DTC ISUZU AXIOM 2002 Service Manual PDF

6E±43
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Menu

The following table shows which functions are used
for the available equipment versions.
060R100018
DTC Modes
060R100077
On OBD II vehicles there are options available in Tech 2
DTC mode to display the enhanced information available.
After selecting DTC, the following menu appears:
1. Read DTC Info by Priority
2. Freeze Frame
3. Fail Records (not all applications)
4. DTC Info
5. Clear Info
060RW223
The following is a brief description of each of the sub
menus in DTC Info and DTC. The order in which they
appear here is alphabetical and not necessarily the way
they will appear on the Tech 2.
DTC Information Mode
Use the DTC info mode to search for a specific type of
stored DTC information.
DTC Status
This selection will display any DTCs that have not run
during the current ignition cycle or have reported a test
failure during this ignition up to DTCs. DTC tests which
run and pass will cause that DTC number to be removed
from Tech 2 screen.
Fail This Ignition
This selection will display all DTCs that have failed during
the present ignition cycle.
History
This selection will display only DTCs that are stored in the
PCM's history memory. It will display all type A and B
DTCs that have requested the MIL and have failed within
the last 40 warm-up cycles. In addition, it will display all
type C and type D DTCs that have failed within the last 40
warm-up cycles.
Last Test Failed
This selection will display only DTCs that have failed the
last time the test run. The last test may have run during a
previous ignition cycle if a type A or type B DTC is
displayed. For type C and type D DTCs, the last failure
must have occurred during the current ignition cycle to
appear as Last Test Fail.
MILSVC or Message Request
This selection will display only DTCs that are requesting
the MIL. Type C and type D DTCs cannot be displayed
using this option. This selection will report type B DTCs
only after the MIL has been requested.

6E±44
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Not Run Since Code Cleared
This option will display up to DTCs that have not run since
the DTCs were last cleared. Since any displayed DTCs
have not run, their condition (passing or failing) is
unknown.
Test Failed Since Code Cleared
This selection will display all active and history DTCs that
have reported a test failure since the last time DTCs were
cleared. DTCs that last failed more than 40 warm-up
cycles before this option is selected will not be displayed.
Miscellaneous Test
This test consists of eight menus-Lights, Relays, EVAP,
Fuel System, Instruments, EGR Control, Variable Intake
Manifold Solenoid, and Injector Balance Tests.
In these tests, Tech 2 sends operating signals to the
systems to confirm their operations thereby to judge the
normality of electric circuits.
To judge intermittent trouble,
1. Confirm DTC freeze frame data, and match the
freeze frame data as test conditions with the data list
displayed by Miscellaneous Test.
2. Confirm DTC setting conditions, and match the
setting conditions as test conditions with the data list
displayed by Miscellaneous Test.
3. Refer to the latest Service Bulletin.
Check to see if the Latest software is released or not.
Down load the LATEST PROGRAMMED
SOFTWARE to the replacement PCM.
Lamps Test
This test is conducted check MIL, Up Shift Lamp, Low
Fuel Lamp, Reduced Power Lamp and Cruise Control
Lamp for its working.
Tech2 must be used for this test.
Test Procedure:
1. Connect Tech 2 to the vehicle DLC.
2. Run the Engine at idle.
3. Select F3: Miscellaneous Test in the Application
Menu.
060R100078
4. Select F0:Lamps Test in the Miscellaneous Test.
060RY00080
5. Select F0:Malfunction Indicator Lamp.
060RY00091
6. PushºOnº soft key.
7. Make sure Lamp illuminates.
8. If lamp illuminates, the Lamp is operating correctly.

6E±58
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS

For the 3.5L w/automatic transmission, the
pre-catalyst sensors are designated Bank 1 HO2S 1
and Bank 2 HO2S 1. The post-catalyst sensors are
Bank 1 HO2S 2 and Bank 2 HO2S 2.
Catalyst Monitor Outputs
The catalyst monitor diagnostic is sensitive to the
following conditions:

Exhaust leaks

HO2S contamination

Alternate fuels
Exhaust system leaks may cause the following:

Preventing a degraded catalyst from failing the
diagnostic.

