2004 DAEWOO LACETTI OBD port

1F – 632IENGINE CONTROLS
DAEWOO V–121 BL4
READING DIAGNOSTIC TROUBLE
CODES
The procedure for reading diagnostic trouble code(s) is to
use a diagnostic scan tool. When reading Diagnostic
Trouble Codes (DTCs), follow the instructions supplied by
tool manufacturer.
DTC Modes
On On–Board Diagnostic (EOBD) passenger cars there
are five options available in the scan tool DTC mode to dis-
play the enhanced information available. A description of
the new modes, DTC Info and Specific DTC, follows. After
selecting DTC, the following menu appears:
S DTC Info.
S Specific DTC.
S Freeze Frame.
S Fail Records (not all applications).
S Clear Info.
The following is a brief description of each of the sub me-
nus in DTC Info and Specific DTC. The order in which they
appear here is alphabetical and not necessarily the way
they will appear on the scan tool.
DTC Information Mode
Use the DTC info mode to search for a specific type of
stored DTC information. There are seven choices. The
service manual may instruct the technician to test for
DTCs in a certain manner. Always follow published service
procedures.
To get a complete description of any status, press the ”En-
ter” key before pressing the desired F–key. For example,
pressing ”Enter” then an F–key will display a definition of
the abbreviated scan tool status.
DTC Status
This selection will display any DTCs that have not run dur-
ing the current ignition cycle or have reported a test failure
during this ignition up to a maximum of 33 DTCs. DTC
tests which run and pass will cause that DTC number to
be removed from the scan tool screen.
Fail This Ign. (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
ECM’s history memory. It will not display type CNL DTCs
that have not requested the Malfunction Indicator Lamp
(MIL). It will display all type A, B and E DTCs that have re-
quested 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 Fail
This selection will display only DTCs that failed the last
time the test ran. The last test may have run during a pre-
vious ignition cycle if a type A or type B DTC is displayed.
For type C and type D DTCs, the last failure must have oc-
curred during the current ignition cycle to appear as Last
Test Fail.
MIL Request
This selection will display only DTCs that are requesting
the MIL. Type C and type D DTCs cannot be displayed us-
ing this option. This selection will report type B DTCs only
after the MIL has been requested.
Not Run SCC (Not Run Since Code Clear)
This option will display up to 33 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 Fail SCC (Test Failed Since Code
Clear)
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.
Specific DTC Mode
This mode is used to check the status of individual diag-
nostic tests by DTC number. This selection can be ac-
cessed if a DTC has passed, failed or both. Many EOBD
DTC mode descriptions are possible because of the ex-
tensive amount of information that the diagnostic execu-
tive monitors regarding each test. Some of the many pos-
sible descriptions follow with a brief explanation.
The ”F2” key is used, in this mode, to display a description
of the DTC. The ”Yes” and ”No” keys may also be used to
display more DTC status information. This selection will
only allow entry of DTC numbers that are supported by the
vehicle being tested. If an attempt is made to enter DTC
numbers for tests which the diagnostic executive does not
recognize, the requested information will not be displayed
correctly and the scan tool may display an error message.
The same applies to using the DTC trigger option in the
Snapshot mode. If an invalid DTC is entered, the scan tool
will not trigger.
Failed Last Test
This message display indicates that the last diagnostic
test failed for the selected DTC. For type A and type B
DTCs, this message will be displayed during subsequent
ignition cycles until the test passes or DTCs are cleared.
For type C and type D DTCs, this message will clear when
the ignition is cycled.
Failed Since Clear
This message display indicates that the DTC has failed at
least once within the last 40 warm–up cycles since the last
time DTCs were cleared.

1F – 634IENGINE CONTROLS
DAEWOO V–121 BL4
A rough road sensor, or G sensor, works together with the
misfire detection system. The G sensor produces a volt-
age that varies along with the intensity of road vibrations.
When the ECM detects a rough road, the misfire detection
system is temporarily disabled.
Misfire Counters
Whenever a cylinder misfires, the misfire diagnostic
counts the misfire and notes the crankshaft position at the
time the misfire occurred. These ”misfire counters” are ba-
sically a file on each engine cylinder. A current and a histo-
ry misfire counter are maintained for each cylinder. The
misfire current counters (Misfire Cur #1–4) indicate the
number of firing events out of the last 200 cylinder firing
events which were misfires. The misfire current counter
will display real time data without a misfire Diagnostic
Trouble Code (DTC) stored. The misfire history counters
(Misfire Hist #1–4) indicate the total number of cylinder fir-
ing events which were misfires. The misfire history count-
ers will display 0 until the misfire iagnostic has failed and
a DTC P0300 is set. Once the misfire DTC P0300 is set,
the misfire history counters will be updated every 200 cyl-
inder 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 report-
ing a 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 incor-
rectly identify which cylinder is misfiring.
Use diagnostic equipment to monitor misfire counter data
on On–Board Diagnostic (EOBD) compliant vehicles.
Knowing which specific cylinder(s) misfired can lead to the
root cause, even when dealing with amultiple cylinder mis-
fire. Using the information in the misfire counters, identify
which cylinders are misfiring. If the counters indicate cylin-
ders numbers 1 and 4 misfired, look for a circuit or compo-
nent common to both cylinders number 1 and 4.
The misfire diagnostic may indicate a fault due to a tempo-
rary fault not necessarily caused by a vehicle emission
system malfunction. Examples include the following
items:
S Contaminated fuel.S Low fuel.
S Fuel–fouled spark plugs.
S Basic engine fault.
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 val-
ues 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 Evaporative
(EVAP) Emission canister. In order to meet EOBD require-
ments, 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 HO2S2
DTC may set). Use a scan tool 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 HO2S2
DTC may set). Use a scan tool to observe fuel trim counts
while the problem is occurring.

5A1 – 102IZF 4 HP 16 AUTOMATIC TRANSAXLE
DAEWOO V–121 BL4
DTC P0720 – Output Speed Sensor(OSS) Circuit Malfunction
StepActionValue(s)YesNo
1Perform an On–Board Diagnostic (EOBD) System
Check.
Is the check completed?–Go to Step 2Go to ”On–
Board Diagnos-
tic System
Check”
21. Install the scan tool.
2. Turn the ignition ON and record then clear
DTC(s), then turn the ignition OFF.
3. Raise and support the drive wheels, then start
the engine.
4. Gear position is D and observe the output
speed on the scan tool.
Is the speed within the values shown?190~9,762rpmGo to ”Diag-
nostic Aids”Go to Step 3
31. Turn the ignition OFF.
2. Disconnect the transaxle wiring connector.
3. Measure the resistance between terminals 1
and 2 of the transaxle wiring connector.
Is the resistance within the values shown?
Go to Step 9Go to Step 4
41. Remove the oil pan.
2. Disconnect the output speed sensor wiring
connector.
3. Measure the resistance between terminal 1 of
the output speed sensor wiring connector and
terminal 1 of the transaxle wiring connector.
4. Measure the resistance between terminal 2 of
the output speed sensor wiring connector and
terminal 2 of the transaxle wiring connector.
Is the resistance within the values shown?0ΩGo to Step 6Go to Step 5
5Repair the malfunctioning terminals as necessary.
Is the action complete?–System OK–
61. Turn the ignition ON.
2. Measure the voltage of terminal 1.
3. Measure the voltage of terminal 2.
Is the voltage within the values shown?11–14VGo to Step 7Go to Step 8
7Repair the malfunctioning terminals as necessary.
Is the action complete?–System OK–
8Replace the output speed sensor.
Is the action complete?–System OK–
91. Disconnect the transaxle wiring connector and
TCM connector.
2. Measure the resistance between terminal 1 of
the transaxle wiring connector and terminal
B10 of the TCM wiring connector.
3. Measure the resistance between terminal 2 of
the transaxle wiring connector and terminal B5
of the TCM wiring connector.
Is the resistance within the values shown?0ΩGo to Step 11Go to Step 10
10Repair the malfunctioning terminals as necessary.
Is the action complete?–System OK–

