2004 DAEWOO LACETTI engine controls

ENGINE CONTROLS 1F – 471
DAEWOO V–121 BL4
The EGR Decel Filter value should always be at –3 or low-
er. If the EGR Decel Filter number becomes more positive
(towards 0 or more), then the EGR system is becoming re-
stricted. Look for possible damage to the EGR pipe or for
a restriction caused by carbon deposits in the EGR pas-
sages or on the EGR valve.
Test Description
Number(s) below refer to the step number(s) on the Diag-
nostic Table.
1. The On–Board Diagnostic (EOBD) System Check
prompts the technician to complete some basic
checks and store the freeze frame and failure re-
cords data on the scan tool if applicable. This
creates an electronic copy of the data taken when
the malfunction occurred. The information is then
stored on the scan tool for later reference.
2. Commanding the EGR valve open determines
whether the EGR system can control the EGR
valve accurately and if the fault is present. The dif-
ference between the current and commanded posi-
tion is greater than 15%.
3. When the EGR valve electrical connector is discon-
nected, the scan tool should display the Actual
EGR Position as 0%. If it does not, the fault lies
either in the EGR signal circuit or the ECM.
4. There may be a slight delay for the voltage dis-
played on the DVM to change after the scan tool
commands the EGR valve to operate.
5. An open or poor connection condition may have
caused this DTC to set. Be sure to check the termi-
nals for being backed out, improperly formed or
damaged, and for poor tension.
7. The test light will have glowed brightly in the pre-
vious step if the EGR control circuit was shorted to
B+ and the Actual EGR Position on the scan toolwill display 100%. A test light that did not illuminate,
indicates that the circuit may be open or shorted to
ground.
9. If the EGR valve 5 volt reference is shorted to volt-
age, the digital voltmeter (DVM) will read battery
voltage and additional DTCs may be set and the
engine performance will be poor.
12. The replacement ECM must be reprogrammed.
Refer to the latest Techline procedure for ECM re-
programming.
13. Although the circuitry acted correctly when
checked, a problem may still lie within the terminals
which would not show up in probe type testing. Be
sure to check the terminals for being backed out,
improperly formed or damaged, and for poor ten-
sion.
17. All circuits to the EGR valve are OK at this point.
The fault lies internally in the EGR valve and, there-
fore, must be replaced. Be sure all gasket material
is removed from the EGR mounting surface. Even
a small amount of material may cause a DTC
P0401 to set.
18. Check the terminals for being backed out, improp-
erly formed or damaged, and for poor tension.
19. Clearing DTCs is a very important step for this
diagnostic. The clearing function allows the EGR
valve to relearn a new pintle position as the old
pintle position was inaccurate due to the failure that
caused the DTC. The DTC must be cleared with
the ignition ON, engine OFF or when the engine is
idling. If the ECM sees a EGR command, the new
pintle will not be learned.
20. If no malfunctions have been found at this point and
no additional DTCs were set, refer to ”Diagnostic
Aids” in this section for additional checks and infor-
mation.
DTC P0402 – Exhaust Gas Recirculation Excessive Flow
StepActionValue(s)YesNo
1Perform an On–Board Diagnostic (EOBD) System
Check.
Was the check performed?–Go to Step 2Go to
”On–Board
Diagnostic Sys-
tem Check”
21. Install a scan tool to the Data link Connector
(DLC).
2. Turn the ignition ON.
3. Command the Exhaust Gas Recirculation
(EGR) valve to the specific values.
Does the Actual EGR Position follow the Desired
EGR Position?25%, 50%,
75%, 100%Go to Step 19Go to Step 3
31. Turn the ignition OFF.
2. Disconnect the EGR valve.
3. Turn the ignition ON.
4. With a test light connected to B+, probe the
EGR valve wiring harness connector terminal
2.
Does the test light illuminate?–Go to Step 4Go to Step 5