Causing a false failure for a normally functioning
catalyst.

Preventing the diagnostic from running.
Some of the contaminants that may be encountered are
phosphorus, lead, silica, and sulfur. The presence of
these contaminants will prevent the TWC diagnostic from
functioning properly.
Three-Way Catalyst Oxygen Storage Capacity
The Three-Way catalyst (TWC) must be monitored for
efficiency. To accomplish this, the control module
monitors the pre-catalyst HO2S and post-catalyst HO2S
oxygen sensors. When the TWC is operating properly,
the post-catalyst oxygen sensor will have significantly
less activity than the pre-catalyst oxygen sensor. The
TWC stores and releases oxygen as needed during its
normal reduction and oxidation process. The control
module will calculate the oxygen storage capacity using
the difference between the pre-catalyst and post catalyst
oxygen sensor's voltage levels. If the activity of the
post-catalyst oxygen sensor approaches that of the
pre-catalyst oxygen sensor, the catalyst's efficiency is
degraded.
Stepped or staged testing level allow the control module
to statistically filter test information. This prevents falsely
passing or falsely failing the oxygen storage capacity test.
The calculations performed by the on-board diagnostic
system are very complex. For this reason, post catalyst
oxygen sensor activity should not be used to determine
oxygen storage capacity unless directed by the service
manual.
Two stages are used to monitor catalyst efficiency.
Failure of the first stage will indicate that the catalyst
requires further testing to determine catalyst efficiency.
The seconds stage then looks at the inputs for the pre and
post catalyst HO2S sensors more closely before
determining if the catalyst is indeed degraded. This
further statistical processing is done to increase the
accuracy of oxygen storage capacity type monitoring.
Failing the first (stage 1) test DOES NOT indicate a failed
catalyst. The catalyst may be marginal or the fuel sulfur
content could be very high.Aftermarket HO2S characteristics may be different from
the original equipment manufacturer sensor. This may
lead to a false pass or a false fail of the catalyst monitor
diagnostic. Similarly, if an aftermarket catalyst does not
contain the same amount of cerium as the original part,
the correlation between oxygen storage and conversion
efficiency may be altered enough to set a false DTC.
Misfire Monitor Diagnostic Operation
Misfire Monitor Diagnostic Operation
Misfire is monitored as a function of the combustion
quality (CQ) signals generated from the ignition current
sense system. Combustion signals represent the degree
of combustion in each cylinder. Misfire is detected when
the combustion signal is below a predetermined value.
The misfire ratio is calculated once every 100 engine
cycles. For example, on a 6-cylinder engine, 600 ignition
plug sparks occur every 100 cycles and if a misfire occurs
12 times during that time, the misfire is 12/600 y 100 = 2
%.
Misfire Counters
Whenever a cylinder misfires, the misfire diagnostic
counts the misfire and notes the crankshaft position at the
time the misfire occurred. These ªmisfire countersº are
basically a file on each engine cylinder. A current and a
history misfire counter are maintained for each cylinder.
The misfire current counters (Misfire Cur #1-6) indicate
the number of firing events out of the last 100 cylinder
firing events which were misfires. The misfire current
counter will display real time data without a misfire DTC
stored. The misfire history counters (Misfire Hist #1-6)
indicate the total number of cylinder firing events which
were misfires. The misfire history counters will display 0
until the misfire diagnostic has failed and a DTC P0300 is
set. Once the misfire DTC P0300 is set, the misfire
history counters will be updated every 100 cylinder firing
events. A misfire counter is maintained for each cylinder.
If the misfire diagnostic reports a failure, the diagnostic
executive reviews all of the misfire counters before
reporting DTC. This way, the diagnostic executive
reports the most current information.
When crankshaft rotation is erratic, a misfire condition will
be detected. Because of this erratic condition, the data
that is collected by the diagnostic can sometimes
incorrectly identify which cylinder is misfiring. Misfires are
counted from more than one cylinder. Cylinder #1 has the
majority of counted misfires. In this case, the Misfire
Counters would identify cylinder #1 as the misfiring
cylinder. The misfires in the other counters were just
background noise caused by the erratic misfire rotation of
the crankshaft. If the number of accumulated misfires is
sufficient for the diagnostic to identify a true misfire, the
diagnostic will set DTC P0300 ± Misfire Detected.
Use diagnostic equipment to monitor misfire counter data
on OBD II-compliant vehicles. Knowing which specific
cylinder(s) misfired can lead to the root cause, even when
dealing with a multiple cylinder misfire. Using the
information in the misfire counters, identify which
cylinders are misfiring. If the counter indicate cylinders

