Emissions drive cycle ISUZU AXIOM 2002 Service Repair Manual

6E±1
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
AXIOM
ENGINE
6VE1 3.5L ENGINE
DRIVEABILITY AND EMISSIONS
CONTENTS
Specifications 6E±6. . . . . . . . . . . . . . . . . . . . . . . . . . .
Tightening Specifications 6E±6. . . . . . . . . . . . . . .
Diagrams and Schematics 6E±7. . . . . . . . . . . . . . . .
PCM Wiring Diagram (1 of 7) 6E±7. . . . . . . . . . . .
PCM Wiring Diagram (2 of 7) 6E±8. . . . . . . . . . . .
PCM Wiring Diagram (3 of 7) 6E±9. . . . . . . . . . . .
PCM Wiring Diagram (4 of 7) 6E±10. . . . . . . . . . . .
PCM Wiring Diagram (5 of 7) 6E±11. . . . . . . . . . . .
PCM Wiring Diagram (6 of 7) 6E±12. . . . . . . . . . . .
PCM Wiring Diagram (7 of 7) 6E±13. . . . . . . . . . . .
PCM Pinouts 6E±14. . . . . . . . . . . . . . . . . . . . . . . . . . .
PCM Pinout Table, 80-Way Blue Connector
± Row ªF1 ~ 20º 6E±14. . . . . . . . . . . . . . . . . . . . . .
PCM Pinout Table, 80-Way Blue Connector
± Row ªF20 ~ 40º 6E±15. . . . . . . . . . . . . . . . . . . . .
PCM Pinout Table, 80-Way Blue Connector
± Row ªF41 ~ 60º 6E±16. . . . . . . . . . . . . . . . . . . . .
PCM Pinout Table, 80-Way Blue Connector
± Row ªF61 ~ 80º 6E±17. . . . . . . . . . . . . . . . . . . . .
PCM Pinout Table, 80-Way Red Connector
± Row ªS1 ~ 20º 6E±19. . . . . . . . . . . . . . . . . . . . . .
PCM Pinout Table, 80-Way Red Connector
± Row ªS21 ~ 40º 6E±21. . . . . . . . . . . . . . . . . . . . .
PCM Pinout Table, 80-Way Red Connector
± Row ªS41 ~ 60º 6E±23. . . . . . . . . . . . . . . . . . . . .
PCM Pinout Table, 80-Way Red Connector
± Row ªS61 ~ 80º 6E±25. . . . . . . . . . . . . . . . . . . . .
Component Locators 6E±27. . . . . . . . . . . . . . . . . . .
Undercarriage Component Locator 6E±29. . . . . .
Fuse and Relay Panel (Underhood
Electrical Center) 6E±30. . . . . . . . . . . . . . . . . . . . .
Sensors and Miscellaneous Component
Locators 6E±31. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Diagnosis 6E±33. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Strategy-Based Diagnostics 6E±33. . . . . . . . . . . . .
DTC Stored 6E±33. . . . . . . . . . . . . . . . . . . . . . . . . . .
No DTC 6E±33. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
No Matching Symptom 6E±33. . . . . . . . . . . . . . . . .
Intermittents 6E±33. . . . . . . . . . . . . . . . . . . . . . . . . .
No Trouble Found 6E±33. . . . . . . . . . . . . . . . . . . . .
Verifying Vehicle Repair 6E±33. . . . . . . . . . . . . . . .
General Service Information 6E±33. . . . . . . . . . . . . .
OBD II Serviceablity Issues 6E±33. . . . . . . . . . . . .
Emissions Control Information Label 6E±34. . . . .
Visual / Physical Engine Compartment
Inspection 6E±34. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Basic Knowledge of Tools Required 6E±35. . . . . .
Serial Data Communications 6E±35. . . . . . . . . . . . . . Class 2 Serial Data Communications 6E±35. . . . .
On-Board Diagnostic (OBD II) 6E±35. . . . . . . . . . . . .
On-Board Diagnostic Tests 6E±35. . . . . . . . . . . . .
Comprehensive Component Monitor
Diagnostic Operation 6E±35. . . . . . . . . . . . . . . . . .
System Status and Drive Cycle for
Satisfying Federal Inspection/Maintenance
(I/M 240) Regulations 6E±36. . . . . . . . . . . . . . . . . .
Common OBD II Terms 6E±36. . . . . . . . . . . . . . . . .
The Diagnostic Executive 6E±36. . . . . . . . . . . . . . .
DTC Types 6E±37. . . . . . . . . . . . . . . . . . . . . . . . . . .
Decimal/Binary/Hexadecimal Conversions 6E±39
Verifying Vehicle Repair 6E±39. . . . . . . . . . . . . . . .
Reading Diagnostic Trouble Codes Using
The Tech 2 Scan Tool 6E±39. . . . . . . . . . . . . . . . .
Tech 2 6E±40. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Tech 2 Features 6E±41. . . . . . . . . . . . . . . . . . . . . . .
Getting Started 6E±41. . . . . . . . . . . . . . . . . . . . . . . .
Operating Procedure (For Example) 6E±42. . . . .
DTC Modes 6E±43. . . . . . . . . . . . . . . . . . . . . . . . . . .
DTC Information Mode 6E±43. . . . . . . . . . . . . . . . .
Miscellaneous Test 6E±44. . . . . . . . . . . . . . . . . . . .
Lamps Test 6E±44. . . . . . . . . . . . . . . . . . . . . . . . . . .
Relays Test 6E±46. . . . . . . . . . . . . . . . . . . . . . . . . . .
EVAP Test 6E±47. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fuel System Test 6E±48. . . . . . . . . . . . . . . . . . . . . .
Instruments Test 6E±50. . . . . . . . . . . . . . . . . . . . . . .
EGR Control Test 6E±52. . . . . . . . . . . . . . . . . . . . . .
Variable Intake Manifold Solenoid Test 6E±52. . .
Injector Balance Test 6E±54. . . . . . . . . . . . . . . . . . .
Plotting Snapshot Graph 6E±54. . . . . . . . . . . . . . . . .
Plotting Graph Flow Chart (Plotting graph
after obtaining vehicle information) 6E±55. . . . . .
Flow Chart for Snapshot Replay (Plotting
Graph) 6E±56. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Primary System-Based Diagnostic 6E±57. . . . . . . . .
Primary System-Based Diagnostic 6E±57. . . . . . .
Fuel Control Heated Oxygen Sensor 6E±57. . . . .
HO2S Heater 6E±57. . . . . . . . . . . . . . . . . . . . . . . . .
Catalyst Monitor Heated Oxygen Sensors
and Diagnostic Operation 6E±57. . . . . . . . . . . . . .
Misfire Monitor Diagnostic Operation 6E±58. . . . . . .
Misfire Monitor Diagnostic Operation 6E±58. . . . .
Misfire Counters 6E±58. . . . . . . . . . . . . . . . . . . . . . .

6E±16
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
PCM Pinout Table, 80-Way Blue Connector ± Row ªF41 ~ 60º
060RY00046
PINPIN FunctionWire ColorIGN ONENG RUNRefer To
F41Throttle Position(TP) 1
Sensor GroundGRN0.0V0.0VGeneral Description and
Operation, TPS
F42Fuel Pump RelayPNK/WHT0.0VB+On Vehicle Service, Fuel
Pump Relay
F43Adaptor CaseVIO/RED0.0V0.0V4L30E T/Mission
F44Bank 1 HO2S 2 Heater
GroundORN/WHT0.0V0.0VGeneral Description and
Operation, Catalyst Monitor
HO2S 2
F45A/C RequestGRN/BLK0.0V0.0VChassis Electrical
F46Stop Lamp SwitchBRN/RED0.0V0.0VChassis Electrical
F47Adaptor CaseVIO/WHTB+B+4L30E T/Mission
F48Throttle Valve DC Motor(±:
REV)BLUDuty CycleDuty CycleGeneral Description and
Operation, ETC
F49Not UsedÐÐÐÐ
F50Bank 2 HO2S 2 GroundORN0.0V0.0VÐ
F51Not UsedÐÐÐÐ
F52Bank 1 HO2S 2 GroundRED0.0V0.0VÐ
F53ECT GroundYEL/BLK0.0V0.0VGeneral Description and
Operation, ECT Sensor
F54Vapor Pressure (Fuel Tank
Pressure) Sensor GroundGRN0.0V0.0VGeneral Description and
Operation, VP Sensor
F55Not UsedÐÐÐÐ
F56Injector Cylinder #5GRN/BLKB+B+General Description and
Operation, Fuel Injector
F57Ignition FeedRED/WHTB+B+Chassis Electrical
F58Class 2 DataORN/BLK0.0V0.0VGeneral Description
F59Not UsedÐÐÐÐ
F60Not UsedÐÐÐÐ

6E±25
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
PCM Pinout Table, 80-Way Red Connector ± Row ªS61 ~ 80º
060RY00051
PINPIN FunctionWire ColorIGN ONENG RUNRefer To
S61Intake Air Temperature
(IAT) Sensor GroundYEL/GRN0.0V0.0VGeneral Description and
Operation, IAT
S62ION Sensing ModuleRED1.555V1.555VGeneral Description and
Operation, ION Sensing
Module
S63Bank 1 HO2S 2 HighWHT0.3V0.1±0.9VGeneral Description and
Operation, Catalyst Monitor
HO2S
S64Bank 2 HO2S 1 HighPNK0.3V0.1±0.9VGeneral Description and
Operation, Catalyst Monitor
HO2S
S65Bank 2 HO2S 2 HighGRN0.3V0.1±0.9VGeneral Description and
Operation, Catalyst Monitor
HO2S
S66Transmission Fluid
Temperature SensorRED/BLK0.5±4.9V
(depends on
temperature)0.5±4.9V
(depends on
temperature)4L30E T/Mission
S67Exhaust Gas Recirculation
(EGR) Position SignalGRY/RED0.6V0.6VGeneral Description and
Operation, EGR Control
S68Accelerator Position (AP)
Sensor 1WHT0.41±0.45V0.41±0.45VOn-Vehicle Service
S69Throttle Valve DC
Motor(+: FWD)GRNDuty CycleDuty CycleGeneral Description and
Operation, ETC
S70Not UsedÐÐÐÐ
S71Not UsedÐÐÐÐ
S72Ignition FeedRED/GRNB+B+Chassis Electrical
S73Auto Cruise Main LampGRN/WHTB+B+Chassis Electrical
S74Variable Intake ManifoldYEL/BLK0.0VB+ (rpm
3600 over)General Description
S75Canister Purge Cut
Solenoid ValveRED/WHT6.0V Tank
empty5.7V Tank
emptyGeneral Description and
Operation, EVAP
S76Throttle Position (TP) 1
Sensor SignalBLU0.5±0.8V0.5±0.8V (at
idle)General Description and
Operation, TPS

