ECU OPEL FRONTERA 1998 Workshop Manual

6C–10
ENGINE FUEL
Reuse of Quick–Connector
(Delivery Pipe)
Replace the pipe and connector if scratch, dent or
crack is found.
Remove mud and dust from the pipe and make sure
that the end including spool is free of defects, such as
scratch, rust, and dent, which may cause poor
sealability. If defective, replace with a new pipe.
If the retainer removed according to the removal step
above is attached to the pipe, clean and insert it
straight into the quick-connector till it clicks. After it
clicks, try pulling it out to make sure that it is not drawn
and is securely locked.
NOTE: The retainer, once removed from the pipe, cannot
be reused. Just replace with a new retainer. Insert the
new retainer into the connector side until it clicks, and
connect the pipe as inserting it into the retainer until it
clicks.
141RW018
(Return Pipe)
Replace the pipe and connector if scratch, dent or
crack is found.
Remove mud or dust from the pipe and make sure
that the end including spool is free from defects, such
as scratch, rust, and dent, which may cause poor
sealability. If defective, replace with a new pipe.
After cleaning the pipe, insert it straight into the
connector until it clicks. After it clicks, try pulling it out
to make sure that it is not drawn and is securely
locked.
141RW017
Assembling Advice
Application of engine oil or light oil to the pipe facilitates
connecting work. The work should be started immediately
after lubrication, since dust may stick to the pipe surface
to cause poor sealability if a long time passes after
lubrication.
Test/Inspection After Assembling
1. Reconnect the battery negative cable.
2. Turn the ignition key to the “ON” position and check
pump startup sound. As the pump is actuated to raise
fuel pressure, check and see fuel leak from the piping
system.
3. Make sure of no fuel leakage by conducting the above
fuel leak check a few times.
4. Start the engine and make sure of stable idling speed
and normal vehicle run.The entry of dust during the
work may sometimes affect the fuel injection system.

6D3–22STARTING AND CHARGING SYSTEM
6. Secure the pulley directly in the vise between two
copper plates, and remove the nut and pulley.
066RS010
7. Remove four nuts(8) that secure the front cover
assembly and rear end cover, and an insulator(9).
066RW005
8. Use the puller to remove the rear end cover.
9. Rotor assembly
066RS012
10. Pull the rotor assembly(10) off the front cover
assembly(12) using a bench press(11).
066RW006

6D3–25 STARTING AND CHARGING SYSTEM
1. Using a press with a socket wrench attached,
reassemble rotor and rear end cover assembly in the
front cover.
066RS022
2. Install pulley on the rotor.
Secure the pulley directly in the vise between two
copper plates, and tighten nut to the specified torque.
Torque: 111 Nꞏm (11.3 Kgꞏm/82 lb ft)
066RS010
Bench Test
Conduct a bench test of the generator.
066RS023
Preparation
Remove generator from the vehicle (see “Generator
removal”).
1. Secure generator to the bench test equipment and
connect wires.
Terminal “IG” for energization
Terminal “L” for neutral (warning lamp)
Terminal “B” for output
2. Conduct the generator characteristic test.
Characteristics of generator are shown in illustration.
Repair or replace the generator if its outputs are
abnormal.
B06RW001