6E±59
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
numbers 1 and 4 misfired, look for a circuit or component
common to both cylinders number 1 and 4.
Misfire counter information is located in the ªEngº. menu,
ªMisfire Dataº sub-menu of the data list.
The misfire diagnostic may indicate a fault due to a
temporary fault not necessarily caused by a vehicle
emission system malfunction. Examples include the
following items:

Contaminated fuel

Low fuel

Fuel-fouled spark plugs

Basic engine fault
Fuel Trim System Monitor Diagnostic
Operation
Fuel Trim System Monitor Diagnostic
Operation
This system monitors the averages of short-term and
long-term fuel trim values. If these fuel trim values stay at
their limits for a calibrated period of time, a malfunction is
indicated. The fuel trim diagnostic compares the
averages of short-term fuel trim values and long-term fuel
trim values to rich and lean thresholds. If either value is
within the thresholds, a pass is recorded. If both values
are outside their thresholds, a rich or lean DTC will be
recorded.
The fuel trim system diagnostic also conducts an intrusive
test. This test determines if a rich condition is being
caused by excessive fuel vapor from the EVAP canister.
In order to meet OBD II requirements, the control module
uses weighted fuel trim cells to determine the need to set
a fuel trim DTC. A fuel trim DTC can only be set if fuel trim
counts in the weighted fuel trim cells exceed
specifications. This means that the vehicle could have a
fuel trim problem which is causing a problem under
certain conditions (i.e., engine idle high due to a small
vacuum leak or rough idle due to a large vacuum leak)
while it operates fine at other times. No fuel trim DTC
would set (although an engine idle speed DTC or HO2S
DTC may set). Use the Tech 2 to observe fuel trim counts
while the problem is occurring.
A fuel trim DTC may be triggered by a number of vehicle
faults. Make use of all information available (other DTCs
stored, rich or lean condition, etc.) when diagnosing a fuel
trim fault.
Fuel Trim Cell Diagnostic Weights
No fuel trim DTC will set regardless of the fuel trim counts
in cell 0 unless the fuel trim counts in the weighted cells
are also outside specifications. This means that the
vehicle could have a fuel trim problem which is causing a
problem under certain conditions (i.e. engine idle high due
to a small vacuum leak or rough due to a large vacuum
leak) while it operates fine at other times. No fuel trim
DTC would set (although an engine idle speed DTC or
HO2S DTC may set). Use the Tech 2 to observe fuel trim
counts while the problem is occurring.

6E±60
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
On-Board Diagnostic (OBD II) System Check
060R200048
Circuit Description
The on-board diagnostic system check is the starting
point for any driveability complaint diagnosis. Before
using this procedure, perform a careful visual/physical
check of the PCM and engine grounds for cleanliness and
tightness.
The on-board diagnostic system check is an organized
approach to identifying a problem created by an
electronic engine control system malfunction.
Diagnostic Aids
An intermittent may be caused by a poor connection,
rubbed±through wire insulation or a wire broken inside the
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.
Test Description
Number(s) below refer to the step number(s) on the
Diagnostic Chart:
1.The MIL (ªCheck Engine lampº) should be ªONº
steady with the ignition ªON º and the engine ªOFFº.
If not, the ªNo MILº chart should be used to isolate
the malfunction.
2.The RPL (ªReduced Power lampº) should be ªONº
steady with the ignition ªON ºand the engine ªOFFº.
If not, the ªNo RPLºchart should be used to isolate
the malfunction.3.Checks the Class 2 data circuit and ensures that the
PCM is able to transmit serial data.
4.This test ensures that the PCM is capable of
controlling the MIL (ªCheck Engine lampº) and the
MIL (ªCheck Engine lampº) driver circuit is not
shorted to ground.
5.This test ensures that the PCM is capable of
controlling the RPL (ªReduced Power lampº) and
the RPL (ªReduced Power lampº) driver circuit is not
shorted to ground.
7.Check the DTCs (System ,Volts Supply circuit).
8.Check the DTCs (PCM{Software} detect Errors).
11.If the engine will not start, the Cranks But Will Not
Run chart should be used to diagnose the condition.
14.A Tech 2 parameter which is not within the typical
range may help to isolate the area which is causing
the problem.
15.This vehicle is equipped with a PCM which utilizes
an electrically erasable programmable read only
memory (EEPROM). When the PCM is replaced,
the new PCM must be programmed. Refer to PCM
Replacement and Programming Procedures in
Powertrain Control Module (PCM) and Sensors
of
this section.
10. If the starter motor will not start, the starter control
system chart should be used to diagnose the
condition.

6E±61
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
On-Board Diagnostic (OBD II) System Check

StepActionValue(s)Ye sNo
11. Ignition ªONº, engine ªOFFº.
2. Observe the malfunction indicator lamp (MIL or
ªCheck Engine lampº).
Is the MIL (ªCheck Engine lampº)ªONº?
ÐGo to Step 2
Go to No
MIL(ªCheck
Engine lampº)
21. Ignition ªONº, engine ªOFFº.
2. Observe the ªReduced Power lampº.
Is the RPL (ªReduced Power lampº) ªONº?
ÐGo to Step 3
Go to No
RPL(ªReduce
d Power
lampº)
31. Ignition ªOFFº.
2. Install Tech 2.
3. Ignition ªONº.
4. Attempt to display PCM engine data with the
Tech 2.
Does the Tech 2 display PCM data?
ÐGo to Step 4Go to Step 12
41. Using the Tech 2 output tests function, select MIL
(ªCheck Engine lampº) control and command the
MIL (ªCheck Engine Lampº) ªOFFº.
2. Observe the MIL (ªCheck Engine lampº).
Did the MIL (ªCheck Engine lampº) turn ªOFFº?
ÐGo to Step 5
Go to
MIL(ªCheck
Engine lampº)
On Steady
51. Using the Tech 2 output tests function, select MIL
(ªCheck Engine lampº) control and command the
RPL (ªReduced Power lampº) ªOFFº.
2. Observe the RPL (ªReduced Power lampº).
Did the MIL (ªReduced Power lampº) turn ªOFFº?
ÐGo to Step 6
Go to
RPL(ªReduce
d Power
lampº) On
Steady
6Select ªDisplay DTCsº with the Tech 2.
Are any DTCs stored?
ÐGo to Step 7Go to Step 11
7Stored DTCs.
P0562, P0563, P0601, P0602, P0604, P0606, P1625,
P1635, P1639, P1640, P1650
Are the applicable DTCs stored?
Ð
Go to
applicable
DTC table
Go to Step 8
8Stored DTCs.
P1514, P1515, P1516, P1523, P1125, P1290, P1295,
P1299
Are the applicable DTCs stored?
Ð
Go to
applicable
DTC table
Go to Step 9
9Stored DTCs.
1. P0425, P0106, P0107, P1107, P0401, P1404,
P0405, P1120, P1221, P1515, P1516, P1275,
P1635, P1271, P1273, P1285, P1272
2. P0336, P0337, P1220, P1515, P1221, P1516,
P1280, P1639, P1271, P1272
Are the applicable DTCs stored?
Ð
Go to
ªMultiple
PCM
Information
sensor DTCs
Setº
Go to Step 10
10Attempt to crank the starter motor
Did the starter motor crank?
ÐGo to Step 10
Go to Starter
control
system
11Attempt to start the engine.
Did the engine start and continue to run?
ÐGo to Step 6
Go to Cranks
But Will Not
Run

6E±64
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
A/C Clutch Diagnosis
This chart should be used for diagnosing the electrical
portion of the A/C compressor clutch circuit. A Tech 2 will
be used in diagnosing the system. The Tech 2 has the
ability to read the A/C request input to the PCM. The
Tech 2 can display when the PCM has commanded the
A/C clutch ªONº. The Tech 2 should have the ability to
override the A/C request signal and energize the A/C
compressor relay.
Test Description
IMPORTANT:Do not engage the A/C compressor
clutch with the engine running if an A/C mode is not
selected at the A/C control switch.
The numbers below refer to the step numbers on the
Diagnostic Chart:3. This a test determine is the problem is with the
refrigerant system. If the switch is open, A/C
pressure gauges will be used to determine if the
pressure switch is faulty or if the system is partially
discharged or empty.
4. Although the normal complaint will be the A/C clutch
failing to engage, it is possible for a short circuit to
cause the clutch to run when A/C has not been
selected. This step is a test for that condition.
7. There is an extremely low probability that both relays
will fail at the same time, so the substitution process
is one way to check the A/C Thermostat relay. Use
a known good relay to do a substitution check.
A/C Clutch Control Circuit Diagnosis

StepActionValue(s)Ye sNo
1Was the ªOn-Board Diagnostic (OBD) System Checkº
performed?
ÐGo to Step 2
Go to OBD
System
Check
2Are any other DTCs stored?
Ð
Go to the
other DTC
chart(s) first
Go to Step 3
31. Disconnect the electrical connector at the pressure
switch located on the receiver/drier.
2. Use an ohmmeter to check continuity across the
pressure switch.
Is the pressure switch open?
Ð
Go to Air
Conditioning
to diagnose
the cause of
the open
pressure
switch
Go to Step 4
4IMPORTANT:Before continuing with the diagnosis, the
following conditions must be met:

The intake air temperature must be greater than
15
C. (60
F).

The engine coolant temperature must be less
than 119
C (246
F).
1. A/C ªOFFº.
2. Start the engine and idle for 1 minute.
3. Observe the A/C compressor.
Is the A/C compressor clutch engaged even though
A/C has not been requested?
ÐGo to Step 37Go to Step 5
51. Idle the engine.
2. A/C ªONº.
3. Blower ªONº.
4. Observe the A/C compressor.
Is the A/C compressor magnetic clutch engaged?
Ð
Refer to
Diagnostic
Aids
Go to Step 6
61. Engine idling.
2. A/C ªONº.
3. Blower ªONº.
4. Observe the ªA/C Requestº display on the Tech 2.
(Refer to the Miscellaneous test)
Does the tool ªA/C Requestº display indicate ªYesº?
ÐGo to Step 26Go to Step 7

6E±68
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Electronic Ignition System Diagnosis
If the engine cranks but will not run or immediately stalls,
the Engine Cranks But Will Not Start chart must be used
to determine if the failure is in the ignition system or the
fuel system. If DTC P0300 through P0306, P0341, or
P0336 is set, the appropriate diagnostic trouble code
chart must be used for diagnosis.
If a misfire is being experienced with no DTC set, refer to
the
Symptoms section for diagnosis.
EVAP Canister Purge Solenoid and
EVAP Vent Solenoid Valve
A continuous purge condition with no purge commanded
by the PCM will set a DTC P1441. Refer to the DTC charts
for further information.
Visual Check of The Evaporative
Emission Canister

If the canister is cracked or damaged, replace the
canister.

If fuel is leaking from the canister, replace the canister
and check hoses and hose routing.
Fuel Metering System Check
Some failures of the fuel metering system will result in an
ªEngine Cranks But Will Not Runº symptom. If this
condition exists, refer to the
Cranks But Will Not Run
chart. This chart will determine if the problem is caused
by the ignition system, the PCM, or the fuel pump
electrical circuit.
Refer to
Fuel System Electrical Test for the fuel system
wiring schematic.
If there is a fuel delivery problem, refer to
Fuel System
Diagnosis
, which diagnoses the fuel injectors, the fuel
pressure regulator, and the fuel pump. If a malfunction
occurs in the fuel metering system, it usually results in
either a rich HO2S signal or a lean HO2S signal. This
condition is indicated by the HO2S voltage, which causes
the PCM to change the fuel calculation (fuel injector pulse
width) based on the HO2S reading. Changes made to the
fuel calculation will be indicated by a change in the long
term fuel trim values which can be monitored with a
Tech 2. Ideal long term fuel trim values are around 0%;
for a lean HO2S signal, the PCM will add fuel, resulting in
a fuel trim value above 0%. Some variations in fuel trim
values are normal because all engines are not exactly the
same. If the evaporative emission canister purge is ªONº,
the fuel trim may be as low as ±38%. If the fuel trim values
are greater than +23%, refer to
DTC P0131, DTC P0151,
DTC P0171, and DTC 1171
for items which can cause a
lean HO2S signal.
Fuel System Pressure Test
A fuel system pressure test is part of several of the
diagnostic charts and symptom checks. To perform this
test, refer to
Fuel Systems Diagnosis.
Fuel Injector Coil Test Procedure and
Fuel Injector Balance Test Procedure
T32003
Test Description
Number(s) below refer to the step number(s) on the
Diagnostic Chart:
2. Relieve the fuel pressure by connecting the J
34730-1 Fuel Pressure Gauge to the fuel pressure
connection on the fuel rail.
CAUTION: In order to reduce the risk of fire and
personal injury, wrap a shop towel around the fuel
pressure connection. The towel will absorb any fuel
leakage that occurs during the connection of the fuel
pressure gauge. Place the towel in an approved
container when the connection of the fuel pressure
gauge is complete.
Place the fuel pressure gauge bleed hose in an
approved gasoline container.
With the ignition switch ªOFFº, open the valve on the
fuel pressure gauge.
3. Record the lowest voltage displayed by the DVM
after the first second of the test. (During the first
second, voltage displayed by the DVM may be
inaccurate due to the initial current surge.)
Injector Specifications:
Resistance (Ohms)
Voltage Specification at
10
C-35
C (50
F-95
F)
11.8 ± 12.65.7 ± 6.6

The voltage displayed by the DVM should be within
the specified range.

The voltage displayed by the DVM may increase
throughout the test as the fuel injector windings
warm and the resistance of the fuel injector windings
changes.

6E±73
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Powertrain Control Module (PCM)
Diagnosis
To read and clear diagnostic trouble codes, use a Tech 2.
IMPORTANT:Use of a Tech 2 is recommended to clear
diagnostic trouble codes from the PCM memory.
Diagnostic trouble codes can also be cleared by turning
the ignition ªOFFº and disconnecting the battery power
from the PCM for 30 seconds. Turning off the ignition and
disconnecting the battery power from the PCM will cause
all diagnostic information in the PCM memory to be
cleared. Therefore, all the diagnostic tests will have to be
re-run.
Since the PCM can have a failure which may affect only
one circuit, following the diagnostic procedures in this
section will determine which circuit has a problem and
where it is.
If a diagnostic chart indicates that the PCM connections
or the PCM is the cause of a problem, and the PCM is
replaced, but this does not correct the problem, one of the
following may be the reason:

There is a problem with the PCM terminal
connections. The terminals may have to be removed
from the connector in order to check them properly.

EEPROM program is not correct for the application.
Incorrect components or reprogramming the PCM
with the wrong EEPROM program may cause a
malfunction and may or may not set a DTC.

The problem is intermittent. This means that the
problem is not present at the time the system is being
checked. In this case, refer to the
Symptoms portion
of the manual and make a careful physical inspection
of all component and wiring associated with the
affected system.

There is a shorted solenoid, relay coil, or harness.
Solenoids and relays are turned ªONº and ªOFFº by
the PCM using internal electronic switches called
drivers. A shorted solenoid, relay coil, or harness will
not damage the PCM but will cause the solenoid or
relay to be inoperative.
Multiple PCM Information Sensor
DTCs Set
Circuit Description
The powertrain control module (PCM) monitors various
sensors to determine the engine operating conditions.
The PCM controls fuel delivery, spark advance,
transmission operation, and emission control device
operation based on the sensor inputs.
The PCM provides a sensor ground to all of the sensors.
The PCM applies 5 volts through a pull±up resistor, and
determines the status of the following sensors by
monitoring the voltage present between the 5±volt supply
and the resistor:

The engine coolant temperature (ECT) sensor

The intake air temperature (IAT) sensor

The transmission fluid temperature (TFT) sensorThe PCM provides the following sensors with a 5±volt
reference and a sensor ground signal:
1

The exhaust gas recirculating (EGR) pintle position
sensor

The manifold absolute pressure (MAP) sensor

The throttle position (TP) sensor 1

The acceleration position (AP) sensor 1

The acceleration position (AP) sensor 3

The Vapor Pressure Sensor
2

The Crank position (CKP) sensor

The throttle position (TP) sensor 2

The acceleration position (AP) sensor 2
The PCM monitors the separate feedback signals from
these sensors in order to determine their operating
status.
Diagnostic Aids
IMPORTANT:Be sure to inspect PCM and engine
grounds for being secure and clean.
A short to voltage in one of the sensor input circuits may
cause one or more of the following DTCs to be set:

P0425

P0108, P1106

P0406

P1120, P1515, P1221, P1516, P1635

P1275, P1639, P1271, P1273

P1285, P1272, P1273

P0336, P0337

P1220, P1515, P1221, P1515, P1516

P1280, P1271, P1272
IMPORTANT:If a sensor input circuit has been shorted
to voltage, ensure that the sensor is not damaged. A
damaged sensor will continue to indicate a high or low
voltage after the affected circuit has been repaired. If the
sensor has been damaged, replace it.
An open in the sensor ground circuit between the PCM
and the splice will cause one or more of the following
DTCs to be set:

P0425

P0108, P1106

P0406

P1120, P1515, P1221, P1516, P1635

P1275, P1639, P1271, P1273

P1285, P1272, P1273

P0336, P0337

P1220, P1515, P1221, P1515, P1516

P1280, P1271, P1272
A short to ground in the 5±volt reference A or B circuit will
cause one or more of the following DTCs to be set:

P0453

P0106, P0107, P1107

P0401, P1404, P0405

P1120, P1515, P1221, P1516, P1635

6E±74
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS

P1275, P1639, P1271, P1273

P1285, P1272, P1273

P0336, P0337

P1220, P1515, P1221, P1515, P1516

P1280, P1271, P1272
Check for the following conditions:

Poor connection at PCM. Inspect the harness
connectors for backed±out terminals, improper
mating, broken locks, improperly formed or damage
terminals, and a poor terminal±to±wire connection.
Damaged harness. Inspect the wiring harness for
damage. If the harness is not damaged, observe an
affected sensor fs displayed value on the Tech 2 with
the ignition ªONº and the engine ªOFFº while you
move the connectors and the wiring harnesses
related to the following sensors:

Vapor Pressure (Fuel Tank Pressure) Sensor

MAP Sensor

EGR

TPS1/TPS2

APS1/APS2/APS3

CKP
Multiple PCM Information Sensor DTCs Set

StepActionValue(s)Ye sNo
1Was the ªOn-Board (OBD) System Checkº performed?
ÐGo to Step 2
Go to OBD
System
Check
21. Turn the ignition ªOFFº, disconnect the PCM.
2. Turn the ignition ªONº, check the 5 volt reference 1
and 2 circuit for the following conditions:

A poor connection at the PCM.

An open between the PCM connector and the
splice.

A short to ground.

A short to voltage.
Is there an open or short?
ÐGo to Step 3Go to Step 4
3Repair the open or short.
Is the action complete?
ÐVerify repairÐ
4Check the sensor ground circuit for the following
conditions:

A poor connection at the PCM or the affected
sensors.

An open between the PCM connector and the
affected sensors.
Is there an open or a poor connection?
ÐGo to Step 5Go to Step 6
5Repair the open or the poor connection.
Is the action complete?
ÐVerify repairÐ
6Following below the DTCs stored:
P1635, P1639
Ð
Go to
applicable
DTC table
Go to Step 7
7 Measure the resistance below the items:

Between EGR sensor supply circuit and Vapor
Pressure Sensor supply circuit.

Between MAP sensor supply circuit and Vapor
Pressure Sensor supply circuit.

Between Vapor Pressure Sensor supply circuit
and PCM harness connector. (5Volt supply
circuit)
Is the resistance near the specified value?
ÐGo to Step 9Go to Step 8