2002 ISUZU AXIOM ECU

6E±341
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P0456 EVAP Very Small Leak
060R200050
Circuit Description
The evaporative system includes the following
components:

Fuel tank

EVAP canister vent solenoid

Fuel tank (vapor) pressure sensor

Vapor lines

Fuel cap

Evaporative emissions canister

Purge lines

EVAP canister purge solenoid
The evaporative leak detection diagnostic strategy is
based on applying vacuum to the EVAP system and
monitoring vacuum decay. The powertrain control
module(PCM)monitors vacuum level via the fuel tank
pressure sensor input. At an appropriate time, the
EVAP canister purge solenoid and the EVAP
canister vent solenoid are turned ªONº, allowing
engine vacuum to draw a very small look on the
entire evaporative emissions system. After the
desired vacuum level has been achieved, the EVAP
canister purge solenoid is turned ªOFFº, sealing the
system. A leak is detected by monitoring for a
decrease in vacuum level over a given time period,
all other variables remaining constant.
A very small leak in the system will cause DTC
P0456 to be set.
Conditions for setting the DTC

No MAP DTC's set.

No TPS DTC's set.

No IAT DTC's set.

No ECT DTC's set.

No tank pressure sensor DTC's set.

Baro is more than 70KPa.

Fuel level is between 40% and 80%.

Throttle angle is less than 3%.

Engine speed is less than 1200 RPM.

Vehicle speed is less than 5 mph (8 km/h).

A vacuum decay condition, indicating a very small leak,
is detected during the diagnostic test.
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 will store condition which were present when
the DTC was set as Freeze Frame and in the Failure
Records data.
Warm up cycles have occurred without a fault.
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.

6E±342
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS

A history DTC P0456 will clear after 40 consecutive trip
cycle during which the warm up cycles have occurred
without a fault.

DTC P0456 can be cleared using the Tech 2 ªClear
Infoº function or by disconnecting the PCM battery
feed.
Diagnostic Aids
Check for the following conditions:

Cracked or punctured EVAP canister.

Damaged source vacuum line, EVAP purge line, EVAP
vent hose or fuel tank vapor line. to wire connection.

Poor connection at PCM±Inspect harness connectors
for backed out terminals, improper mating, broken
locks, improperly formed or damaged terminals, and
poor terminal to wire connection.

Damaged harness-Inspect the wiring harness to the
EVAP canister purge solenoid and the fuel tank
pressure sensor for an intermittent open or short
circuit.
Reviewing the Failure Records vehicle mileage since
the diagnostic test last failed may help determine
how often the condition that caused the DTC to be
set occurs.
This may assist in diagnosing the condition.

6E±344
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P0461 Fuel Level Sensor Performance
060RY00163
Circuit Description
The fuel level sensor is an important input to powertrain
control module (PCM) for the enhanced evaporative
system diagnostic. Fuel level information is needed for
the PCM to know the volume of fuel in the tank. The fuel
level affects the rate of change in air pressure in the
evaporative system.
The sending unit is a float in the fuel tank which moves a
wiper arm across a variable resistor. Low fuel level
causes high resistance in the sending unit, and this is
recognized by the PCM because the circuit operates at a
corresponding low voltage. When the circuit is
continuously open or has a high resistance connection,
DTC P0461 is set.
Conditions for Setting the DTC

Sensor output change is more than 2% within 200km.
Or Sensor movement position change is less than
15% within 200km.

IAT is more than 0
C.

MAP changing in 3 sec is less than 10kPa.

Engine speed changing in 3 sec is less than 50rpm.When there are 12 test failures within 80 test samples, it is
stored.
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 will store conditions which were present
when the DTC was set as Freeze Frame and in the
Failure Records data.
Conditions for Clearing the DTC

DTC P0461 can be cleared by using the scan tool
ªClear Infoº function or by disconnecting the PCM
battery feed.
Diagnostic Aids

Damaged harness±Inspect the wiring harness for
damage. If the harness appears to be OK, observe the
fuel level display on the scan tool while moving
connectors and wiring harnesses related to the sensor.
A change in the display will indicate the location of the
fault.