6E–1 ENGINE DRIVEABILITY AND EMISSIONS
ENGINE
ENGINE DRIVEABILITY AND EMISSIONS
CONTENTS
Specifications 6E–5. . . . . . . . . . . . . . . . . . . . . . . . .
Tightening Specifications 6E–5. . . . . . . . . . . . . . .
Vehicle Type Specifications 6E–5. . . . . . . . . . . . .
Diagrams and Schematics 6E–6. . . . . . . . . . . . . . . .
PCM Wiring Diagram (1 of 11) 6E–6. . . . . . . . . . .
PCM Wiring Diagram (2 of 11) For EC,
THAILAND, SOUTH EAST ASIA, LATIN
AMERICA, GULF, SAUDI, CHINA. 6E–7. . . . . .
PCM Wiring Diagram (3 of 11) For SOUTH
AFRICA and EXP. 6E–8. . . . . . . . . . . . . . . . . . . . .
PCM Wiring Diagram (4 of 11) 6E–9. . . . . . . . . . .
PCM Wiring Diagram (5 of 11) 6E–10. . . . . . . . . . .
PCM Wiring Diagram (6 of 11) For
AUSTRALIA, THAILAND, SOUTH EAST
ASIA, LATIN AMERICA, GULF, SAUDI,
LATIN AMERICA. 6E–11. . . . . . . . . . . . . . . . . . . . .
PCM Wiring Diagram (7 of 11) For EC. 6E–12. . .
PCM Wiring Diagram (8 of 11) For EXPORT
and SOUTH AFRICA. 6E–13. . . . . . . . . . . . . . . . .
PCM Wiring Diagram (9 of 11) Except EXP
and SOUTH AFRICA 6E–14. . . . . . . . . . . . . . . . . .
PCM Wiring Diagram (10 of 11) For
EXPORT and SOUTH AFRICA 6E–15. . . . . . . . .
PCM Wiring Diagram (11 of 11) 6E–16. . . . . . . . . .
PCM Pinouts 6E–17. . . . . . . . . . . . . . . . . . . . . . . . . . .
PCM Pinout Table, 32-Way Red
Connector – Row “A” 6E–17. . . . . . . . . . . . . . . . . .
PCM Pinout Table, 32-Way Red
Connector – Row “B” 6E–19. . . . . . . . . . . . . . . . . .
PCM Pinout Table, 32-Way White
Connector – Row “C” (For EC) 6E–20. . . . . . . . . .
PCM Pinout Table, 32-Way White
Connector – Row “C” (For except EC) 6E–21. . .
PCM Pinout Table, 32-Way White
Connector – Row “D”
(For except EXPORT and SOUTH
AFRICA) 6E–22. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
PCM Pinout Table, 32-Way White
Connector – Row “D”
(For EXPORT and SOUTH AFRICA) 6E–23. . . . .
PCM Pinout Table, 32-Way Blue
Connector – Row “E”
(For except EXPORT and SOUTH
AFRICA) 6E–24. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
PCM Pinout Table, 32-Way Blue
Connector – Row “E”
(For EXPORT and SOUTH AFRICA) 6E–26. . . . .
PCM Pinout Table, 32-Way Blue
Connector – Row “F” 6E–27. . . . . . . . . . . . . . . . . .
Component Locators 6E–28. . . . . . . . . . . . . . . . . . . .
Engine Component Locator (This illustration
is based on RHD model.) 6E–28. . . . . . . . . . . . . . Engine Component Locator Table 6E–29. . . . . . . .
Engine Component Locator Table 6E–31. . . . . . . .
Undercarriage Component Locator 6E–32. . . . . .
Undercarriage Component Locator Table
(Automatic Transmission) 6E–32. . . . . . . . . . . . . .
Undercarriage Component Locator Table
(Manual Transmission) 6E–33. . . . . . . . . . . . . . . .
Fuse and Relay Panel (Underhood
Electrical Center) 6E–33. . . . . . . . . . . . . . . . . . . . .
Sensors and Miscellaneous Component
Locators 6E–34. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Diagnosis 6E–37. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Strategy-Based Diagnostics 6E–37. . . . . . . . . . . . .
Strategy-Based Diagnostics 6E–37. . . . . . . . . . . . .
DTC Stored 6E–37
. . . . . . . . . . . . . . . . . . . . . . . . . . .
No DTC 6E–37. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
No Matching Symptom 6E–37. . . . . . . . . . . . . . . . .
Intermittents 6E–37. . . . . . . . . . . . . . . . . . . . . . . . . .
No Trouble Found 6E–37. . . . . . . . . . . . . . . . . . . . .
Verifying Vehicle Repair 6E–37. . . . . . . . . . . . . . . .
General Service Information 6E–38. . . . . . . . . . . . . .
OBD Serviceablity Issues 6E–38. . . . . . . . . . . . . . .
Maintenance Schedule 6E–38. . . . . . . . . . . . . . . . .
Visual / Physical Engine Compartment
Inspection 6E–38. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Basic Knowledge of Tools Required 6E–38. . . . . .
Serial Data Communications 6E–38. . . . . . . . . . . . . .
Class II Serial Data Communications 6E–38. . . . .
On-Board Diagnostic (OBD) 6E–39. . . . . . . . . . . . . .
On-Board Diagnostic Tests 6E–39. . . . . . . . . . . . .
Comprehensive Component Monitor
Diagnostic Operation 6E–39. . . . . . . . . . . . . . . . . .
Common OBD Terms 6E–40. . . . . . . . . . . . . . . . . .
The Diagnostic Executive 6E–40. . . . . . . . . . . . . . .
DTC Types 6E–41. . . . . . . . . . . . . . . . . . . . . . . . . . .
Verifying Vehicle Repair 6E–42. . . . . . . . . . . . . . . .
Reading Diagnostic Trouble Codes Using
A Tech 2 6E–42. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Tech 2 Tech 2 6E–43. . . . . . . . . . . . . . . . . . . . . . . . .
Tech 2 Features 6E–43. . . . . . . . . . . . . . . . . . . . . . .
Getting Started 6E–44. . . . . . . . . . . . . . . . . . . . . . . .
Operating Procedure (For Example) 6E–44. . . . .
DTC Modes 6E–45. . . . . . . . . . . . . . . . . . . . . . . . . . .
DTC Information Mode 6E–46. . . . . . . . . . . . . . . . .
Injector Balance Test 6E–46. . . . . . . . . . . . . . . . . . .
EGR Control Test 6E–47. . . . . . . . . . . . . . . . . . . . . .
Idle Air Control System Test 6E–48. . . . . . . . . . . . .