1F – 472IENGINE CONTROLS
DAEWOO V–121 BL4
StepNo Yes Value(s) Action
41. Using a voltmeter, measure the voltage at the
EGR valve wiring harness connector terminal
1.
2. Command the EGR valve open with the scan
tool.
After command is raised, is the voltage displayed on
the voltmeter vary between specified value?0 to
5 VGo to Step 6Go to Step 7
5Repair the open or poor connection in the EGR
ground circuit as needed.
Is the repair complete?–Go to Step 19
6With a test light connected to ground, probe the EGR
valve wiring harness connector terminal 3.
Does the test light illuminate?–Go to Step 8Go to Step 9
7With a test light connected to ground, probe the EGR
valve wiring harness connector terminal 1, without
commanding the EGR valve with scan tool.
Dose the test light illuminate?–Go to Step 10Go to Step 11
8Check the signal circuit for a short to voltage and re-
pair as needed.
Is the repair complete?–Go to Step 19Go to Step 12
9With a voltmeter connected to the ground, probe the
5 volt reference circuit at terminal 4 of the EGR valve
wiring harness connector.
Is the voltage near the specified value?5 vGo to Step 13Go to Step 14
10Check the control circuit for a short to voltage and re-
pair as needed.
Is a repair necessary.–Go to Step 19Go to Step 12
11With a test light connected to B+ and again probe the
control circuit at terminal 1.
Dose the test light illuminate?–Go to Step 15Go to Step 16
121. Turn the ignition OFF.
2. Replace the Engine Control Module (ECM).
Is the repair complete?–Go to Step 19–
13Check the EGR ground circuit for poor connection or
proper terminal tension at the ECM and repair as
needed.
Is a repair necessary?–Go to Step 19Go to Step 17
14Check the 5 volt reference circuit for a short to volt-
age and repair as needed.
Is the repair necessary?–Go to Step 19Go to Step 12
15Check the control circuit 1 for short to ground and re-
pair as needed.
Is the repair necessary?–Go to Step 19Go to Step 12
16Check the control circuit at terminal 1 for an open or
poor connection at EGR valve connector and repair
as needed.
Is a repair necessary?–Go to Step 19Go to Step 18
171. Turn the ignition OFF.
2. Replace the EGR valve.
Is the repair complete?–Go to Step 19–

ENGINE CONTROLS 1F – 473
DAEWOO V–121 BL4
StepNo Yes Value(s) Action
18Check the ECM connector for a poor connection and
repair as needed.
Is the repair complete?–Go to Step 19–
191. Using the scan tool, clear the Diagnostic
Trouble Codes (DTCs).
2. Start the engine and idle at normal operating
temperature.
3. Operate the vehicle within the Conditions for
setting this DTC as specified in the supporting
text.
Does the scan tool indicate that this diagnostic has
run and passed?–Go to Step 20Go to Step 2
20Check if any additional DTCs are set.
Are any DTCs displayed that have not been diag-
nosed?–Go to
Applicable DTC
tableSystem OK

1F – 474IENGINE CONTROLS
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P0404
EXHAUST GAS RECIRCULATION OPEN VALVE POSITION
ERROR
Circuit Description
An Exhaust Gas Recirculation (EGR) system is used to
lower Nitrogen Oxide (NOx) emission levels caused by
high combustion temperatures. It accomplishes this by
feeding small amounts of exhaust gases back into the
combustion chamber. When the air/fuel mixture is diluted
with the exhaust gases, combustion temperatures are re-
duced
A linear EGR valve is used on this system. The linear EGR
valve is designed to accurately supply exhaust gases to
the engine without the use of intake manifold vacuum. The
valve controls exhaust flow going into the intake manifold
from the exhaust manifold through an orifice with an En-
gine Control Module (ECM) controlled pintle. The ECM
controls the pintle position using inputs from the Throttle
Position (TP) and Manifold Absolute Pressure (MAP) sen-
sors. The ECM then commands the EGR valve to operate
when necessary by controlling an ignition signal through
the ECM. This can be monitored on a scan tool as the De-
sired EGR Position.
The ECM monitors the results of its command through a
feedback signal. By sending a 5 volt reference and a
ground to the EGR valve, a voltage signal representing the
EGR valve pintle position is sent to the ECM. This feed-
back signal can also be monitored on a scan tool and is the
actual position of the EGR pintle. The Actual EGR Position
should always be near the commanded or Desired EGR
Position.
This Diagnostic Trouble Code (DTC) will detect an open
valve position.
Conditions for Setting the DTCS Difference between current and commended posi-
tion is greater than 15%.
S Desired EGR position is greater than 0.
S Change in Desired EGR is less than 3%.
S Engine is running.
S Ignition voltage is between 11.7 and 16 volts.
S Air temperature is greater than 3°C.
S DTCs P0112, P0113 P0405, P0406, and P0502 are
not set.
Action Taken When the DTC Sets
S The Malfunction Indicator Lamp (MIL) will illumi-
nate, after three concecutive ignition cycle with a
fail.
S The ECM will record operating conditions at the
time the diagnostic fails. This information will be
stored in the Freeze Frame and Failure Records
buffers.
S A history Diagnostic Trouble Code (DTC) is stored.
S EGR is disabled.
Conditions for Clearing the MIL/DTC
S The MIL will turns off after four consecutive ignition
cycles in which the diagnostic runs without a fault.
S A history DTC will clear after 40 consecutive warm–
up cycles without a fault.
S DTC(s) can be cleared by using the scan tool.
S Disconnecting the ECM battery feed for more than
10 seconds.
Diagnostic Aids
Due to moisture associated with exhaust systems, the
EGR valve may freeze and stick in cold weather at times.
After the vehicle is brought into a warm shop for repairs,
the valve warms and the problem disappears. By watching