ZF 4 HP 16 AUTOMATIC TRANSAXLE 5A1 – 105
DAEWOO V–121 BL4
DTC P0721 – Output Speed Sensor(OSS) Circuit
Range/Performance
StepActionValue(s)YesNo
1Perform an On–Board Diagnostic (EOBD) System
Check.
Is the check completed?–Go to Step 2Go to ”On–
Board Diagnos-
tic System
Check”
21. Install the scan tool.
2. Turn the ignition ON and record then clear
DTC(s), then turn the ignition OFF.
3. Raise and support the drive wheels, then start
the engine.
4. Gear position is D and observe the output
speed on the scan tool.
Is the speed within the values shown?190~9,762rpmGo to ”Diag-
nostic Aids”Go to Step 3
31. Turn the ignition LOCK.
2. Disconnect the transaxle wiring connector.
3. Measure the resistance between terminals 1
and 2 of the transaxle wiring connector.
Is the resistance within the values shown?
Go to Step 9Go to Step 4
41. Remove the oil pan.
2. Disconnect the output speed sensor wiring
connector.
3. Measure the resistance between terminal 1 of
the output speed sensor wiring connector and
terminal 1 of the transaxle wiring connector.
4. Measure the resistance between terminal 2 of
the output speed sensor wiring connector and
terminal 2 of the transaxle wiring connector.
Is the resistance within the values shown?0ΩGo to Step 6Go to Step 5
5Repair the malfunctioning terminals as necessary.
Is the action complete?–System OK–
61. Turn the ignition ON.
2. Measure the voltage of terminal 1.
3. Measure the voltage of terminal 2.
Is the voltage within the values shown?11–14VGo to Step 7Go to Step 8
7Repair the malfunctioning terminals as necessary.
Is the action complete?–System OK–
8Replace the input speed sensor.
Is the action complete?–System OK–
91. Disconnect the transaxle wiring connector and
TCM connector.
2. Measure the resistance between terminal 1 of
the transaxle wiring connector and terminal
B10 of the TCM wiring connector.
3. Measure the resistance between terminal 2 of
the transaxle wiring connector and terminal B5
of the TCM wiring connector.
Is the resistance within the values shown?0ΩGo to Step 11Go to Step 10
10Repair the malfunctioning terminals as necessary.
Is the action complete?–System OK–

5A1 – 108IZF 4 HP 16 AUTOMATIC TRANSAXLE
DAEWOO V–121 BL4
DTC P0722 – Output Speed Sensor(OSS) Circuit No Signal
StepActionValue(s)YesNo
1Perform an On–Board Diagnostic (EOBD) System
Check.
Is the check completed?–Go to Step 2Go to ”On–
Board Diagnos-
tic System
Check”
21. Install the scan tool.
2. Turn the ignition ON and record then clear
DTC(s), then turn the ignition OFF.
3. Raise and support the drive wheels, then start
the engine.
4. Gear position is D and observe the output
speed on the scan tool.
Is the speed within the values shown?190~9,762rpmGo to ”Diag-
nostic Aids”Go to Step 3
31. Turn the ignition LOCK.
2. Disconnect the transaxle wiring connector.
3. Measure the resistance between terminals 1
and 2 of the transaxle wiring connector.
Is the resistance within the values shown?
Go to Step 9Go to Step 4
41. Remove the oil pan.
2. Disconnect the output speed sensor wiring
connector.
3. Measure the resistance between terminal 1 of
the output speed sensor wiring connector and
terminal 1 of the transaxle wiring connector.
4. Measure the resistance between terminal 2 of
the output speed sensor wiring connector and
terminal 2 of the transaxle wiring connector.
Is the resistance within the values shown?0ΩGo to Step 6Go to Step 5
5Repair the malfunctioning terminals as necessary.
Is the action complete?–System OK–
61. Turn the ignition ON.
2. Measure the voltage of terminal 1.
3. Measure the voltage of terminal 2.
Is the voltage within the values shown?11–14VGo to Step 7Go to Step 8
7Repair the malfunctioning terminals as necessary.
Is the action complete?–System OK–
8Replace the output speed sensor.
Is the action complete?–System OK–
91. Disconnect the transaxle wiring connector and
TCM connector.
2. Measure the resistance between terminal 1 of
the transaxle wiring connector and terminal
B10 of the TCM wiring connector.
3. Measure the resistance between terminal 2 of
the transaxle wiring connector and terminal B5
of the TCM wiring connector.
Is the resistance within the values shown?0ΩGo to Step 11Go to Step 10
10Repair the malfunctioning terminals as necessary.
Is the action complete?–System OK–