6E–19 ENGINE DRIVEABILITY AND EMISSIONS
PCM Pinout Table, 32-Way Red Connector – Row “B”
TS23344
PINPIN FunctionWire ColorIGN ONENG RUNRefer To
B15 Volt Reference “B”RED/YEL5.0 V5.0 VAppropriate Sensor
B2lgnition coilRED/WHT0.0 V0.1 VGeneral Description and
Operation
B3lgnition coilRED/BLK0.0 V0.1 VGeneral Description and
Operation
B4lgnition coilRED/GRN0.0 V0.1 VGeneral Description and
Operation
B5Not Used————
B6Not Used————
B7Exhaust Gas Recirculation
(EGR)YEL/RED0.6 V0.6 VGeneral Description and
Operation, Linear EGR
Control
B8Intake Air Temperature
(IAT) SensorYEL/GRN0.5-4.9 V
(depends on
temperature)0.5-4.9 V
(depends on
temperature)General Description and
Operation, IAT
B9Not Used————
B10Not Used————
B11Power Steering Pressure
(PSP) SwitchGRN/YELB+B+General Description and
Operation, PSP
B12Illuminated SwitchGRNB+B+Chassis Electrical
B13Class 2 DataORN/GRN0.0 V0.0 VDiagnosis, Class 2 Serial
Data
B14A/C ClutchGRN/BLKB+
(A/C OFF)B+
(A/C OFF)General Description and
Operation, A/C Clutch Circuit
Operation
B15ECM to ECU
CommunicationViolet0.0 V0.1 V—
B16Not Used————

6E–39 ENGINE DRIVEABILITY AND EMISSIONS
The data displayed on the other Tech 2 will appear the
same, with some exceptions. Some Tech 2s 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 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.
W h e n a d i a g n o s t i c t e s t r e p o r t s 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
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
Knock Sensor (KS)
Throttle Position (TP) sensor
Engine Coolant Temperature (ECT) sensor
Camshaft Position (CMP) sensor
Manifold Absolute Pressure (MAP) sensor
Mass Air Flow (MAF) sensorIn 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:
Idle Air Control (IAC) Motor
Electronic Transmission controls
A/C relays
Cooling fan relay
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.
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 (160F) and rise at least 22C
(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.

