Section 5 DAEWOO LACETTI 2004 Service Repair Manual

1F – 154IENGINE CONTROLS
DAEWOO V–121 BL4
Diagnostic Aids
Normal scan tool voltage varies between 0.15 to 8.5mV
while in Closed Loop. If DTC P0140 is intermittent, refer
to ”Intermittents” in this section.
DTC P0140 – Rear Heated Oxygen Sensor No Activity
StepActionValue(s)YesNo
1Perform an Euro On–Board Diagnostic (EOBD)
System Check.
Is the system check complete?–Go to Step 2Go to
”On–Board
Diagnostic Sys-
tem Check”
21. Run the engine to above the specified operat-
ing temperature.
2. Install a scan tool.
3. Operate the engine above the specified rpm for
2 minuets.
Does the scan tool the indicate Closed Loop?80°C(176°F)
1,200rpmGo to Step 3Go to Step 4
31. Turn the Turn the ignition switch to ON.
2. Review the Freeze Frame data and note the
parameters.
3. Operate the vehicle within the freeze frame
conditions and Conditions for Setting the DTC
as noted?
Does the scan tool the indicate Closed Loop?–Go to Step 12Go to Step 4
4Disconnect the Heated O2 sensor connector and
jumper the Heated O2 sensor low circuit, terminal 3
to ground.
Is the HO2 voltage below the specified value and
does the scan tool indicate the heated oxygen sen-
sor heater voltage within the specified value?0.5VGo to Step 5Go to Step 6
5Check the Heated O2 sensor connector for malfunc-
tion terminals or poor connection and repair as nec-
essary.
Is repair necessary?–Go to Step 12Go to Step 9
61. Turn the ignition switch to On.
2. Remove the jumper wire.
3. Using a digital voltmeter(DVM), measure the
voltage between the Heated O2 sensor signal
circuit, terminal 4 to ground.
Does the Heated O2 sensor voltage measure above
the specified value?0.6VGo to Step 10Go to Step 9
7Does the Heated O2 sensor voltage measure below
the specified value?0.3VGo to Step 11Go to Step 8
8Check the Heated O2 sensor ground circuit, termi-
nal 3 for an open or poor connection and repair as
necessary.
Is repair necessary?–Go to Step 12Go to Step 8
9Check the Heated O2 sensor signal circuit, terminal
4 for an open or poor connection and repair as nec-
essary.
Is repair necessary?–Go to Step 12Go to Step 8

1F – 160IENGINE CONTROLS
DAEWOO V–121 BL4
StepNo Yes Value(s) Action
8Lean condition is not present.
Does a driveability problem exist?–Go to
”Symptom
Diagnosis”Go to Step 16
91. Visually/physically inspect the following items
for vacuum leaks:
S Intake manifold.
S Throttle body.
S Injector O–rings.
2. Repair any leaks found as necessary.
Is the repair complete?–Go to Step 16Go to Step 16
10Allow the engine to idle.
Are the Idle Air Control (IAC) counts above the spe-
cified value?5Go to Step 11Go to Step 12
11Check the fuel for excessive water, alcohol, or other
contaminants and correct the contaminated fuel
condition if present.
Is the repair complete?–Go to Step 16Go to Step 13
12Check the IAC valve performance. Refer to ”DTC
P0506 Idle Speed RPM Lower Than Desired Idle
Speed” or ”DTC P0507 Idle Speed RPM Higher
Than Desired Idle Speed” in this section and repair
as necessary.
Is the repair complete?–Go to Step 16Go to Step 13
131. Connect a fuel pressure gauge to the fuel sys-
tem.
2. Turn the ignition OFF for at least 10 seconds.
3. Turn the ignition ON, with the engine OFF. The
fuel pump will run for approximately 2–3 sec-
onds. It may be necessary to cycle the ignition
switch ON more than once to obtain maximum
fuel pressure.
4. Note the fuel pressure with the fuel pump run-
ning. The pressure should be within the speci-
fied value. When the fuel pump stops, the pres-
sure may vary slightly then hold steady.
Is the fuel pressure steady and does the fuel pres-
sure hold?241–276 kPa
(35–40 psi)Go to Step 14Go to
”Fuel System
Diagnosis”
141. Start and idle the engine at normal operating
temperature.
2. The fuel pressure noted in the above step
should drop by the indicated value.
Does the fuel pressure drop by the indicated value?21–69 kPa
(3–10 psi)Go to
”Fuel Injector
Balance Test”Go to
”Fuel System
Diagnosis”
15Replace the MAP sensor.
Is the action complete?–Go to Step 16–

ENGINE CONTROLS 1F – 163
DAEWOO V–121 BL4
StepNo Yes Value(s) Action
3With the engine running, operate the vehicle until the
LOOP STATUS indicates closed.
Is the Long Term Fuel Trim value above the specified
value?–30%Go to Step 4Go to Step 5
41. Turn the ignition switch ON, with the engine
OFF.
2. Review the Freeze Frame data and note the
parameters.
3. Operate the vehicle within the Freeze Frame
conditions and Conditions for Setting The DTC
as noted.
Does the Long Term Fuel Trim value above the spe-
cified value while operating under the specified con-
ditions?–30%Go to Step 21Go to Step 5
5Visually/physically check the air cleaner filter for ex-
cessive dirt or being plugged and repair as needed.
Is the repair complete?–Go to Step 21Go to Step 6
6Visually/physically check the air intake system for
collapsed or restricted and repair as needed.
Is the repair complete?–Go to Step 21Go to Step 7
7Inspect the throttle body inlet for damaged or foreign
objects which may partially block the airflow and re-
pair as needed.
Is the repair complete?–Go to Step 21Go to Step 8
81. Turn the ignition OFF.
2. Inspect the throttle bore, throttle plate and Idle
Air Control (IAC) passages for clocking and
foreign objects and repair as needed.
Is the repair complete?–Go to Step 21Go to Step 9
9Start the engine with the vehicle in park or neutral
and A/C off and note the idle quality.
Is a low or unsteady idle being experienced?–Go to Step 10Go to Step 12
10Idle the engine.
Are the IAC counts below the specified value?100Go to Step 12Go to Step 11
111. Turn the ignition OFF.
2. Disconnect the Manifold Absolute Pressure
(MAP) sensor electrical connector.
3. Start the engine.
4. Operate the vehicle in Closed Loop while moni-
toring the Long Term Fuel Trim value.
Does the Long Term Fuel Trim value increase above
the specified value?–30%Go to Step 20Go to Step 12
12Check the IAC valve performance. Refer to ”DTC
P0506 Idle Speed RPM Lower Than Desired Idle
Speed” or ”DTC P0507 Idle Speed RPM Higher
Than Desired Idle Speed” in this section and repair
as necessary.
Is the repair complete?–Go to Step 21Go to Step 13

ENGINE CONTROLS 1F – 171
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P0261
INJECTOR 1 LOW VOLTAGE
Circuit Description
The transaxle control module(TCM)/engine control mod-
ule (ECM) has four individual injector driver circuits, each
of which controls an injector. When a driver circuit is
grounded by the ECM, the injector is activated. The ECM
monitors the current in each driver circuit. The ECM mea-
sures a voltage drop through a fixed resistor and controls
it. The voltage on each driver is monitored to detect a fault.
If the voltage is not what the ECM expects to monitor on
the circuit, a Diagnostic Trouble Code (DTC) is set. This
DTC detects a low voltage and/or an open circuit and high
voltage conditions for low–side drive injector outputs.
Conditions for Setting the DTC
S The injector 1 circuit is an open or a short to ground
condition exists.
Action Taken When the DTC Sets
S The Malfunction Indicator Lamp (MIL) will illumi-
nate.
S The ECM will record operating conditions at the
time the diagnostic fails. This information will be
stored in the Freeze Frame and Records buffers.S A history DTC is stored.
Conditions for Clearing the MIL/DTC
S The MIL will turn off after 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 10 sec-
onds.
Diagnostic Aids
An injector driver circuit that is open or shorted to voltage
will causes a DTC P0261 to set. It will also cause a misfire
due to an inoperative injector. A misfire DTC should also
be set indicating which injector is inoperative.
Long–term and short–terms fuel trims that are excessively
high or low are a good indication that an injector is mal-
functioning. Refer to ”Fuel Injector Balance Test” in this
section to check for malfunctioning injectors.
The injector resistance tested at the ECM connection is
slightly more than it tested directly at the injector because
it includes resistance of the harness wires. The normal val-
ue is about 13.5W.

ENGINE CONTROLS 1F – 173
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P0262
INJECTOR 1 HIGH VOLTAGE
Circuit Description
The transaxle control module(TCM)/engine control mod-
ule (ECM) has four individual injector driver circuits, each
of which controls an injector. When a driver circuit is
grounded by the ECM, the injector is activated. The ECM
monitors the current in each driver circuit. The ECM mea-
sures a voltage drop through a fixed resistor and controls
it. The voltage on each driver is monitored to detect a fault.
If the voltage is not what the ECM expects to monitor on
the circuit, a Diagnostic Trouble Code (DTC) is set. This
DTC detects a low voltage and/or an open circuit and high
voltage conditions for low–side drive injector outputs.
Conditions for Setting the DTC
S The injector 1 circuit is a short to battery condition
exists.
Action Taken When the DTC Sets
S The Malfunction Indicator Lamp (MIL) will illumi-
nate.
S The ECM will record operating conditions at the
time the diagnostic fails. This information will be
stored in the Freeze Frame and Records buffers.S A history DTC is stored.
Conditions for Clearing the MIL/DTC
S The MIL will turn off after 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 10 sec-
onds.
Diagnostic Aids
An injector driver circuit that is open or shorted to voltage
will causes a DTC P0262 to set. It will also cause a misfire
due to an inoperative injector. A misfire DTC should also
be set indicating which injector is inoperative.
Long–term and short–terms fuel trims that are excessively
high or low are a good indication that an injector is mal-
functioning. Refer to ”Fuel Injector Balance Test” in this
section to check for malfunctioning injectors.
The injector resistance tested at the ECM connection is
slightly more than it tested directly at the injector because
it includes resistance of the harness wires. The normal val-
ue is about 13.5W.

ENGINE CONTROLS 1F – 175
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P0264
INJECTOR 2 LOW VOLTAGE
Circuit Description
The transaxle control module(TCM)/engine control mod-
ule (ECM) has four individual injector driver circuits, each
of which controls an injector. When a driver circuit is
grounded by the ECM, the injector is activated. The ECM
monitors the current in each driver circuit. The ECM mea-
sures a voltage drop through a fixed resistor and controls
it. The voltage on each driver is monitored to detect a fault.
If the voltage is not what the ECM expects to monitor on
the circuit, a Diagnostic Trouble Code (DTC) is set. This
DTC detects a low voltage and/or an open circuit and high
voltage conditions for low–side drive injector outputs.
Conditions for Setting the DTC
S The injector 2 circuit is an open or a short to ground
condition exists.
Action Taken When the DTC Sets
S The Malfunction Indicator Lamp (MIL) will illumi-
nate.
S The ECM will record operating conditions at the
time the diagnostic fails. This information will be
stored in the Freeze Frame and Records buffers.S A history DTC is stored.
Conditions for Clearing the MIL/DTC
S The MIL will turn off after 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 10 sec-
onds.
Diagnostic Aids
An injector driver circuit that is open or shorted to voltage
will causes a DTC P0264 to set. It will also cause a misfire
due to an inoperative injector. A misfire DTC should also
be set indicating which injector is inoperative.
Long–term and short–terms fuel trims that are excessively
high or low are a good indication that an injector is mal-
functioning. Refer to ”Fuel Injector Balance Test” in this
section to check for malfunctioning injectors.
The injector resistance tested at the ECM connection is
slightly more than it tested directly at the injector because
it includes resistance of the harness wires. The normal val-
ue is about 13.5W.

ENGINE CONTROLS 1F – 177
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P0265
INJECTOR 2 HIGH VOLTAGE
Circuit Description
The transaxle control module(TCM)/engine control mod-
ule (ECM) has four individual injector driver circuits, each
of which controls an injector. When a driver circuit is
grounded by the ECM, the injector is activated. The ECM
monitors the current in each driver circuit. The ECM mea-
sures a voltage drop through a fixed resistor and controls
it. The voltage on each driver is monitored to detect a fault.
If the voltage is not what the ECM expects to monitor on
the circuit, a Diagnostic Trouble Code (DTC) is set. This
DTC detects a low voltage and/or an open circuit and high
voltage conditions for low–side drive injector outputs.
Conditions for Setting the DTC
S The injector 2 circuit is a short to battery condition
exists.
Action Taken When the DTC Sets
S The Malfunction Indicator Lamp (MIL) will illumi-
nate.
S The ECM will record operating conditions at the
time the diagnostic fails. This information will be
stored in the Freeze Frame and Records buffers.S A history DTC is stored.
Conditions for Clearing the MIL/DTC
S The MIL will turn off after 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 10 sec-
onds.
Diagnostic Aids
An injector driver circuit that is open or shorted to voltage
will causes a DTC P0265 to set. It will also cause a misfire
due to an inoperative injector. A misfire DTC should also
be set indicating which injector is inoperative.
Long–term and short–terms fuel trims that are excessively
high or low are a good indication that an injector is mal-
functioning. Refer to ”Fuel Injector Balance Test” in this
section to check for malfunctioning injectors.
The injector resistance tested at the ECM connection is
slightly more than it tested directly at the injector because
it includes resistance of the harness wires. The normal val-
ue is about 13.5W.

