2002 ISUZU AXIOM ECU

6E±414
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
DTC P1153 ± HO2S Insufficient Switching Bank 2 Sensor 1

 
StepNo Ye s Value(s) Action
11Replace the exhaust pipes, as required.
Is your action complete?
ÐGo to Step 2Ð
12Check for leaks at the exhaust manifold.
Are there leaks at the exhaust manifold?
ÐGo to Step 13Go to Step 14
13Tighten the bolts to specifications or replace the
manifold if necessary.
Is your action complete?
ÐGo to Step 2Ð
14Visually/physically inspect the following items:

Ensure that the Bank 2 HO2S 1 is securely
installed.

Check for corrosion on terminals.

Check the terminal tension at Bank 2 HO2S 1 and
at the PCM.

Check for damaged wiring.
Was a problem found in any of the above areas?
ÐVerify repairGo to Step 15
151. Disconnect Bank 2 HO2S 1.
2. Ignition ªONº.
3. Using a DVM at the PCM side of the connector,
check the voltage between the high signal circuit
and ground. Also measure between the low signal
circuit and ground.
Are both voltages in the specified range?
3-4VGo to Step 18Go to Step 16
161. Ignition ªONº.
2. Check for damage to PCM pins or terminals.
Was a problem found?
ÐVerify repairGo to Step 17
17Check for short to voltage or ground or an open in the
signal circuit.
Was a problem found?
ÐVerify repairGo to Step 18
181. Ignition ªOFFº.
2. Disconnect the PCM connector.
3. With HO2S disconnected, check for high and low
signal circuits shorted together between the PCM
and HO2S.
Was a problem found?
ÐVerify repairGo to Step 19
19With the PCM connected and Bank 2 HO2S 1
disconnected from the harness, check Bank 2 HO2S 1
with a Tech 2.
Is the voltage in the specified range?
425-475 mVGo to Step 21Go to Step 22
20Replace affected heated oxygen sensors.
NOTE: Before replacing sensors, the cause of the
contamination must be determined and corrected.

Fuel contamination.

Use of improper RTV sealant.

Engine oil/coolant consumption.
Is the action complete?
ÐVerify repairÐ

6E±416
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC)
P1154 HO2S Circuit Transition Time Ratio Bank 2 Sensor 1
060R200054
Circuit Description
The powertrain control module (PCM) monitors the
heated oxygen sensor (HO2S) activity for 90 seconds
after ªclosed loopº and stoichiometric operation have
been enabled. During the monitor period the PCM counts
the number of times that the HO2S responds from
rich-to-lean and from lean-to-rich and adds the amount of
time it took to complete all transitions. With this
information, an average time for all transitions can be
determined. The PCM then divides the rich-to-lean
average by the lean-to-rich average to obtain a ratio. If
the HO2S transition time ratio is not within this range,
DTC P1154 will be set, indicating that the oxygen sensor
is not responding as expected to changes in exhaust
oxygen content.
Conditions for Setting the DTC

No related DTCs.

Engine coolant temperature (ETC) is above 60
C
(140
F).

The engine is operating in ªclosed loopº,

The engine has been running at least one minute.

Canister purge duty cycle is greater than 2%.

Engine speed is between 1500 RPM and 3000 RPM.

Mass air flow is between 18 g/second and 42 g/second.

Above conditions are present for a 3-second
monitoring period.
90 seconds after ªclosed loopº and stoichiometric
operation have been enabled, Bank 2 HO2S 1
transition ratio between lean to rich and rich to lean is
less than 0.44 or greater than 3.8.
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.

ºOpen loopº fuel control will be in effect.

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 P1154 will clear after 40 consecutive
warm-up cycles have occurred without a fault.

DTC P1154 can be cleared by using the Tech 2 ªClear
Infoº function or by disconnecting the PCM battery
feed.
Diagnostic Aids
A multifunction in the HO2S heater ignition feed or ground
circuit may cause a DTC P1154 to set. Check HO2S
heater circuitry for intermittent faults or poor connections.

6E±418
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
DTC P1154 ± HO2S Transition Time Ratio Bank 2 Sensor 1

 
StepNo Ye s Value(s) Action
12Check for leaks at the exhaust manifold.
Are there leaks at the exhaust manifold?
ÐGo to Step 13Go to Step 14
13Tighten the bolts to specifications or replace the
manifold if necessary.
Is your action complete?
ÐGo to Step 2Ð
14Visually/physically inspect the following items:

Ensure that the Bank 2 HO2S 1 is securely
installed.

Check for corrosion on terminals.

Check terminal tension (at Bank 2 HO2S 1 and at
the PCM).