6E±346
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC)
P0462 Fuel Level Sensor Circuit±Low Voltage
060RY00163
Circuit Description
The fuel level sensor is an important input to powertrain
control module (PCM) for the enhanced evaporative
system diagnostic. Fuel level information is needed for
the PCM to know the volume of fuel in the tank. The fuel
level affects the rate of change in air pressure in the
evaporative system. Several of the enhanced
evaporative system diagnostic sub-tests are dependent
upon correct fuel level information. The diagnostic will not
run when the tank is more than 85% or less than 15% full.
Fuel level DTCs should be diagnosed before other
evaporative system DTCs because they can cause other
DTCs to be set.
The sending unit is a float in the fuel tank which moves a
wiper arm across a variable resistor. Low fuel level
causes high resistance in the sending unit, and this is
recognized by the PCM because the circuit operates at a
corresponding low voltage. When the circuit is
continuously open or has a high resistance connection,
DTC P0462 is set.
Conditions for Setting the DTC

Fuel tank level ªslosh testº is completed.

Fuel tank level ªmain testº is completed.

Fuel tank level data is valid.

Fuel tank level signal is less than a specified value.

There are 100 test failures within a 200-test sample.
Action Taken When the DTC Sets

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

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 DTC

The PCM will turn the MIL ªOFFº after three
consecutive trips without a fault condition present. A
history DTC will be cleared if no fault conditions have
been detected for 40 warm-up cycles (engine coolant
temperature has risen 4
C (40
F) from the start-up
ECT, and ECT exceeds 71
C (160
F) during that
same ignition cycle).

DTC P0462 can be cleared by using the scan tool
ªClear Infoº function or by disconnecting the PCM
battery feed.
Diagnostic Aids

Damaged harness±Inspect the wiring harness for
damage. If the harness appears to be OK, observe the
fuel level display on the scan tool while moving
connectors and wiring harnesses related to the sensor.
A change in the display will indicate the location of the
fault.

6E±349
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC)
P0463 Fuel Level Sensor Circuit±High Voltage
060RY00163
Circuit Description
The fuel level sensor is an important input to powertrain
control module (PCM) for the enhanced evaporative
system diagnostic. Fuel level information is needed for
the PCM to know the volume of fuel in the tank. The fuel
level affects the rate of change in air pressure in the
evaporative system. Several of the enhanced
evaporative system diagnostic sub-tests are dependent
upon correct fuel level information. The diagnostic will not
run when the tank is more than 85% or less than 15%, full.
Fuel level DTCs should be diagnosed before other
evaporative system DTCs because they can cause other
DTCs to be set.
The sending unit is a float in the fuel tank which moves a
wiper arm across a variable resistor. High fuel level
causes low resistance in the sending unit. This is
recognized by the PCM because the circuit operates at a
corresponding high voltage. When the circuit is
continuously shorted to a voltage source greater than a
specified value, or when the 5 volt signal is shorted to
ground, DTC P0463 is set.
Conditions for Setting the DTC

Fuel tank level ªslosh testº is completed.

Fuel tank level ªmain testº is completed.

Fuel tank level data is valid.

Fuel tank level signal is greater than a specified value.

There are 100 test failures within a 200-test sample.
Action Taken When the DTC Sets

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

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 DTC

The PCM will turn the MIL ªOFFº after three
consecutive trips without a fault condition present. A
history DTC will be cleared if no fault conditions have
been detected for 40 warm-up cycles (engine coolant
temperature has risen 4
C (40
F) from the start-up
ECT, and ECT exceeds 71
C (160
F) during that
same ignition cycle) or the scan tool clearing function
has been used.

DTC P0463 can be cleared by using the scan tool
ªClear Infoº function or by disconnecting the PCM
battery feed.

6E±351
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P0462 Fuel Level Sensor Noisy Signal
060RY00163
Circuit Description
The fuel level sensor is an important input to powertrain
control module (PCM) for the enhanced evaporative
system diagnostic. Fuel level information is needed for
the PCM to know the volume of fuel in the tank. The fuel
level affects the rate of change in air pressure in the
evaporative system.
The sending unit is a float in the fuel tank which moves a
wiper arm across a variable resistor. Low fuel level
causes high resistance in the sending unit, and this is
recognized by the PCM because the circuit operates at a
corresponding low voltage. When the circuit is
continuously open or has a high resistance connection,
DTC P0464 is set.
Conditions for Setting the DTC

Sensor output changing is more than 15%.

Fuel volume level is more than 0.01%.

IAT is more than 0
C.

Vehicle speed is more than 1km/h.

Throttle position is more than 2%.When there are 12 test failures within 80 test samples, it is
stored.
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 will store conditions which were present
when the DTC was set as Freeze Frame and in the
Failure Records data.
Conditions for Clearing the DTC

DTC P0464 can be cleared by using the scan tool
ªClear Infoº function or by disconnecting the PCM
battery feed.
Diagnostic Aids

Damaged harness±Inspect the wiring harness for
damage. If the harness appears to be OK, observe the
fuel level display on the scan tool while moving
connectors and wiring harnesses related to the sensor.
A change in the display will indicate the location of the
fault.

6E±353
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P0502 VSS Circuit Low Input
060R200056
Circuit Description
The vehicle speed sensor has a magnet rotated by the
transmission output shaft. Attached to the sensor is a hall
effect circuit the interacts with the magnetic field treated
by the rotating magnet. A 12-volt operating supply for the
speed sensor hall circuit is supplied from the meter fuse.
The VSS pulses to ground the 9-volt signal sent from the
powertrain control module (PCM) on the reference circuit.
The PCM interprets vehicle speed by the number of
pulses to ground per second on the reference circuit.
Conditions for Setting the DTC

Engine is running.

Engine speed is between 1800 RPM and 2500 RPM.

Throttle angle is between 10% and 40%.

Engine load is greater than 50 kPa.

PCM detects no VSS signal for 12.5 seconds over a
period of 15 seconds.
Action Taken When the DTC Sets

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

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 P0502 will clear after 40 consecutive
warm-up cycles have occurred without a fault.

DTC P0502 can be cleared by using the Tech 2 ªClear
Infoº function or by disconnecting the PCM battery
feed.
Test Description
Number(s) below refer to the step number(s) on the
Diagnostic Chart.
10. To avoid backprobing the VSS and possibly
damaging a seal or terminal, the VSS output can be
tested at the point where the transmission harness
connects to the engine harness. Power and ground
are applied by jumpers to the VSS through the
connectors which are located to the rear of the air
cleaner assembly. The VSS signal is monitored
with a DVM as the rear driveshaft turns. The
wheels can be turned to rotate the driveshaft, or in
2-wheels-drive vehicles the driveshaft can be turned
directly.

6E±356
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P0506 Idle Air Control System Low RPM
060R200057
Circuit Description
The powertrain control module (PCM) controls engine
speed by adjusting the position of the throttle control
valve (DC motor). The throttle motor is a DC motor driven
by one coil. The PCM applies current to the DC motor coil
in position (%) to adjustment the throttle valve into a
passage in the throttle body to air flow. This method
allows highly accurate control of engine speed and quick
response to changes in engine load.
If the PCM detects a condition where too low of an idle
speed is present and the PCM is unable to adjust idle
speed by increasing the throttle position, DTC P0506 will
set, indicating a problem with the idle control system.
Conditions for Setting the DTC

No TPS, VSS, ECT, EGR, MAF, MAP, IAT, low voltage,
fuel system, canister purge, injector control, or ignition
control DTCs are set.

MAP is less than 60 kPa.

Canister purge duty cycle is above 10%.

Engine running time is more than 125 seconds.

Vehicle speed is less than 1 mph.

Engine coolant temperature (ECT) is above 50
C
(122
F).

Ignition voltage is between 9.5 volts and 16.7 volts.

The throttle is closed.

EVAP purge duty cycle more than 10%.

All conditions are met for 10 seconds.

Barometric pressure is more than 74.5 kPa.
Engine speed is more than 100-200 RPM lower than
desired idle based upon coolant temperature.
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 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 P0506 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:

Poor connection at PCM or throttle DC motor ± Inspect
harness connectors for backed-out terminals,
improper mating, broken locks, improperly formed or
damaged terminals, and poor terminal-to-wire
connection.

Damaged harness ± Inspect the wiring harness for
damage.

Restricted air intake system ± Check for a possible
collapsed air intake duct, restricted air filter element, or
foreign objects blocking the air intake system.

Throttle body ± Check for objects blocking the ETC
passage or throttle bore, excessive deposits in the