6E±34
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
dissatisfaction. The following list of non-vehicle faults
does not include every possible fault and may not apply
equally to all product lines.
Fuel Quality
Fuel quality is not a new issue for the automotive industry,
but its potential for turning on the MIL (ªCheck Engineº
lamp) with OBD II systems is new.
Fuel additives such as ªdry gasº and ªoctane enhancersº
may affect the performance of the fuel. If this results in an
incomplete combustion or a partial burn, it will show up as
a Misfire DTC P0300. The Reed Vapor Pressure of the
fuel can also create problems in the fuel system,
especially during the spring and fall months when severe
ambient temperature swings occur. A high Reed Vapor
Pressure could show up as a Fuel Trim DTC due to
excessive canister loading. High vapor pressures
generated in the fuel tank can also affect the Evaporative
Emission diagnostic as well.
Using fuel with the wrong octane rating for the vehicle
may cause driveability problems. Many of the major fuel
companies advertise that using ªpremiumº gasoline will
improve the performance of the vehicle. Most premium
fuels use alcohol to increase the octane rating of the fuel.
Although alcohol-enhanced fuels may raise the octane
rating, the fuel's ability to turn into vapor in cold
temperatures deteriorates. This may affect the starting
ability and cold driveability of the engine.
Low fuel levels can lead to fuel starvation, lean engine
operation, and eventually engine misfire.
Non-OEM Parts
All of the OBD II diagnostics have been calibrated to run
with OEM parts. Something as simple as a
high-performance exhaust system that affects exhaust
system back pressure could potentially interfere with the
operation of the EGR valve and thereby turn on the MIL
(ªCheck Engineº lamp). Small leaks in the exhaust
system near the post catalyst oxygen sensor can also
cause the MIL (ªCheck Engineº lamp) to turn on.
Aftermarket electronics, such as transceivers, stereos,
and anti-theft devices, may radiate EMI into the control
system if they are improperly installed. This may cause a
false sensor reading and turn on the MIL (ªCheck Engineº
lamp).
Environment
Temporary environmental conditions, such as localized
flooding, will have an effect on the vehicle ignition system.
If the ignition system is rain-soaked, it can temporarily
cause engine misfire and turn on the MIL (ªCheck Engineº
lamp).
Refueling
A new OBD II diagnostic was introduced in 1996 on some
vehicles. This diagnostic checks the integrity of the entire
evaporative emission system. If the vehicle is restarted
after refueling and the fuel cap is not secured correctly,
the on-board diagnostic system will sense this as a
system fault and turn on the MIL (ªCheck Engineº lamp)
with a DTC P0440.Vehicle Marshaling
The transportation of new vehicles from the assembly
plant to the dealership can involve as many as 60 key
cycles within 2 to 3 miles of driving. This type of operation
contributes to the fuel fouling of the spark plugs and will
turn on the MIL (ªCheck Engineº lamp) with a P0300
Misfire DTC.
Poor Vehicle Maintenance
The sensitivity of OBD II diagnostics will cause the MIL
(ªCheck Engineº lamp) to turn on if the vehicle is not
maintained properly. Restricted air filters, fuel filters, and
crankcase deposits due to lack of oil changes or improper
oil viscosity can trigger actual vehicle faults that were not
previously monitored prior to OBD II. Poor vehicle
maintenance can't be classified as a ªnon-vehicle faultº,
but with the sensitivity of OBD II diagnostics, vehicle
maintenance schedules must be more closely followed.
Related System Faults
Many of the OBD II system diagnostics will not run if the
PCM detects a fault on a related system or component.
One example would be that if the PCM detected a Misfire
fault, the diagnostics on the catalytic converter would be
suspended until Misfire fault was repaired. If the Misfire
fault was severe enough, the catalytic converter could be
damaged due to overheating and would never set a
Catalyst DTC until the Misfire fault was repaired and the
Catalyst diagnostic was allowed to run to completion. If
this happens, the customer may have to make two trips to
the dealership in order to repair the vehicle.
Emissions Control Information Label
The engine compartment ªVehicle Emissions Control
Information Labelº contains important emission
specifications and setting procedures. In the upper left
corner is exhaust emission information. This identifies
the emission standard (Federal, California, or Canada) of
the engine, the displacement of the engine in liters, the
class of the vehicle, and the type of fuel metering system.
There is also an illustrated emission components and
vacuum hose schematic.
This label is located in the engine compartment of every
vehicle. If the label has been removed it should be
replaced. It can be ordered from Isuzu Dealership.
Visual / Physical Engine Compartment
Inspection
Perform a careful visual and physical engine
compartment inspection when performing any diagnostic
procedure or diagnosing the cause of an emission test
failure. This can often lead to repairing a problem without
further steps. Use the following guidelines when
performing a visual/physical inspection:

Inspect all vacuum hoses for pinches, cuts,
disconnections, and proper routing.

Inspect hoses that are difficult to see behind other
components.

6E±35
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS

Inspect all wires in the engine compartment for proper
connections, burned or chafed spots, pinched wires,
contact with sharp edges or contact with hot exhaust
manifolds or pipes.
Basic Knowledge of Tools Required
NOTE: Lack of basic knowledge of this powertrain when
performing diagnostic procedures could result in an
incorrect diagnosis or damage to powertrain
components. Do not attempt to diagnose a powertrain
problem without this basic knowledge.
A basic understanding of hand tools is necessary to effec-
tively use this section of the Service Manual.
Serial Data Communications
Class 2 Serial Data Communications
Government regulations require that all vehicle
manufacturers establish a common communication
system. This vehicle utilizes the ªClass 2º communication
system. Each bit of information can have one of two
lengths: long or short. This allows vehicle wiring to be
reduced by transmitting and receiving multiple signals
over a single wire. The messages carried on Class 2 data
streams are also prioritized. If two messages attempt to
establish communications on the data line at the same
time, only the message with higher priority will continue.
The device with the lower priority message must wait.
The most significant result of this regulation is that it
provides Scan tool manufacturers with the capability to
access data from any make or model vehicle that is sold.
The data displayed on other Scan tools will appear the
same, with some exceptions. Some Scan tools will only
be able to display certain vehicle parameters as values
that are a coded representation of the true or actual value.
On this vehicle the Scan tool displays the actual values for
vehicle parameters. It will not be necessary to perform
any conversions from coded values to actual values.
On-Board Diagnostic (OBD II)
On-Board Diagnostic Tests
A diagnostic test is a series of steps, the result of which is
a pass or fail reported to the diagnostic executive. When
a diagnostic test reports a pass result, the diagnostic
executive records the following data:

The diagnostic test has been completed since the last
ignition cycle.

The diagnostic test has passed during the current
ignition cycle.

The fault identified by the diagnostic test is not
currently active.
When a diagnostic test reports a fail result, the diagnostic
executive records the following data:

The diagnostic test has been completed since the last
ignition cycle.

The fault identified by the diagnostic test is currently
active.

The fault has been active during this ignition cycle.

The operating conditions at the time of the failure.Remember, a fuel trim DTC may be triggered by a list of
vehicle faults. Make use of all information available (other
DTCs stored, rich or lean condition, etc.) when
diagnosing a fuel trim fault.
Comprehensive Component Monitor
Diagnostic Operation
Comprehensive component monitoring diagnostics are
required to monitor emissions-related input and output
powertrain components. The
CARB OBD II
Comprehensive Component Monitoring List Of
Components Intended To illuminate MIL
is a list of
components, features or functions that could fall under
this requirement.
Input Components:
Input components are monitored for circuit continuity and
out-of-range values. This includes rationality checking.
Rationality checking refers to indicating a fault when the
signal from a sensor does not seem reasonable, i.e.
Throttle Position (TP) sensor that indicates high throttle
position at low engine loads or MAP voltage. Input
components may include, but are not limited to the
following sensors:

Vehicle Speed Sensor (VSS)

Crankshaft Position (CKP) sensor

Throttle Position (TP) sensor

Engine Coolant Temperature (ECT) sensor

Manifold Absolute Pressure (MAP) sensor

Mass Air Flow (MAF) sensor
In addition to the circuit continuity and rationality check,
the ECT sensor is monitored for its ability to achieve a
steady state temperature to enable closed loop fuel
control.
Output Components:
Output components are diagnosed for proper response to
control module commands. Components where
functional monitoring is not feasible will be monitored for
circuit continuity and out-of-range values if applicable.
Output components to be monitored include, but are not
limited to, the following circuits:

Control module controlled EVAP Canister Purge
Valve

Electronic Transmission controls

A/C relays

VSS output

MIL control

Cruise control inhibit
Refer to PCM and Sensors in General Descriptions.
Passive and Active Diagnostic Tests
A passive test is a diagnostic test which simply monitors a
vehicle system or component. Conversely, an active test,
actually takes some sort of action when performing
diagnostic functions, often in response to a failed passive
test. For example, the EGR diagnostic active test will
force the EGR valve open during closed throttle decel
and/or force the EGR valve closed during a steady state.
Either action should result in a change in manifold
pressure.

6E±36
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Intrusive Diagnostic Tests
This is any on-board test run by the Diagnostic
Management System which may have an effect on
vehicle performance or emission levels.
Warm-Up Cycle
A warm-up cycle means that engine at temperature must
reach a minimum of 70
C (160
F)
and rise at least 22
C
(40
F) over the course of a trip.
Freeze Frame
Freeze Frame is an element of the Diagnostic
Management System which stores various vehicle
information at the moment an emissions-related fault is
stored in memory and when the MIL is commanded on.
These data can help to identify the cause of a fault. Refer
to
Storing And Erasing Freeze Frame Data in this section
for more detailed information.
Failure Records
Failure Records data is an enhancement of the OBD II
Freeze Frame feature. Failure Records store the same
vehicle information as does Freeze Frame, but it will store
that information for any fault which is stored in on-board
memory, while Freeze Frame stores information only for
emission-related faults that command the MIL on.
System Status and Drive Cycle for
Satisfying Federal Inspection/Maintenance
(I/M 240) Regulations
I/M Ready Status means a signal or flag for each
emission system test that had been set in the PCM. I/M
Ready Status indicates that the vehicle on-board
emissions diagnostics have been run. I/M Ready Status
is not concerned whether the emission system passed or
failed the test, only that on-board diagnosis is complete.
Not all vehicles use all possible I/M flags.
Common OBD II Terms
Diagnostic
When used as a noun, the word diagnostic refers to any
on-board test run by the vehicle's Diagnostic
Management System. A diagnostic is simply a test run on
a system or component to determine if the system or
component is operating according to specification. There
are many diagnostics, shown in the following list:

Misfire

Oxygen sensors

Oxygen sensor heaters

EGR

Catalyst monitoring
Enable Criteria
The term ªenable criteriaº is engineering language for the
conditions necessary for a given diagnostic test to run.
Each diagnostic has a specific list of conditions which
must be met before the diagnostic will run. ªEnable
criteriaº is another way of saying ªconditions requiredº.The enable criteria for each diagnostic is listed on the first
page of the DTC description in Section 6E under the
heading ªConditions for Setting the DTCº. Enable criteria
varies with each diagnostic, and typically includes, but is
not limited to the following items:

engine speed

vehicle speed

ECT

MAF/MAP

barometric pressure

IAT

TP

high canister purge

fuel trim

TCC enabled

A/C on
Trip
Technically, a trip is a key on-run-key off cycle in which all
the enable criteria for a given diagnostic are met, allowing
the diagnostic to run. Unfortunately, this concept is not
quite that simple. A trip is official when all the enable
criteria for a given diagnostic are met. But because the
enable criteria vary from one diagnostic to another, the
definition of trip varies as well. Some diagnostics are run
when the vehicle is at operating temperature, some when
the vehicle first starts up; some require that the vehicle be
cruising at a steady highway speed, some run only when
the vehicle is idle; some diagnostics function with the
TCC disabled. Some run only immediately following a
cold engine start-up.
A trip then, is defined as a key on-run-key off cycle in
which the vehicle was operated in such a way as to satisfy
the enabling criteria for a given diagnostic, and this
diagnostic will consider this cycle to be one trip. However,
another diagnostic with a different set of enable criteria
(which were not met) during this driving event, would not
consider it a trip. No trip will occur for that particular
diagnostic until the vehicle is driven in such a way as to
meet all the enable criteria.
The Diagnostic Executive
The Diagnostic Executive is a unique segment of
software which is designed to coordinate and prioritize
the diagnostic procedures as well as define the protocol
for recording and displaying their results. The main
responsibilities of the Diagnostic Executive are listed as
the following:

Commanding the MIL (ªCheck Engineº lamp) on and
off

DTC logging and clearing

Freeze Frame data for the first emission related DTC
recorded

Non-emission related Service Lamp

Operating conditions Failure Records buffer, (the
number of records will vary)

Current status information on each diagnostic

System Status (I/M ready)

6E±37
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
The Diagnostic Executive records DTCs and turns on the
MIL when emission-related faults occur. It can also turn
off the MIL if the conditions cease which caused the DTC
to set.
Diagnostic Information
The diagnostic charts and functional checks are designed
to locate a faulty circuit or component through a process
of logical decisions. The charts are prepared with the
requirement that the vehicle functioned correctly at the
time of assembly and that there are no multiple faults
present.
There is a continuous self-diagnosis on certain control
functions. This diagnostic capability is complemented by
the diagnostic procedures contained in this manual. The
language of communicating the source of the malfunction
is a system of diagnostic trouble codes. When a
malfunction is detected by the control module, a
diagnostic trouble code is set and the Malfunction
Indicator Lamp (MIL) (ªCheck Engineº lamp) is
illuminated.
Malfunction Indicator Lamp (MIL)
The Malfunction Indicator Lamp (MIL) looks the same as
the MIL you are already familiar with (ªCheck Engineº
lamp). However, OBD II requires that it illuminate under a
strict set of guide lines.
Basically, the MIL is turned on when the PCM detects a
DTC that will impact vehicle emissions.
The MIL is under the control of the Diagnostic Executive.
The MIL will be turned on if an emissions-related
diagnostic test indicates a malfunction has occurred. It
will stay on until the system or component passes the
same test, for three consecutive trips, with no emissions
related faults.
If the vehicle is experiencing a misfire malfunction which
may cause damage to the Three-Way Catalytic
Converter (TWC), the MIL will flash once per second.
This will continue until the vehicle is outside of speed and
load conditions which could cause possible catalyst
damage, and the MIL will stop flashing and remain on
steady.
Extinguishing the MIL
When the MIL is on, the Diagnostic Executive will turn off
the MIL after
three(3) consecutive trips that a ªtest
passedº has been reported for the diagnostic test that
originally caused the MIL to illuminate.
Although the MIL has been turned off, the DTC will remain
in the PCM memory (both Freeze Frame and Failure
Records) until
forty(40) warm-up cycles after no faults
have been completed.
If the MIL was set by either a fuel trim or misfire-related
DTC, additional requirements must be met. In addition to
the requirements stated in the previous paragraph, these
requirements are as follows:

The diagnostic tests that are passed must occur
within 375 RPM of the RPM data stored at the time the
last test failed.

Plus or minus ten (10) percent of the engine load that
was stored at the time the last failed.
Similar engine temperature conditions (warmed up or
warming up ) as those stored at the time the last test
failed.
Meeting these requirements ensures that the fault which
turned on the MIL has been corrected.
The MIL (ªCheck Engineº lamp) is on the instrument
panel and has the following function:

It informs the driver that a fault affects vehicle
emission levels has occurred and that the vehicle
should be taken for service as soon as possible.

As a bulb and system check, the MIL will come ªONº
with the key ªONº and the engine not running. When
the engine is started, the MIL will turn ªOFF.º

When the MIL remains ªONº while the engine is
running, or when a malfunction is suspected due to a
driveability or emissions problem, a Powertrain
On-Board Diagnostic (OBD ll) System Check must be
performed. The procedures for these checks are
given in On-Board Diagnostic (OBD) System Check.
These checks will expose faults which may not be
detected if other diagnostics are performed first.
DTC Types
Each DTC is directly related to a diagnostic test. The
Diagnostic Management System sets DTC based on the
failure of the tests during a trip or trips. Certain tests must
fail two (2) consecutive trips before the DTC is set. The
following are the four (4) types of DTCs and the
characteristics of those codes:

Type A

Emissions related

Requests illumination of the MIL of the first trip with a
fail

Stores a History DTC on the first trip with a fail

Stores a Freeze Frame (if empty)

Stores a Fail Record

Updates the Fail Record each time the diagnostic
test fails

Type B

Emissions related

ªArmedº after one (1) trip with a fail

ªDisarmedº after one (1) trip with a pass

Requests illumination of the MIL on the
second
consecutive trip
with a fail

Stores a History DTC on the second consecutive trip
with a fail (The DTC will be armed after the first fail)

Stores a Freeze Frame on the second consecutive
trip with a fail (if empty)

Stores a Fail Record when the first test fails (not
dependent on
consecutive trip fails)

Updates the Fail Record each time the diagnostic
test fails
(Some special conditions apply to misfire and fuel trim
DTCs)

Type C (if the vehicle is so equipped)

Non-Emissions related

Requests illumination of the Service

Stores a History DTC on the
first trip with a fail

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6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS

Does not store a Freeze Frame

Stores Fail Record when test fails

Updates the Fail Record each time the diagnostic
test fails

Type D

Non-Emissions related

Not request illumination of any lamp

Stores a History DTC on the
first trip with a fail


Does not store a Freeze Frame

Stores Fail Record when test fails

Updates the Fail Record each time the diagnostic
test fails
IMPORTANT:Only four Fail Records can be stored.
Each Fail Record is for a different DTC. It is possible that
there will not be Fail Records for every DTC if multiple
DTCs are set.
Special Cases of Type B Diagnostic Tests
Unique to the misfire diagnostic, the Diagnostic Executive
has the capability of alerting the vehicle operator to
potentially damaging levels of misfire. If a misfire
condition exists that could potentially damage the
catalytic converter as a result of high misfire levels, the
Diagnostic Executive will command the MIL to ªflashº at a
rate of once per second during those the time that the
catalyst damaging misfire condition is present.
Fuel trim and misfire are special cases of
Type B
diagnostics. Each time a fuel trim or misfire malfunction is
detected, engine load, engine speed, and engine coolant
temperature are recorded.
When the ignition is turned off, the last reported set of
conditions remain stored. During subsequent ignition
cycles, the stored conditions are used as reference for
similar conditions. If a malfunction occurs during two
consecutive trips, the Diagnostic Executive treats the
failure as a normal
Type B diagnostic, and does not use
the stored conditions. However, if a malfunction occurs
on two non-consecutive trips, the stored conditions are
compared with the current conditions. The MIL will then
illuminate under the following conditions:

When the engine load conditions are within 10% of
the previous test that failed.

Engine speed is within 375 rpm, of the previous test
that failed.

Engine coolant temperature is in the same range as
the previous test that failed.Storing and Erasing Freeze Frame Data and Failure
Records
Government regulations require that engine operating
conditions be captured whenever the MIL is illuminated.
The data captured is called Freeze Frame data. The
Freeze Frame data is very similar to a single record of
operating conditions. Whenever the MIL is illuminated,
the corresponding record of operating conditions is
recorded to the Freeze Frame buffer.
Freeze Frame data can only be overwritten with data
associated with a misfire or fuel trim malfunction. Data
from these faults take precedence over data associated
with any other fault. The Freeze Frame data will not be
erased unless the associated history DTC is cleared.
Each time a diagnostic test reports a failure, the current
engine operating conditions are recorded in the
Failure
Records
buffer. A subsequent failure will update the
recorded operating conditions. The following operating
conditions for the diagnostic test which failed
typically
include the following parameters:

Air Fuel Ratio

Air Flow Rate

Fuel Trim

Engine Speed

Engine Load

Engine Coolant Temperature

Vehicle Speed

TP Angle

AP Angle

MAP/BARO

Injector Base Pulse Width

Loop Status
Intermittent Malfunction Indicator Lamp
In the case of an ªintermittentº fault, the MIL (ªCheck
Engineº lamp) may illuminate and then (after three trips)
go ªOFFº. However, the corresponding diagnostic trouble
code will be stored in memory. When unexpected
diagnostic trouble codes appear, check for an intermittent
malfunction.
A diagnostic trouble code may reset. Consult the
ªDiagnostic Aidsº associated with the diagnostic trouble
code. A physical inspection of the applicable sub-system
most often will resolve the problem.
Data Link Connector (DLC)
The provision for communication with the control module
is the Data Link Connector (DLC). It is located at the
lower left of the instrument panel behind a small square
cover. The DLC is used to connect to the Tech 2 Scan
Tool. Some common uses of the Tech 2 are listed below:

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6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS

Identifying stored Diagnostic Trouble Codes (DTCs).

Clearing DTCs.

Performing output control tests.

Reading serial data.
TS24064
Decimal/Binary/Hexadecimal Conversions
Beginning in 1996, Federal Regulations require that all
auto manufacturers selling vehicles in the United States
provide Scan Tool manufacturers with software
information to display vehicle operating parameters. All
Scan Tool manufacturers will display a variety of vehicle
information which will aid in repairing the vehicle. Some
Scan Tools will display encoded messages which will aid
in determining the nature of the concern. The method of
encoding involves the use of a two additional numbering
systems: Binary and Hexadecimal.
The binary number system has a base of two numbers.
Each digit is either a 0 or a 1. A binary number is an eight
digit number and is read from right to left. Each digit has a
position number with the farthest right being the 0 position
and the farthest left being the 7 position. The 0 position,
when displayed by a 1, indicates 1 in decimal. Each
position to the left is double the previous position and
added to any other position values marked as a 1.
A hexadecimal system is composed of 16 different alpha
numeric characters. The alpha numeric characters used
are numbers 0 through 9 and letters A through F. The
hexadecimal system is the most natural and common
approach for Scan Tool manufacturers to display data
represented by binary numbers and digital code.
Verifying Vehicle Repair
Verification of vehicle repair will be more comprehensive
for vehicles with OBD II system diagnostic. Following a
repair, the technician should perform the following steps:
1. Review and record the Fail Records and/or Freeze
Frame data for the DTC which has been diagnosed
(Freeze Frame data will only be stored for an A or B
type diagnostic and only if the MIL has been
requested).
2. Clear DTC(s).
3. Operate the vehicle within conditions noted in the Fail
Records and/or Freeze Frame data.
4. Monitor the DTC status information for the DTC which
has been diagnosed until the diagnostic test
associated with that DTC runs.
Following these steps are very important in verifying
repairs on OBD ll systems. Failure to follow these steps
could result in unnecessary repairs.
Reading Diagnostic Trouble Codes Using
The Tech 2 Scan Tool
The procedure for reading diagnostic trouble code(s) is to
use a diagnostic Scan Tool. When reading DTC(s), follow
instructions supplied by tool manufacturer.
Clearing Diagnostic Trouble Codes
IMPORTANT:Do not clear DTCs unless directed to do
so by the service information provided for each diagnostic
procedure. When DTCs are cleared, the Freeze Frame
and Failure Record data which may help diagnose an
intermittent fault will also be erased from memory.
If the fault that caused the DTC to be stored into memory
has been corrected, the Diagnostic Executive will begin to
count the ªwarm-upº cycles with no further faults
detected, the DTC will automatically be cleared from the
PCM memory.
To clear Diagnostic Trouble Codes (DTCs), use the
diagnostic Scan Tool ªclear DTCsº or ªclear informationº
function. When clearing DTCs follow instructions
supplied by the tool manufacturer.
When a Scan Tool is not available, DTCs can also be
cleared by disconnecting
one of the following sources for
at least thirty (30) seconds.
NOTE: To prevent system damage, the ignition key must
be ªOFFº when disconnecting or reconnecting battery
power.

The power source to the control module. Examples:
fuse, pigtail at battery PCM connectors, etc.

The negative battery cable. (Disconnecting the
negative battery cable will result in the loss of other
on-board memory data, such as preset radio tuning).

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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.