ENGINE CONTROLS 1F – 475
DAEWOO V–121 BL4
the Actual EGR and Desired EGR Positions on a cold ve-
hicle with a scan tool, the fault can be easily verified.
Check the freeze frame data to determine if the DTC set
when the vehicle was cold by viewing the Engine Coolant
Temperature (ECT).
Test Description
Number(s) below refer to the step number(s) on the Diag-
nostic Table.
1. The On–Board Diagnostic (EOBD) System Check
prompts the technician to complete some basic
checks and store the freeze frame and failure re-
cords data on the scan tool if applicable. This
creates an electronic copy of the data taken when
the malfunction occurred. The information is then
stored on the scan tool for later reference.
2. Commanding the EGR valve open determines
whether the EGR system can control the EGR
valve accurately and if the fault is present. The dif-
ference between the current and commanded posi-
tion is greater than 15%.
3. When the EGR valve electrical connector is discon-
nected, the scan tool should display the Actual
EGR Position as 0%. If it does not, the fault lies
either in the EGR signal circuit or the ECM.
4. There may be a slight delay for the voltage dis-
played on the DVM to change after the scan tool
commands the EGR valve to operate.
5. An open or poor connection condition may have
caused this DTC to set. Be sure to check the termi-
nals for being backed out, improperly formed or
damaged, and for poor tension.
7. The test light will have glowed brightly in the pre-
vious step if the EGR control circuit was shorted to
B+ and the Actual EGR Position on the scan toolwill display 100%. A test light that did not illuminate,
indicates that the circuit may be open or shorted to
ground.
9. If the EGR valve 5 volt reference is shorted to volt-
age, the digital voltmeter (DVM) will read battery
voltage and additional DTCs may be set and the
engine performance will be poor.
12. The replacement ECM must be reprogrammed.
Refer to the latest Techline procedure for ECM re-
programming.
13. Although the circuitry acted correctly when
checked, a problem may still lie within the terminals
which would not show up in probe type testing. Be
sure to check the terminals for being backed out,
improperly formed or damaged, and for poor ten-
sion.
17. All circuits to the EGR valve are OK at this point.
The fault lies internally in the EGR valve and, there-
fore, must be replaced. Be sure all gasket material
is removed from the EGR mounting surface. Even
a small amount of material may cause a DTC
P0401 to set.
18. Check the terminals for being backed out, improp-
erly formed or damaged, and for poor tension.
19. Clearing DTCs is a very important step for this
diagnostic. The clearing function allows the EGR
valve to relearn a new pintle position as the old
pintle position was inaccurate due to the failure that
caused the DTC. The DTC must be cleared with
the ignition ON, engine OFF or when the engine is
idling. If the ECM sees a EGR command, the new
pintle will not be learned.
20. If no malfunctions have been found at this point and
no additional DTCs were set, refer to ”Diagnostic
Aids” in this section for additional checks and infor-
mation.
DTC P0404 – Exhaust Gas Recirculation Open Valve Position Error
StepActionValue(s)YesNo
1Perform an On–Board Diagnostic (EOBD) System
Check.
Was the check performed?–Go to Step 2Go to
”On–Board
Diagnostic Sys-
tem Check”
21. Install a scan tool to the Data Link Connector
(DLC).
2. Turn the ignition ON.
3. Command the Exhaust Gas Recirculation
(EGR) valve to the specific values.
Does the Actual EGR Position follow the Desired
EGR Position?25%, 50%,
75%, 100%Go to Step 19Go to Step 3
31. Turn the ignition OFF.
2. Disconnect the EGR valve.
3. Turn the ignition ON.
4. With a test light connected to B+, probe the
EGR valve wiring harness connector terminal
2.
Does the test light illuminate?–Go to Step 4Go to Step 5

