Opel Frontera UE. Manual - part 786

6E1–27

X22SE 2.2L ENGINE DRIVEABILITY AND EMISSION

DIAGNOSIS Strategy–Based

Diagnostics

Strategy–Based Diagnostics

The strategy–based diagnostic is a uniform approach to
repair all Electrical/Electronic (E/E) systems. The
diagnostic flow can always be used to resolve an E/E
system problem and is a starting point when repairs are
necessary. The following steps will instruct the technician
how to proceed with a diagnosis:

1. Verify the customer complaint.

To verify the customer complaint, the technician
should know the normal operation of the system.

2. Perform preliminary checks.

Conduct a thorough visual inspection.

Review the service history.

Detect unusual sounds or odors.

Gather diagnostic trouble code information to
achieve an effective repair.

3. Check bulletins and other service information.

This includes videos, newsletters, etc.

4. Refer to service information (manual) system

check(s).

”System checks” contain information on a system
that may not be supported by one or more DTCs.
System checks verify proper operation of the
system. This will lead the technician in an organized
approach to diagnostics.

5. Refer to service diagnostics.

DTC Stored

Follow the designated DTC chart exactly to make an
effective repair.

No DTC

Select the symptom from the symptom tables. Follow the
diagnostic paths or suggestions to complete the repair.
You may refer to the applicable component/system check
in the system checks.

No Matching Symptom

1. Analyze the complaint.
2. Develop a plan for diagnostics.
3. Utilize the wiring diagrams and the theory of

operation.

Combine technician knowledge with efficient use of the
available service information.

Intermittents

Conditions that are not always present are called
intermittents. To resolve intermittents, perform the
following steps:

1. Observe history DTCs, DTC modes, and

freeze–frame data.

2. Evaluate the symptoms and the conditions described

by the customer.

3. Use a check sheet or other method to identify the

circuit or electrical system component.

4. Follow the suggestions for intermittent diagnosis

found in the service documentation.

Most Scan Tools, such as the Tech 2, have
data–capturing capabilities that can assist in detecting
intermittents.

No Trouble Found

This condition exists when the vehicle is found to operate
normally. The condition described by the customer may
be normal. Verify the customer complaint against another
vehicle that is operating normally. The condition may be
intermittent. Verify the complaint under the conditions
described by the customer before releasing the vehicle.

1. Re–examine the complaint.

When the complaint cannot be successfully found or
isolated, a re–evaluation is necessary. The complaint
should be re–verified and could be intermittent as
defined in

Intermittents, or could be normal.

2. Repair and verify.

After isolating the cause, the repairs should be made.
Validate for proper operation and verify that the
symptom has been corrected. This may involve road
testing or other methods to verify that the complaint
has been resolved under the following conditions:

Conditions noted by the customer.

If a DTC was diagnosed, verify a repair by
duplicating conditions present when the DTC was
set as noted in the Failure Records or Freeze
Frame data.

Verifying Vehicle Repair

Verification of the vehicle repair will be more
comprehensive for vehicles with OBD II system
diagnostics. Following a repair, the technician should
perform the following steps:

IMPORTANT:

Follow the steps below when you verify

repairs on OBD II systems. Failure to follow these steps
could result in unnecessary repairs.

1. Review and record the Failure Records and the

Freeze Frame data for the DTC which has been
diagnosed (Freeze Fame data will only be stored for
an A or B type diagnostic and only if the MIL (”Check
Engine” lamp) has been requested).

2. Clear the DTC(s).
3. Operate the vehicle within conditions noted in the

Failure Records and 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.

GENERAL SERVICE INFORMATION

Non–OEM Parts

All of the OBD 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

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X22SE 2.2L ENGINE DRIVEABILITY AND EMISSION

operation of the EGR valve and thereby turn on the MIL
(”Check Engine” lamp). Small leaks in the exhaust
system near the post catalyst oxygen sensor can also
cause the MIL (”Check Engine” lamp) to turn on.
Aftermarket electronics, such as transceiver, 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 (”Check Engine”
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 (”Check Engine”
lamp).

Emissions Control Information Label

The engine compartment ”Vehicle Emissions Control
Information Label” contains important emission
specifications and setting procedures. In the upper left
corner is exhaust emission information. 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 Dealer ship.

Maintenance Schedule

Refer to the Maintenance Schedule.

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,
disconnection, and Droper routing.

Inspect hoses that are difficult to see behind other
components.

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
effectively use this section of the Service Manual.

SERIAL DATA COMMUNICATIONS

Class II Serial Data Communications

Government regulations require that all vehicle
manufacturers establish a common communication
system. This vehicle utilizes the ”Class II” 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 II 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
Tech 2 manufacturers with the capability to access data
from any make or model vehicle that is sold.
The data displayed on the other Tech 2 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.
For more information on this system of coding, refer to
Decimal/Binary/Hexadecimal Conversions. On this
vehicle the Tech 2 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)

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

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X22SE 2.2L ENGINE DRIVEABILITY AND EMISSION

DTCs stored, rich or lean condition, etc.) when
diagnosing a fuel trim fault.

Comprehensive Component Monitor
Diagnostic Operation

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

Camshaft Position (CMP) sensor

Manifold Absolute Pressure (MAP) 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 circuit:

Idle Air Control (IAC) Motor

EVAP Canister Purge Valve Solenoid

A/C relays

Cooling fan relay(s)

VSS output

MIL control

Refer to ECM 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.

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

(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 Fame Data for more
detailed information.

Failure Records
Failure Records data is an enhancement of the OBD
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.

Common OBD 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:

Oxygen sensors

Oxygen sensor heaters

EGR

Enable Criteria
The term ”enable criteria” 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. ”Enable
criteria” is another way of saying ”conditions required”.
The enable criteria for each diagnostic is listed on the first
page of the DTC description in Section 6E under the
heading ”Conditions for Setting the DTC”. Enable criteria
varies with each diagnostic, and typically includes, but is
not limited to the following items:

engine speed

vehicle speed

ECT

MAP

barometric pressure

IAT

A/C ON

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X22SE 2.2L ENGINE DRIVEABILITY AND EMISSION

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 at 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
follows:

Commanding the MIL (”Check Engine” lamp) ON and
OFF

DTC logging and clearing

Freeze Frame data for the first emission related DTC
recorded

Non–emission related Service Lamp (future)

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

Current status information on each diagnostic

System Status (I/M ready)

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 complimented 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) (”Check Engine” lamp) is
illuminated.

Malfunction Indicator Lamp (MIL)
The Malfunction Indicator Lamp (MIL) looks the same as
the MIL you are already familiar with (”Check Engine”
lamp). However, OBD requires that it illuminate under a
strict set of guide lines.
Basically, the MIL is turned ON when the ECM detects a
DTC that will impact the 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.

Extinguishing the MIL
When the MIL is ON, the Diagnostic Executive will turn
OFF the MIL after

three (3) consecutive trips that a ”test

passed” 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 ECM 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 with
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 test 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 (”Check Engine” lamp) is on the instrument panel
and has the following functions:

It informs the driver that a fault that 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 ON
with the key ON and the engine not running. When the
engine is started, the MIL will turn OFF.

When the MIL remains ON while the engine is
running, or when a malfunction is suspected due to a
driveability or emissions problem, a Powertrain
On–Board Diagnostic (OBD) 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.

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