Check for damaged wiring.
Was a problem found in any of the above areas?
ÐGo to Step 18Go to Step 15
151. Disconnect Bank 2 HO2S 1.
2. Ignition ªONº.
3. Using a DVM at the PCM side of the HO2S 1
connector, measure the voltage between the high
signal circuit and ground.
Also measure the voltage between the low signal
circuit and ground.
Are both voltages in the specified range?
3-4 VGo to Step 16Go to Step 19
161. With Bank 2 HO2S 1 disconnected, jumper the high
and low (PCM side) signal circuits to ground.
2. Ignition ªONº.
3. Using a Tech 2, monitor the Bank 2 HO2S 1 voltage.
Does the Tech 2 indicate less than 10 mV and
immediately return to about 450 mV when the jumper is
removed?
ÐGo to Step 21Go to Step 22
17Replace affected heated oxygen sensors.
NOTE: Before replacing sensors, the cause of the
contamination must be determined and corrected.

Fuel contamination.

Use of improper RTV sealant.

Engine oil/coolant consumption.
Is the action complete?
ÐVerify repairÐ
18Repair condition as necessary.
Is the action complete?
ÐVerify repairÐ
19Check for faulty PCM connections or terminal damage.
Is the action complete?
ÐVerify repairGo to Step 20
20Repair open, short or grounded signal circuit.
Is the action complete?
ÐVerify repairÐ

6E±420
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC)
P1167 Fuel System Rich During Decel Fuel Cut Off (Bank 1)
060R200054
Circuit Description
The powertrain control module (PCM) continuously
monitors the heated oxygen sensor (HO2S) activity for 90
seconds after ªclosed loopº has been enabled. During the
monitoring period the powertrain control module (PCM)
counts the number of times a rich to lean response is
indicated and adds the amount of time it look to complete
all rich to lean transitions and lean to rich transitions.
This code detects if Bank1 O2 sensor indicated rich
exhaust while in Decel Fuel Cut Off (DFCO) for fuel
control sensors.
Conditions for setting the DTC

No related DTCs.

The engine coolant temperature is more than 60
C
(140
F).

Engine is operating in ªclosed loopº power enrichment
mode for 3 seconds.

While in ªpower enrichmentº mode the oxygen sensor
voltage remains more than 600mV in DFCO.
Action Taken When the DTC Sets

The PCM will not illuminate the malfunction
malfunction indicator lamp (MIL).

The PCM will store conditions which were present
when the DTC was set as Failure Records only. This
information will not be stored as Freeze Frame data.
Conditions for Clearing the MIL/DTC

A history DTC P1167 will clear after 40 consecutive trip
cycles during which the warm up cycles have occurred
without a fault.

DTC P1167 can be cleared using the Tech 2 ªClear
Infoº function or by disconnecting the PCM battery
feed.
Diagnostic Aids

Check for faulty fuel injectors and fuel pump.

6E±422
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC)
P1169 Fuel System Rich During Decel Fuel Cut Off (Bank 2)
060R200054
Circuit Description
The powertrain control module(PCM)
continuously monitors the heated oxygen sensor (HO2S)
activity for 90 seconds after ªclosed loopº has been
enabled. During the monitoring period the powertrain
control module (PCM) counts the number of times a rich
to lean response is indicated and adds the amount of time
it look to complete all rich to lean transitions and lean to
rich transitions.
This code detects if Bank2 sensor indicated rich exhaust
while in Decel Fuel Cut Off (DFCO) for fuel control
sensors.
Conditions for setting the DTC

No related DTCs.

The engine coolant temperature is more than 60
C
(140
F).

Engine is operating in ªclosed loopº power enrichment
mode for 3 seconds.

While in ªpower enrichmentº mode the oxygen sensor
voltage remains more than 600mV in DFCO.
Action Taken When the DTC Sets

The PCM will not illuminate the malfunction
malfunction indicator lamp(MIL).

The PCM will store conditions which were present
when the DTC was set as Failure Records only. This
information will not be stored as Freeze Frame data.
Conditions for Clearing the MIL/DTC

A history DTC P1169 will clear after 40 consecutive trip
cycles during which the warm up cycles have occurred
without a fault.

DTC P1169 can be cleared using the Tech 2 ªClear
Infoº function or by disconnecting the PCM battery
feed.
Diagnostic Aids

Check for faulty fuel injectors and fuel pump.

Check the pressure regulator.

6E±424
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC)
P1171 Fuel System Lean During Acceleration
060R200054
Circuit Description
The powertrain control module (PCM) internal circuitry
can identify if the vehicle fuel system is capable of
supplying adequate amounts of fuel during heavy
acceleration (power enrichment). The PCM monitors the
voltage of the oxygen sensor during power enrichment.
When a power enrichment mode of operation is
requested during ªclosed loopº operation (by heavy
acceleration), the PCM will provide more fuel to the
engine. Under these conditions the PCM should detect a
ªrichº condition (high oxygen sensor voltage). If this ªrichº
exhaust is not detected at this time, a DTC P1171 will set.
A plugged fuel filter, restricted fuel line, restricted in-tank
filter or defective fuel pump can prevent adequate
amounts of fuel from being supplied during power
enrichment mode.
Conditions for Setting the DTC

No related DTCs.

Engine is operating in ªclosed loop power enrichmentº
mode for 3 seconds.

Engine coolant temperature is above 60
C (140
F).

While in ªpower enrichmentº mode the oxygen sensor
voltage remains below 400 mV for 3 seconds.
Action Taken When the DTC Sets

The PCM will not turn the malfunction indicator lamp
(MIL) ªONº.

The PCM will store conditions which were present
when the DTC was set as Failure Records only. This
information will not be stored as Freeze Frame 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 P1171 will clear after 40 consecutive
warm-up cycles have occurred without a fault.

DTC P1171 can be cleared by using the Tech 2 ªClear
Infoº function or by disconnecting the PCM battery
feed.
Diagnostic Aids

A restricted fuel filter or fuel line, restricted in-tank filter,
or a defective fuel pump may supply adequate
amounts of fuel at idle, but may not be able to supply
enough fuel during heavy acceleration.

Water or alcohol in the fuel may cause low HO2S
voltage during acceleration.

Check for faulty or plugged fuel injector(s).

Check for low fuel.

6E±427
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC)
P1220 Throttle Position Senser2 (TPS2) Circuit Fault
D06RY00111
Circuit Description

The throttle position (TP2) sensor circuit provides a
voltage signal relative to throttle blade angle.
The TPS2 voltage will vary from about 8% (0.4V) to
about 92% (4.6V) at Wide Open Throttle (WOT) in
the specified voltage (about 5V).
This code detects a continuous short to ground or
high in either the circuit or the sensor.
Conditions for setting the DTC

The Ignition is ªONº.

The TPS2 output is more than 93.6 milliseconds, less
than 2.5% or more than 97.5% in the specified voltage
(5V).
Action Taken When the DTC Sets

The PCM will ON the MIL after second trip with
detected 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 P1120 will clear after 40 consecutive trip
cycles during which the warm up cycles have occurred
without a fault.

DTC P1120 can be cleared using the Tech2 ªClear Infoº
function or by disconnecting the PCM battery feed.
Diagnostic Aids
An intermittent may be caused by the following:

Poor connections.

Misrouted harness.

Rubbed through wire insulation.

Broken wire inside the insulation.
Check for the following conditions:

The MAP sensor shares a 5 Volt reference with the
Fuel Tank Pressure. 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, the ECT sensor, and the Transmission Fluid

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 for
damage. If the harness appears to be OK, observe the
TP sensor display on the Tech 2 while moving
connectors and wiring harnesses related to the sensor.
A change in the display will indicate the location of
the fault. If DTC P1120 cannot be duplicated, the

6E±430
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Diagnosis Trouble Code(DTC)
P1221 TPS1 ± TPS2 Correlation(Circuit Performance)
060R200069
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 DC
motor coil in duty (%) to adjustment the 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.

The accelerator position (AP) sensor circuit provides a
voltage signal relative to accelerator pedal angle.
The accelerator pedal angle (AP1) will vary from
about 13% at idle position to about 87% at open
throttle(WOT).
APS signal is used to determine which DC will adjust
throttle position.
After the APS signal has been processed by the
PCM, it will command the DC motor to move the
throttle position.

Accelerator pedal ± Check for objects blocking the AP
sensor or pedal arm with spring, and excessive
deposits in the accelerator pedal arm and on the
accelerator pedal.
Conditions for Setting the DTC

The ignition is ªONº.
A difference of between TPS1 and TPS2 correlation of
over 6.5% within 125 milliseconds.
Action Taken When the DTC Sets

The PCM will not turn the malfunction indicator lamp
(MIL) ªONº.

The PCM will store conditions which were present
when the DTC was set as Failure Records only. This
information will not be stored as Freeze Frame data.
Condition for Clearing the MIL/DTC

A history DTC 1221 will clear after 40 consecutive trip
cycles during which the warm up cycles have occurred
without a fault.

DTC 1221 can be cleared 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:
2. Visually/physically inspect for the following throttle
valve conditions.
3.Visually/physically inspect for the following
accelerator pedal conditions.
5.Check the following circuits for throttle valve and DC
moter. Check the following TP sensor resistance
and DC motor.