engine ISUZU AXIOM 2002 Service Repair Manual

6E±423
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC)
P1169 Fuel System Rich During Decel Fuel Cut Off (Bank2)

StepActionValue(s)Ye sNo
1Was the ªOn-Board (OBD) System Checkº performed?
ÐGo to Step 2
Go to OBD
System
Check
2Are any component related DTCs set?Go to
component
DTC charts
Go to Step 3
31. Place the transmission in Park.
2. Using a Tech 2, HO2S 2 voltage while running warm
engine75 C ± 95 C (167 F ± 203 F) at 1200 RPM.
3. HO2S 1 voltages should vary within the specified
range. (100 ± 900mV)
4. Quickly open the wide open the throttle for a few
seconds.
Did the voltage suddenly rise toward the low end of the
specified range?
100 ± 600 mV
Go to OBD
System
Check
Go to Step 4
41. Disconnect the fuel pump relay and crank the
engine to relieve the fuel pressure.
2. Install the fuel pressure gauge.
3. Start the engine and idle at normal operating
temperature.
4. Disconnect the vacuum line going to the fuel
pressure regulator.
With the engine running, is the fuel pressure within the
specified range?
280 ± 325Kpa
(41 ± 46psi)
Go to OBD
System
Check
Go to Step 5
51. Ignition ªOFFº.
2. Remove the fuel pump relay and replace it with a
fused jumper which will connect the relay's battery
terminal to the terminal leading to the fuel pump
fuse.
3. While the fuel pump is operating, use pliers to slowly
close the return line (do not exceed the first
specified value).
Using the pliers to restrict the return line, can the fuel
pressure be manipulated to exceed the second value?
Is the fuel pressure gauge reading near the specified
value?
325KPa
(46psi)
414KPa
(60psi)
Refer to
Diagnostic
Aids
Go to Step 6
6Check the following items;

Faulty fuel pump

Incorrect fuel pump

Incorrect fuel being used

Cold fuel.
If a problem is found, repair one as necessary.
Was a problem found?
ÐVerify repairÐ

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±425
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Test Description
Number(s) below refer to the step number(s) on the
Diagnostic Chart.
4. When the engine is idling or at steady cruise, the
HO2S voltage should vary from between
approximately 100 mV to 900 mV. It is possible to
measure a satisfactory fuel pressure at idle even
though the pressure may drop at high flow
requirements. It may be necessary to watch fuel
pressure at high engine load.
5. Wrap a shop towel around the fuel pressure
connector to absorb any small amount of fuel
leakage that may occur when installing gauge.
Ignition ªONº, pump pressure should be 280-320
kPa.
7. Add Caution, Use correct pliers so damage to fuel
lines will not occur.

6E±426
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
DTC P1171 ± Fuel System Lean During Acceleration

StepActionValue(s)Ye sNo
1Was the ªOn-Board Diagnostic (OBD) System Checkº
performed?
ÐGo to Step 2
Go to OBD
System
Check
2Are any component-related DTCs set?
Ð
Go to
component
DTC charts
Go to Step 3
31. Check the vehicle's fuel tank for an adequate
amount of fuel.
2. Add fuel to the vehicle's fuel tank if the tank is almost
empty.
Was fuel added to the vehicle's fuel tank?
ÐGo to Step 4Go to Step 5
41. Place the transmission in park.
2. Using a Tech 2, observe HO2S 1 voltage while
running warm engine 75
C-95
C (167
F-203
F) at
1200 RPM.
3. HO2S 1 voltage should vary within the specified
range.
4. Quickly open the throttle too halfway for a few
seconds.
Did the voltage suddenly rise toward the high end of the
specified range?
100-900 mV
Go to Fuel
System
Electrical Test
Go to Step 5
51. Disconnect the fuel pump relay and crank the
engine to relieve the fuel pressure.
2. Install the fuel pressure gauge.
3. Start the engine and idle at normal operating
temperature.
4. Disconnect the vacuum line going to the fuel
pressure regulator.
With the engine running, is the fuel pressure within the
specified range?
280-325 kPa
(41-46 psi)
Go to OBD
System
Check
Go to Step 6
6Check for restricted fuel lines or restricted in-line filter.
Was a problem found?
ÐVerify repairGo to Step 7
71. Ignition ªOFFº.
2. Remove the fuel pump relay and replace it with a
fused jumper which will connect the relay's battery
terminal to the terminal leading to the fuel pump
fuse.
3. While the fuel pump is operating, use pliers to slowly
close the return line (do not exceed the first
specified value).
Using the pliers to restrict the return line, can the fuel
pressure be manipulated to exceed the second
specified value?
325 kPa
(46 psi)
414 kPa
(60 psi)
Go to
Diagnostic
Aids
Go to Step 8
8Check for:

Faulty fuel pump

Restricted fuel pump strainer (sock)

Incorrect fuel pump

Incorrect fuel being used

Hot fuel
Is the action complete?
ÐVerify repairÐ

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±428
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
information included in the Failure Records data can
be useful in determined vehicle mileage since the
DTC was last set.
If it is determined that the DTC occurs intermittently,
performing the DTC
P1120 Diagnostic Chart may isolate the cause of the
fault.
DTC P1220-TPS 2 Circuit Fault

StepActionValue(s)Ye sNo
1Was the ªOn-Board (OBD) System Checkº performed?
ÐGo to Step 2
Go to OBD
System
Check
2Was the ªElectric Throttle Control (ETC) System
Checkº performed?
ÐGo to Step 3
Go to ETC
System
Check
31. Ignition ªONº, engine not running.
2. Observe the MAP reading on the Tech 2.
Is the MAP reading less than the specified value?
65 kPaGo to Step 4Go to Step 7
41. Disconnect the MAP sensor.
2. Connect a test 5 volt reference circuit and the MAP
signal at the MAP sensor harness connector.
3. Observe the MAP reading on the Tech 2.
Is the MAP reading less than the specified value? (If no,
start with diagnosis chart for other sensors in the circuit
and see if 5V returns.)
ÐGo to Step 6Go to Step 5
51. Check the MAP signal circuit between the PCM and
MAP ground circuit.
2. If the MAP signal circuit is open or shorted, repair as
necessary.
Was the MAP signal circuit open or shorted?
ÐVerify repairGo to Step 13
6Replace the MAP sensor.
Is the action complete?
ÐVerify repairÐ
7Observe the TP angle reading on the Tech-2 while
slowly opening the throttle.
Does the TP angle increase steadily and evenly from
the closed throttle value to the wide open throttle
value?Closed TPS1
8±10 % TPS2
8±10 % WTO
TPS1 90±92
% TPS2
90±92 %
Refer to
Diagnostic
Aids
Go to Step 8
81. Disconnect the TP sensor.
2. Observe the TP sensor reading on the Tech2.
Is the TP sensor reading near the specified value?
0VGo to Step 9Go to Step 10
91. Connect a test light between the 5Volt reference
circuit and the TP2 sensor signal circuit at the TP
sensor harness connector.
2. Observe the TP sensor reading on the Tech 2.
Is the TP sensor reading near the specified value?
5VGo to Step 12Go to Step 11

6E±429
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
DTC P1220-TPS 2 Circuit Fault

 
StepNo Ye s Value(s) Action
10Check the following items;
1. TP2 signal circuit for a short to voltage.
2. TP2 sensor ground circuit for high resistance
between the PCM and the TP2 sensor.
3. TP2 sensor ground circuit for a poor connection.
4. If a problem is found, repair wiring harness as
necessary.
Was a problem found?
ÐVerify repairGo to Step 13
11Check the following items;
1. TP2 signal circuit or 5 volt reference circuit for a
poor connection.
2. TP2 signal circuit or 5 volt reference circuit for high
resistance between the PCM and the TP sensor.
3. If a problem is found, repair wiring harness as
necessary.
Was a problem found?
ÐVerify repairGo to Step 13
12Replace the TP sensor.
Is the action complete?
ÐVerify repairÐ
13Replace the PCM.
IMPORTANT:The replacement PCM must be
programmed. Refer to
ON-Vehicle Service in Power
Control Module and Sensors for procedures.
And also refer to latest Service Bulletin. Check to see
if the latest software is released or not.
And then Down Load the LATEST PROGRAMMED
SOFTWARE to the replacement PCM.
Is the action complete?
ÐVerify repairÐ

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.

6E±431
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
7.Check the following circuits for accelerator pedal
problems. Check the following AP sensor
resistance.
9.Following DTC: Software detect Error for ETC
system.
10.Following DTC: Software detect Error for ETC
system.
Diagnostic Aids

An intermittent may be caused by a poor connection,
rubbed±through wire insulation or a wire broken insidethe insulation. Check for poor connections or a
damaged harness. Inspect the PCM harness and
connector for improper mating, broken locks,
improperly formed or damaged terminals, poor
terminal-to-wire connection, and damaged
harness.

Throttle body ± Check for objects blocking the DC
motor or throttle bore, excessive deposits in the ETC
passage and on the valve spring, and excessive
deposits in the throttle bore and on the throttle valve
plate.
Diagnosis Trouble Code(DTC)
P1221 TPS1 ± TPS2 Correlation(Circuit Performance)

StepActionValue(s)Ye sNo
1Was the ªOn-Board (OBD) System Checkº performed?
ÐGo to Step 2
Go to OBD
System
Check
2Was the ªElectric Throttle Control (ETC) System
Checkº performed?
ÐGo to Step 3
Go to ETC
System
Check
3Visually/physically inspect for the following conditions:

Throttle body tampering.

Restricted intake throttle 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
throttle passage or throttle bore, excessive
deposits in the throttle passage and on the
throttle valve, and excessive deposits in the
throttle bore and on the throttle plate.

Throttle body with lever: Check for objects send
round the throttle spring lever that lever is smooth
movement, and spring lever has not excessive
play
Do any of the above require a repair?
Ð
Refer to
appropriate
section for
on±vehicle
service
Go to Step 4
4Visually/physically inspect for the following conditions:

Accelerator pedal tampering.

Accelerator pedal : Check for objects blocking the
spring or pedal arm.

Accelerator pedal : Check for objects move the
accelerator pedal that pedal is smooth
movement, and accelerator pedal arm has not
excessive play.
Do any of the above require a repair?
Ð
Refer to
appropriate
section for
on±vehicle
service
Go to Step 5
51. Check for a poor connection at the throttle body
harness connector.
2. Check for a poor connection at the accelerator
position sensor harness connector.
3. If a problem is found, replace faulty terminals as
necessary.
Was a problem found?
ÐVerify repairGo to Step 6

6E±432
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Diagnosis Trouble Code(DTC)
P1221 TPS1 ± TPS2 Correlation(Circuit Performance)

 
StepNo Ye s Value(s) Action
61. Check the following circuits for an open, short to
voltage, short to ground, or poor connection at the
PCM:
Throttle position sensor 1 circuit.
Throttle position sensor 2 circuit.
Throttle DC motor circuit.
Throttle position sensor resistance.
Throttle DC motor resistance.
2. If a problem is found, repair as necessary.
Was a problem found?
Vcc-GND
1±7k

SIG-GND
change
resistance 0.3
± 100

Verify repairGo to Step 7
71. Check the following circuits for an open, short to
voltage, short to ground, or poor connection at the
PCM:

Accelerator position sensor 1 circuit.

Accelerator position sensor 2 circuit.

Sensor 3 circuit.

Sensor resistance.
2. If a problem is found, repair as necessary.
Was a problem found?
Vcc-GND
1±7k

SIG-GND
change
resistance 0.3
± 100

Verify repairGo to Step 8
8Replace the accelerator position sensor.
Is the action complete?
ÐGo to Step 9Ð
9Stored DTCs;
P1125, P1290, P1295, P1299
Ð
Go to
applicable
DTC table
Go to Step 10
10Stored DTCs;
P1514, P1515, P1516, P1523, P1271, P1272, P1273
Ð
Go to
applicable
DTC table
Go to Step 11
11Replace the PCM.
IMPORTANT:The replacement PCM must be
programmed.
Refer to
ON-Vehicle Service in Power Control Module
and Sensors for procedures.
And also refer to latest Service Bulletin.
Check to see if the latest software is released or not.
And then Down Load the LATEST PROGRAMMED
SOFTWARE to the replacement PCM.
Is the action complete?
ÐVerify repairÐ