display DAEWOO LACETTI 2004 Service Repair Manual

1F – 354IENGINE CONTROLS
DAEWOO V–121 BL4
StepNo Yes Value(s) Action
7With a ohmmeter connected to the ground, probe
the 5 volt reference circuit terminal M16.
Is the resistance within near the specified value.5 vGo to Step 8Go to Step 9
8Check the MAP sensor vacuum source for being
plugged or leaking.
Is a problem found?–Go to Step 10Go to Step 13
9Check the 5 volt reference circuit at terminal M16 for
a short to voltage and repair as needed.
Is the repair complete?–Go to Step 14Go to Step 12
10Repair the vacuum source as needed.
Is the action complete?–Go to Step 14–
11Check for an open in the MAP sensor ground circuit
at terminal 1 and repair as needed.
Is the repair complete?–Go to Step 14Go to Step 12
121. Turn the ignition switch OFF.
2. Replace the Engine Control Module (ECM).
Is the action complete?–Go to Step 14–
13Replace the MAP sensor.
Is the action complete?–Go to Step 14–
141. 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 15Go to Step 2
15Check if any additional DTCs are set.
Are any DTCs displayed that have not been diag-
nosed?–Go to
applicable DTC
tableSystem OK

ENGINE CONTROLS 1F – 355
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P0112
INTAKE AIR TEMPERATURE LOW VOLTAGE
Circuit Description
The Intake Air Temperature (IAT) sensor uses a thermistor
to control the signal voltage to the Engine Control Module
(ECM). The ECM supplies a 5 volt reference and a ground
to the sensor. When the air is cold, the resistance is high;
therefore the IAT signal voltage will be high. If the intake
air is warm, resistance is low; therefore the IAT signal volt-
age will be low.
Conditions for Setting the DTC
S IAT is less than 149°C (300°F).
S Engine run time is greater than 120 seconds.
S Vehicles speed is greater than or equal to 50 km/h
(31 mph).
S DTC P0502 is not set.
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 DTC is stored.
S The ECM will substitute a default value for intake
air temperature. The scan tool will not show the
defaulted value.
Conditions for Clearing the MIL/DTC
S The MIL will turn 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
If the vehicle is at ambient temperature, compare the IAT
sensor to the Engine Coolant Temperature (ECT) sensor.
The IAT sensor and the ECT sensor should be relatively
close to each other.
Use the Temperature vs. Resistance Values table to eval-
uate the possibility of a skewed sensor. Refer to ”Temper-
ature vs. Resistance” in this section.
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.
4. This step simulates a DTC P0113 condition. If the
scan tool displays the specified value, the IAT sig-
nal circuit, the ECM are OK.
8. The replacement ECM must be reprogrammed.
Refer to the latest Techline procedure for ECM re-
programming.

ENGINE CONTROLS 1F – 357
DAEWOO V–121 BL4
StepNo Yes Value(s) Action
101. 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 11Go to Step 2
11Check if any additional DTCs are set.
Are any DTCs displayed that have not been diag-
nosed?–Go to the appli-
cable DTC
tableSystem OK

1F – 360IENGINE CONTROLS
DAEWOO V–121 BL4
StepNo Yes Value(s) Action
121. 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 13Go to Step 2
13Check if any additional DTCs are set.
Are any DTCs displayed that have not been diag-
nosed?–Go to applica-
ble DTC tableSystem OK

1F – 362IENGINE CONTROLS
DAEWOO V–121 BL4
DTC P0117 – Engine Coolant Temperature Low Voltage
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.
Is the Engine Coolant Temperature (ECT) sensor
value greater than the specified value?130 °C
(266 °F)Go to Step 4Go to Step 3
31. Turn the ignition switch ON with the engine
OFF, review Freeze Frame data, and note the
parameters.
2. Operate the vehicle within the Freeze Frame
conditions and Conditions for Setting The DTC
as noted.
Is the ECT sensor value greater than the specified
value?130 °C
(266 °F)Go to Step 4Go to
”Diagnostic
Aids”
41. Turn the ignition switch OFF.
2. Disconnect the ECT sensor connector.
3. Turn the ignition switch ON.
Is the ECT sensor value below the specified value?–30 °C
(–22 °F)Go to Step 6Go to Step 5
5Check the ECT sensor signal circuit at terminal 1 for
a short to ground and repair as needed.
Is the repair complete?–Go to Step 8Go to Step 7
6Replace ECT sensor.
Is the repair complete?–Go to Step 8–
71. Turn the ignition OFF.
2. Replace the Engine Control Module (ECM).
Is the action complete?–Go to Step 8–
81. 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 9Go to Step 2
9Check if any additional DTCs are set.
Are any DTCs displayed that have not been diag-
nosed?–Go to applica-
ble DTC tableSystem OK

ENGINE CONTROLS 1F – 365
DAEWOO V–121 BL4
StepNo Yes Value(s) Action
121. Using the scan tool, clear the Diagnostic
Trouble Codes(DTVCs.)
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 scantool indicate that this diagnostic has
run and passed?–Go to Step 13Go to Step 2
13Check if any additional DTCs are set.
Are any DTCs displayed that have not been diag-
nosed?Go to applica-
ble DTC tableSystem OK

1F – 366IENGINE CONTROLS
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P0122
THROTTLE POSITION SENSOR LOW VOLTAGE
Circuit Description
The Engine Control Module (ECM) supplies a 5 volt refer-
ence voltage signal and a ground to the Throttle Position
(TP) sensor. The TP sensor sends a voltage signal back
to the ECM relative to the throttle plate opening. The volt-
age signal will vary from approximately 0.33 volts at closed
throttle, to over 4.3 volts at Wide Open Throttle (WOT).
The TP signal is used by the ECM for fuel control and for
most of the ECM controlled outputs. The TP signal is one
of the most important inputs used by the ECM for fuel con-
trol and most of the ECM controlled outputs.
Conditions for Setting the DTC
S TP sensor voltage indicates a throttle voltage less
than 0.14 volts.
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 Failure Records
buffers.
S A history DTC is stored.
S The TP angle will default to 0% when the vehicle
speed is less than 3 km/h (2 mph) and 10% when
the vehicle speed is greater than 3 km/h (2 mph).
The scan tool will not display the default value.
Conditions for Clearing the MIL/DTC
S The MIL will turn 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
If the DTC P0122 cannot be duplicated, the information in-
cluded in the Freeze Frame data can be useful. Use a scan
tool information data to determine the status of the DTC.
If the dc occurs intermittently, using the Diagnostic table
may help isolate the problem.
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. The TP sensor has an auto zeroing feature. If the
voltage reading is between 0.2 to 0.9 volts, the
ECM will assume the TP sensor is at a closed
throttle position (0%).
5. Simulates a high voltage signal which will identify
an open in the signal circuit.
6. If additional DTCs are set, check the 5v reference
circuits for a short to ground.
8. If the test light illuminates while probing the TP sig-
nal circuit, then the TP signal circuit is shorted to
ground.
11. The replacement ECM must be reprogrammed.
Refer to the latest Techline procedure for ECM re-
programming.

1F – 368IENGINE CONTROLS
DAEWOO V–121 BL4
StepNo Yes Value(s) Action
121. 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 13Go to Step 2
13Check if any additional DTCs are set.
Are any DTCs displayed that have not been diag-
nosed?–Go to applica-
ble DTC tableSystem OK

ENGINE CONTROLS 1F – 369
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P0123
THROTTLE POSITION SENSOR HIGH VOLTAGE
Circuit Description
The Engine Control Module (ECM) supplies a 5 volt refer-
ence voltage signal and a ground to the Throttle Position
(TP) sensor. The TP sensor sends a voltage signal back
to the ECM relative to the throttle plate opening. The volt-
age signal will vary from approximately 0.33 volts at closed
throttle, to over 4.3 volts at Wide Open Throttle (WOT).
The TP signal is used by the ECM for fuel control and for
most of the ECM controlled outputs. The TP signal is one
of the most important inputs used by the ECM for fuel con-
trol and most of the ECM controlled outputs.
Conditions for Setting the DTC
S TP sensor voltage indicates a throttle voltage great-
er than 4.9 volts.
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 Failure Records
buffers.
S A history DTC is stored.
S The TP angle will default to 0% when the vehicle
speed is less than 3 km/h (2 mph) and 10% when
the vehicle speed is greater than 3 km/h (2 mph).
The scan tool will not display the default value.
Conditions for Clearing the MIL/DTC
S The MIL will turn 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
If the DTC P0123 cannot be duplicated, the information in-
cluded in the Freeze Frame data can be useful. Use a scan
tool information data to determine the status of the DTC.
If the dc occurs intermittently, using the Diagnostic table
may help isolate the problem.
With ignition ON and the throttle at closed position, the
voltage should read between 0.2 and 0.90 volts and in-
crease steadily to over 4.3 volts at WOT.
DTCs P0123 and P0113 stored at the same time could be
result of an open sensor ground circuit.
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. With the throttle closed, the TP sensor voltage
should read less than 0.90 volts. If the TP sensor
voltage does not read less than 0.90 volts check for
a binding or sticking throttle cable.
4. With the TP sensor disconnected, the TP sensor
voltage should be less than 0.2 volts if the ECM
and wiring are OK.
5. Probing the ground circuit with a test light checks
the circuit for high resistance which will cause a
DTC P0123 to set.

ENGINE CONTROLS 1F – 371
DAEWOO V–121 BL4
StepNo Yes Value(s) Action
121. 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 13Go to Step 2
13Check if any additional DTCs are set.
Are any DTCs displayed that have not been diag-
nosed?–Go to applica-
ble DTC tableSystem OK