1F – 476IENGINE CONTROLS
DAEWOO V–121 BL4
StepNo Yes Value(s) Action
41. Using a voltmeter, measure the voltage at the
EGR valve wiring harness connector terminal
1.
2. Command the EGR valve open with the scan
tool.
After command is raised, is the voltage displayed on
the voltmeter vary between specified value?0 to
5 VGo to Step 6Go to Step 7
5Repair the open or poor connection in the EGR
ground circuit as needed.
Is the repair complete?–Go to Step 19–
6With a test light connected to ground, probe the EGR
valve wiring harness connector terminal 3.
Dose the test light illuminate?–Go to Step 8Go to Step 9
7With a test light connected to ground, probe the EGR
valve wiring harness connector terminal 1, without
commanding the EGR valve with scan tool.
Dose the test light illuminate?–Go to Step 10Go to Step 11
8Check the signal circuit for a short to voltage and re-
pair as needed.
Is a repair necessary?–Go to Step 19Go to Step 12
9With a voltmeter connected to the ground, probe the
5 volt reference circuit at terminal 4 of the EGR valve
wiring harness connector.
Is the voltage near the specified value?5 vGo to Step 13Go to Step 14
10Check the control circuit for a short to voltage and re-
pair as needed.
Is a repair complete?–Go to Step 19Go to Step 12
11With a test light connected to B+ and again probe the
control circuit at terminal 1.
Dose the test light illuminate?–Go to Step 15Go to Step 16
121. Turn the ignition OFF.
2. Replace the Engine Control Module (ECM).
Is the repair complete?–Go to Step 19–
13Check the EGR ground circuit for poor connection or
proper terminal tension at the ECM and repair as
needed.
Is the repair complete?–Go to Step 19Go to Step 17
14Check the 5 volt reference circuit for a short to volt-
age and repair as needed.
Is the repair complete?–Go to Step 19Go to Step 12
15Check the control circuit at terminal 1 for short to
ground and repair as needed.
Is the repair complete?–Go to Step 19Go to Step 12
16Check the control circuit at terminal 1 for an open or
poor connection at EGR valve connector and repair
as needed.
Is the repair complete?–Go to Step 19Go to Step 18
171. Turn the ignition OFF.
2. Replace the EGR valve.
Is the repair complete?–Go to Step 19–

ENGINE CONTROLS 1F – 477
DAEWOO V–121 BL4
StepNo Yes Value(s) Action
18Check the ECM connector for a poor connection and
repair as needed.
Is the repair complete?–Go to Step 19–
191. Using the scan tool, clear the Diagnostic
Trouble Codes (DTCs).
2. Start the engine and idle at normal operating
temperature.
3. Operate the vehicle within the Conditions for
setting this DTC as specified in the supporting
text.
Does the scan tool indicate that this diagnostic has
run and passed?–Go to Step 20Go to Step 2
20Check if any additional DTCs are set.
Are any DTCs displayed that have not been diag-
nosed?–Go to
Applicable DTC
tableSystem OK

1F – 478IENGINE CONTROLS
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P0405
EXHAUST GAS RECIRCULATION PINTLE POSITION LOW
VOLTAGE
Circuit Description
An Exhaust Gas Recirculation (EGR) system is used to
lower Nitrogen Oxide (NOx) emission levels caused by
high combustion temperatures. It accomplishes this by
feeding small amounts of exhaust gases back into the
combustion chamber. When the air/fuel mixture is diluted
with the exhaust gases, combustion temperatures are re-
duced
A linear EGR valve is used on this system. The linear EGR
valve is designed to accurately supply exhaust gases to
the engine without the use of intake manifold vacuum. The
valve controls exhaust flow going into the intake manifold
from the exhaust manifold through an orifice with an En-
gine Control Module (ECM) controlled pintle. The ECM
controls the pintle position using inputs from the Throttle
Position (TP) and Manifold Absolute Pressure (MAP) sen-
sors. The ECM then commands the EGR valve to operate
when necessary by controlling an ignition signal through
the ECM. This can be monitored on a scan tool as the De-
sired EGR Position.
The ECM monitors the results of its command through a
feedback signal. By sending a 5 volt reference and a
ground to the EGR valve, a voltage signal representing the
EGR valve pintle position is sent to the ECM. This feed-
back signal can also be monitored on a scan tool and is the
actual position of the EGR pintle. The Actual EGR Position
should always be near the commanded or Desired EGR
Position. This diagnostic Trouble Code (DTC) will detect
an open or short circuit.Conditions for Setting the DTC
S EGR position signal is less than 2%.
S Ignition voltage is between 11.7 and 16 volts.
S Fail condition last more than 10 seconds.
Action Taken When the DTC Sets
S The Malfunction Indicator Lamp (MIL) will illuminate
after three consecutive ignition cycle with a fail.
S The ECM will record operating conditions at the
time the diagnostic fails. This information will be
stored in the Freeze Frame and Failure Records
buffers.
S A history Diagnostic Trouble Code (DTC) is stored.
S EGR is disabled.
Conditions for Clearing the MIL/DTC
S The MIL will turns off after four consecutive ignition
cycles in which the diagnostic runs without a fault.
S A history DTC will clear after 40 consecutive warm–
up cycles without a fault.
S DTC(s) can be cleared by using the scan tool.
S Disconnecting the ECM battery feed for more than
10 seconds.
Diagnostic Aids
Due to moisture associated with exhaust systems, the
EGR valve may freeze and stick in cold weather at times.
After the vehicle is brought into a warm shop for repairs,
the valve warms and the problem disappears. By watching
the Actual EGR and Desired EGR Positions on a cold ve-
hicle with a scan tool, the fault can be easily verified.
Check the freeze frame data to determine if the DTC set
when the vehicle was cold by viewing the Engine Coolant
Temperature (ECT).