6E–40
ENGINE DRIVEABILITY AND EMISSIONS
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
Catalyst monitoring
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 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
MAF/MAP
barometric pressure
IAT
TP
fuel trim
TCC enabled
A/C on
Tr i p
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 diagnostic are run
when the vehicle is at operating temperature, some when
the vehicle first start 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 disables. 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 enables 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
following:
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
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 not 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) (“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 the it illuminate under
a strict set of guide lines.
Basically, the MIL is turned on when the PCM 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
emissionsrelated faults.
Extinguishing the MIL
When the MIL is on, the Diagnostic Executive will turn off
the MIL after
three 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 PCM memory (both Freeze Frame and Failure
Records) until
forty(40) warm-up cycles after no faults
have been completed.

6E–41 ENGINE DRIVEABILITY AND EMISSIONS
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 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 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 “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 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:
Ty p e 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
Ty p e B
Emissions related
“Armed” after one (1) trip with a fail
“Disarmed” 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
Type C (if the vehicle is so equipped)
Non-Emissions related
Requests illumination of the Service Lamp or the
service message on the Drive Information Center
(DIC) on the
first trip with a fail
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
Type D (Ty p e D non-emissions related are not utilized
on certain vehicle applications).
Non-Emissions related
Dose 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.
Storing and Erasing Freeze Frame Data and Failure
Records
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.
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
MAP/BARO
Injector Base Pulse Width
Loop Status

6E–42
ENGINE DRIVEABILITY AND EMISSIONS
Intermittent Malfunction Indicator Lamp
In the case of an “intermittent” fault, the MIL (“Check
Engine” lamp) may illuminate and then (after three trips)
go “OFF”. However, the corresponding diagnostic trouble
code will be stored in the memory. When unexpected
diagnostic trouble codes appear, check for an intermittent
malfunction.
A diagnostic trouble code may reset. Consult the
“Diagnostic Aids” 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). The DLC is used to
connect to Tech 2. Some common uses of Tech 2 are
listed below:
Identifying stored Diagnostic Trouble Codes (DTCs).
Clearing DTCs.
Performing output control tests.
Reading serial data.
TS24064
Verifying Vehicle Repair
Verification of vehicle repair will be more comprehensive
for vehicles with OBD 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 specific
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 systems. Failure to follow these steps
could result in unnecessary repairs.
Reading Diagnostic Trouble Codes Using
A Tech 2
The procedure for reading diagnostic trouble code(s) is to
used a diagnostic Tech 2. When reading DTC(s), follow
instructions supplied by Tech 2 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 “warm-up” 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 Tech 2 “clear DTCs”. When clearing DTCs
follow instructions supplied by the tool manufacturer.
When Tech 2 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 “OFF” 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).

6E–65 ENGINE DRIVEABILITY AND EMISSIONS
Knock Sensor Diagnosis
The Tech 2 has two data displays available for diagnosing
the knock sensor (KS) system. The two displays are
described as follows:
“Knock Retard” indicates the number of degrees that
the spark timing is being retarded due to a knock
condition.
“KS Noise Channel” indicates the current voltage level
being monitored on the noise channel.
DTCs P0325 and P0327 are designed to diagnose the KS
module, the knock sensor, and the related wiring. The
problems encountered with the KS system should set a
DTC. However, if no DTC was set but the KS system is
suspect because of a detonation complaint, refer to
Detonation/Spark Knock in Symptoms.
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 “OFF” 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.
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 p o r t i o n o f
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.
S o l e n o i d s a n d r e l a y s a r e t u r n e d “ O N ” a n d “ O F F ” b y t h e
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 (ETC) sensor
The intake air temperature (IAT) sensor
The transmission fluid temperature (TFT) sensor
The PCM provides the following sensors with a 5-volt
reference and a sensor ground signal:
The exhaust gas recirculating (EGR) pintle position
sensor
The throttle position (TP) sensor
The manifold absolute pressure (MAP) sensor
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:
P0108
P0113
P0118
P0123
P0560
P0712
P0406
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:
P0108
P0113
P0118
P0123
P0712
P0406
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:
P0107
P0122
In the 5-volt reference circuit A, between the PCM and the
splice, will cause one or more of the following DTCs to be
set:
P0122
In the 5-volt reference circuit B, between the PCM and the
splice, will cause one or more of the following DTCs to be
set:
P0107
Check for the following conditions: