle (low vacuum).
The MAP sensor is used to determine manifold pressure
changes while the exhaust gas recirculation (EGR) flow
test diagnostic is being run (refer to
DTC P0401), to
determine engine vacuum level for some other
diagnostics and to determine barometric pressure
(BARO). The PCM monitors the MAP signals for voltages
outside the normal range of the MAP sensor. If the PCM
detects a MAP signal voltage that is excessively low, DTC
P0107 will be set.
Conditions for Setting the DTC

No TP sensor DTCs present.

Engine is running.

Throttle angle is above 1% if engine speed is less than
1000 RPM.

Throttle angle is above 2% if engine speed is above
1000 RPM.

The MAP sensor indicates manifold absolute pressure
at or below 11 kPa for a total of approximately 10
seconds over a 16-second period.

Ignition voltage more than 11 volts.
Action Taken When the DTC Sets

The PCM will ON the MIL after second trip with
detected fault.

The PCM will default to a BARO value of 79.3 kPa.

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

The PCM will turn the MIL ªOFFº on the third
consecutive trip cycle during which the diagnostic has
been run and the fault condition is no longer present.

A history DTC P0107 will clear after 40 consecutive
warm-up cycles have occurred without a fault.

DTC P0107 can be cleared by using the Tech 2 ªClear
Infoº function or by disconnecting the PCM battery
feed.
Diagnostic Aids
Check for the following conditions:

Check for intermittent codes.

The MAP sensor shares a 5 Volt reference with the
Fuel Tank Pressure Sensor. If these codes are also
set, it could indicate a problem with the 5 Volt reference
circuit .

The MAP sensor shares a ground with the Fuel Tank
Pressure Sensor, the ECT sensor, and the
Transmission Fluid Temperature sensor.

Poor connection at PCM ± Inspect harness connectors
for backed-out terminals, improper mating, broken

6E±514
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Detonation/Sparks Knock Symptoms

StepActionValue(s)Ye sNo
1DEFINITION:
A mild to severe ping, usually worse under acceleration.
The engine makes sharp metallic knocks that change
with throttle opening.
Was the ªOn-Board Diagnostic (OBD) System Checkº
performed?
ÐGo to Step 2
Go to OBD
System
Check
21. Perform a bulletin search.
2. If a bulletin that addresses the symptom is found,
correct the condition as instructed in the bulletin.
Was a bulletin found that addresses the symptom?
ÐVerify repairGo to Step 3
3Was a visual/physical check performed?
ÐGo to Step 4
Go to Visual/
Physical
Check
4If Tech 2 readings are normal (refer to Typical Scan
Values
) and there are no engine mechanical faults, fill
the fuel tank with a known quality gasoline that has a
minimum octane rating of 87 and re-evaluate the
vehicle performance.
Is detonation present?
ÐGo to Step 5Verify repair
51. Check the transmission range switch circuit. Use a
Tech 2 and be sure the Tech 2 indicates that the
vehicle is in drive with the gear selector in drive or
overdrive.
2. If a problem is found, diagnose and repair the
transmission range switch as necessary (refer to
4L30-E Automatic Transmission Diagnosis).
Was a problem found?
ÐVerify repairGo to Step 6
61. Check TCC operation. Refer to 4L30-E
Transmission Diagnosis
.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 7
71. Check for obvious overheating problems:

Low engine coolant.

Restricted air flow to radiator, or restricted
water flow through radiator.

Correct coolant solution should be a 50/50 mix
of approved antifreeze/coolant and water.
Refer to
Engine Cooling.

EGR operation. Refer to
DTC P0401.

ION sensing module fault.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 8
81. Ignition ªOFFº.
2. Disconnect the ION sensing module.
3. Disconnect the PCM.
Is the action complete?
ÐGo to Step 9Ð
9Check the ION sensing harness between the PCM
(F68) and ION sensing module circuit (RED Wire) at
the Kl line harness connector.
Was a problem found?
ÐVerify repairGo to Step 10

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.

6E±583
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
between the seats. In extreme cases, exhaust blow-by
and damage beyond simple gap wear may occur.
Cracked or broken insulators may be the result of
improper installation, damage during spark plug
re-gapping, or heat shock to the insulator material. Upper
insulators can be broken when a poorly fitting tool is used
during installation or removal, when the spark plug is hit
from the outside, or is dropped on a hard surface. Cracks
in the upper insulator may be inside the shell and not
visible. Also, the breakage may not cause problems until
oil or moisture penetrates the crack later.
TS23994
A/C Clutch Diagnosis
A/C Clutch Circuit Operation
A 12-volt signal is supplied to the A/C request input of the
PCM when the A/C is selected through the A/C control
switch.
The A/C compressor clutch relay is controlled through the
PCM. This allows the PCM to modify the idle air control
position prior to the A/C clutch engagement for better idle
quality. If the engine operating conditions are within their
specified calibrated acceptable ranges, the PCM will
enable the A/C compressor relay. This is done by
providing a ground path for the A/C relay coil within the
PCM. When the A/C compressor relay is enabled,
battery voltage is supplied to the compressor clutch coil.
The PCM will enable the A/C compressor clutch
whenever the engine is running and the A/C has been
requested. The PCM will not enable the A/C compressor
clutch if any of the following conditions are met:

The throttle is greater than 90%.

The engine speed is greater than 6315 RPM.

The ECT is greater than 119
C (246
F).

The IAT is less than 5
C (41
F).

The throttle is more than 80% open.
A/C Clutch Circuit Purpose
The A/C compressor operation is controlled by the
powertrain control module (PCM) for the following
reasons:

It improvises idle quality during compressor clutch
engagement.

It improvises wide open throttle (WOT) performance.

It provides A/C compressor protection from operation
with incorrect refrigerant pressures.
The A/C electrical system consists of the following
components:

The A/C control head.

The A/C refrigerant pressure switches.

The A/C compressor clutch.

The A/C compressor clutch relay.

The PCM.
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 on 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 A/C electrical system.
General Description (Evaporative
(EVAP) Emission System)
EVAP Emission Control System Purpose
The basic evaporative emission (EVAP) control system
used on all vehicles is the charcoal canister storage
method. Gasoline vapors from the fuel tank flow into the
canister through the inlet labeled ªTANK.º These vapors
are absorbed into the activated carbon (charcoal) storage
device (canister) in order to hold the vapors when the
vehicle is not operating. The canister is purged by PCM
control when the engine coolant temperature is over 60
C
(140
F), the IAT reading is over 10
C (50
F), and the
engine has been running. Air is drawn into the canister
through the air inlet grid. The air mixes with the vapor and
the mixture is drawn into the intake manifold.
EVAP Emission Control System Operation
The EVAP canister purge is controlled by a solenoid valve
that allows the manifold vacuum to purge the canister.
The powertrain control module (PCM) supplies a ground
to energize the solenoid valve (purge on). The EVAP
purge solenoid control is pulse-width modulated (PWM)
(turned on and off several times a second). The duty
cycle (pulse width) is determined by engine operating
conditions including load, throttle positron, coolant
temperature and ambient temperature. The duty cycle is
calculated by the PCM. The output is commanded when
the appropriate conditions have been met. These
conditions are:

The engine is fully warmed up.

The engine has been running for a specified time.

The IAT reading is above 10
C (50
F).

6E±584
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
A continuous purge condition with no purge commanded
by the PCM will set a DTC P1441.
Poor idle, stalling and poor driveability can be caused by:

A malfunctioning purge solenoid.

A damaged canister.

Hoses that are split, cracked, or not connected
properly.
Enhanced Evaporative Emission Control
System
The basic purpose of the Enhanced Evaporative
Emissions control system is the same as other EVAP
systems. A charcoal-filled canister captures and stores
gasoline fumes. When the PCM determines that the time
is right, it opens a purge valve which allows engine
vacuum to draw the fumes into the intake manifold.
The difference between this and other systems is that the
PCM monitors the vacuum and/or pressure in the system
to determine if there is any leakage. If the PCM
determines that the EVAP system is leaking or not
functioning properly, it sets a Diagnostic Trouble Code
(DTC) in the PCM memory.
The enhanced EVAP system is required to detect
evaporative fuel system leaks as small as 0.020 in. (1.0
mm) between the fuel filler cap and purge solenoid. The
system can test the evaporative system integrity by
applying a vacuum signal (ported or manifold) to the fuel
tank to create a small vacuum. The PCM then monitors
the ability of the system to maintain the vacuum. If the
vacuum remains for a specified period of time, there are
no evaporative leaks and a PASS report is sent to the
diagnostic executive. If there is a leak, the system either
will not achieve a vacuum, or a vacuum cannot be
maintained. Usually, a failure can only be detected after a
cold start with a trip of sufficient length and driving
conditions to run the needed tests. The enhanced EVAP
system diagnostic will conduct up to eight specific
sub-tests to detect fault conditions. If the diagnostic fails
a sub-test, the PCM will store a Diagnostic Trouble Code
(DTC) to indicate the type of detected.

6E±586
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Electrical Components
The electrical components that make up the enhanced
EVAP system are:

Fuel Tank (Vapor) Pressure Sensor. The fuel tank
pressure sensor is a three-wire strain gauge sensor
similar to a common MAP sensor. However, the fuel
tank pressure sensor has very different electrical
characteristics due to its pressure differential design.
The sensor measures the difference between the air
pressure (or vacuum) in the fuel tank and the outside
air pressure.
The sensor mounts at the top of the fuel pump
assembly. A three-wire electrical harness connects it to
the PCM. The PCM supplies a five-volt reference
voltage and a ground to the sensor. The sensor will
return a voltage between 0.1 and 4.9 volts. When the
air pressure in the fuel tank is equal to the outside air
pressure, such as when the fuel cap is removed, the
output voltage of the sensor will be 1.3 to 1.7 volts.
When the air pressure in the fuel tank is 4.5 in. H2O
(1.25 kPa), the sensor output voltage will be 0.5 + 0.2 V.
When there is neither vacuum nor pressure in the fuel
tank, the sensor voltage will be 1.5 V. At ±14 in. H2O
(±3.75 kPa), the sensor voltage will be 4.5 + 0.2 V.

EVAP Canister Purge Solenoid. Normally closed, the
purge solenoid opens upon the PCM's signal to allow
engine vacuum to purge gasoline fumes from the
canister. Mounted on the water pipe to front of the
engine assembly.
060R200080

EVAP Canister Vent Solenoid. Located next to the
canister, the vent solenoid opens to allow air into the
EVAP system. Fresh air is necessary to completely
remove gasoline fumes from the canister during
purge. The EVAP vent solenoid closes to seal off the
evaporative emissions system for leak testing.
060R200081

Fuel Level Sensor. The fuel level sensor is an
important input to the PCM for the enhanced EVAP
system diagnostic. The PCM needs fuel level
information to know the volume of fuel in the tank.
The fuel level affects the rate of change of air
pressure in the EVAP system. Several of the
enhanced EVAP system diagnostic sub-tests are
dependent upon correct fuel level information. The
diagnostic will not run when the tank is less than 15%
or more than 85% full. Be sure to diagnose any Fuel
Level Sensor DTCs first, as they can cause other
DTCs to set.
014RW114

Manifold Absolute Pressure (MAP) Sensor. The
PCM compares the signals from the fuel tank
pressure sensor and the MAP sensor to ensure that a
relative vacuum is maintained the EVAP system.