ENGINE CONTROLS 1F – 179
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P0267
INJECTOR 3 LOW VOLTAGE
Circuit Description
The transaxle control module(TCM)/engine control mod-
ule (ECM) has four individual injector driver circuits, each
of which controls an injector. When a driver circuit is
grounded by the ECM, the injector is activated. The ECM
monitors the current in each driver circuit. The ECM mea-
sures a voltage drop through a fixed resistor and controls
it. The voltage on each driver is monitored to detect a fault.
If the voltage is not what the ECM expects to monitor on
the circuit, a Diagnostic Trouble Code (DTC) is set. This
DTC detects a low voltage and/or an open circuit and high
voltage conditions for low–side drive injector outputs.
Conditions for Setting the DTC
S The injector 3 circuit is an open or a short to ground
condition exists.
Action Taken When the DTC Sets
S The Malfunction Indicator Lamp (MIL) will illumi-
nate.
S The ECM will record operating conditions at the
time the diagnostic fails. This information will be
stored in the Freeze Frame and Records buffers.S A history DTC is stored.
Conditions for Clearing the MIL/DTC
S The MIL will turn off after 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 10 sec-
onds.
Diagnostic Aids
An injector driver circuit that is open or shorted to voltage
will causes a DTC P0267 to set. It will also cause a misfire
due to an inoperative injector. A misfire DTC should also
be set indicating which injector is inoperative.
Long–term and short–terms fuel trims that are excessively
high or low are a good indication that an injector is mal-
functioning. Refer to ”Fuel Injector Balance Test” in this
section to check for malfunctioning injectors.
The injector resistance tested at the ECM connection is
slightly more than it tested directly at the injector because
it includes resistance of the harness wires. The normal val-
ue is about 13.5W.

ENGINE CONTROLS 1F – 181
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P0268
INJECTOR 3 HIGH VOLTAGE
Circuit Description
The transaxle control module(TCM)/engine control mod-
ule (ECM) has four individual injector driver circuits, each
of which controls an injector. When a driver circuit is
grounded by the ECM, the injector is activated. The ECM
monitors the current in each driver circuit. The ECM mea-
sures a voltage drop through a fixed resistor and controls
it. The voltage on each driver is monitored to detect a fault.
If the voltage is not what the ECM expects to monitor on
the circuit, a Diagnostic Trouble Code (DTC) is set. This
DTC detects a low voltage and/or an open circuit and high
voltage conditions for low–side drive injector outputs.
Conditions for Setting the DTC
S The injector 3 circuit is a short to battery condition
exists.
Action Taken When the DTC Sets
S The Malfunction Indicator Lamp (MIL) will illumi-
nate.
S The ECM will record operating conditions at the
time the diagnostic fails. This information will be
stored in the Freeze Frame and Records buffers.S A history DTC is stored.
Conditions for Clearing the MIL/DTC
S The MIL will turn off after 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 10 sec-
onds.
Diagnostic Aids
An injector driver circuit that is open or shorted to voltage
will causes a DTC P0268 to set. It will also cause a misfire
due to an inoperative injector. A misfire DTC should also
be set indicating which injector is inoperative.
Long–term and short–terms fuel trims that are excessively
high or low are a good indication that an injector is mal-
functioning. Refer to ”Fuel Injector Balance Test” in this
section to check for malfunctioning injectors.
The injector resistance tested at the ECM connection is
slightly more than it tested directly at the injector because
it includes resistance of the harness wires. The normal val-
ue is about 13.5W.

ENGINE CONTROLS 1F – 183
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P0270
INJECTOR 4 LOW VOLTAGE
Circuit Description
The transaxle control module(TCM)/engine control mod-
ule (ECM) has four individual injector driver circuits, each
of which controls an injector. When a driver circuit is
grounded by the ECM, the injector is activated. The ECM
monitors the current in each driver circuit. The ECM mea-
sures a voltage drop through a fixed resistor and controls
it. The voltage on each driver is monitored to detect a fault.
If the voltage is not what the ECM expects to monitor on
the circuit, a Diagnostic Trouble Code (DTC) is set. This
DTC detects a low voltage and/or an open circuit and high
voltage conditions for low–side drive injector outputs.
Conditions for Setting the DTC
S The injector 4 circuit is an open or a short to ground
condition exists.
Action Taken When the DTC Sets
S The Malfunction Indicator Lamp (MIL) will illumi-
nate.
S The ECM will record operating conditions at the
time the diagnostic fails. This information will be
stored in the Freeze Frame and Records buffers.S A history DTC is stored.
Conditions for Clearing the MIL/DTC
S The MIL will turn off after 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 10 sec-
onds.
Diagnostic Aids
An injector driver circuit that is open or shorted to voltage
will causes a DTC P0270 to set. It will also cause a misfire
due to an inoperative injector. A misfire DTC should also
be set indicating which injector is inoperative.
Long–term and short–terms fuel trims that are excessively
high or low are a good indication that an injector is mal-
functioning. Refer to ”Fuel Injector Balance Test” in this
section to check for malfunctioning injectors.
The injector resistance tested at the ECM connection is
slightly more than it tested directly at the injector because
it includes resistance of the harness wires. The normal val-
ue is about 13.5W.