2004 DAEWOO LACETTI check engine light

ENGINE CONTROLS 1F – 503
DAEWOO V–121 BL4
StepNo Yes Value(s) Action
51. Turn the ignition OFF.
2. Disconnect the IAC valve connector.
3. Turn the ignition ON.
4. With test light connected to ground, probe the
IAC connector terminals.
Does the test light illuminate on 2 terminals?–Go to Step 6Go to Step 7
6With test light connected to B+, probe the IAC con-
nector terminals.
Does the test light illuminate on 2 terminals?–Go to Step 8Go to Step 9
7Check for an open or short to ground in the IAC high
and low circuits and repair as needed.
Is the repair complete?–Go to Step 15Go to Step 10
81. Idle the engine.
2. Connect a test light to ground, probe the IAC
connector terminals.
Does the test light flash On and OFF for all termi-
nals?–Go to Step 11Go to Step 12
9Check for an open or a short to voltage in the IAC
valve high and low circuits and repair as needed.
Is the repair complete?–Go to Step 15Go to Step 10
10Check the Engine control Module (ECM) connector
for poor connections and repair as needed.
Is the repair necessary?–Go to Step 15Go to Step 14
11Inspect the IAC valve passages and repair as need-
ed.
Is the problem found?–Go to Step 15Go to Step 13
12Check the test light.
Does the test light remain on constantly for the termi-
nals that did not blink?–Go to Step 9Go to Step 7
131. Turn the ignition OFF.
2. Replace the IAC valve.
Is the repair complete?–Go to Step 15–
141. Turn the ignition OFF.
2. Replace the ECM.
Is the repair complete?–Go to Step 15–
151. 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 16Go to Step 2
16Check 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 – 505
DAEWOO V–121 BL4
S Fuel system too rich or too lean.
S Foreign material in the throttle body bore or in the
air induction system.
S A leaking or restricted intake manifold.
S Excessive engine overloading. Check for seized
pulleys, pumps, or motors on the accessory drive.
S Overweight engine oil.
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. A normally operating IAC system will be able to be
extended and retracted by a scan tool and change
the engine idle rpm. Valve movement is verified by
an engine rpm change.
3. If the scan tool was able to command the IAC valve
smoothly, a malfunction may still exist internally
within the IAC valve. This can be checked by
checking the IAC valves internal resistance.5. The IAC circuits always have ground or voltage sig-
nals on them in pairs. If the test light illuminates on
more or less than 2 terminals, 1 of the circuits is
shorted to voltage or open.
6. The IAC circuits always have ground or voltage sig-
nals on them in pairs. If the test light illuminates on
more or less than 2 terminals, 1 of the circuits is
shorted to ground or open
8. The IAC circuits are constantly switched between
ground and voltage so the test light should blink on
all circuits when connected to ground.
10. Any circuitry, that is suspected as causing the inter-
mittent complaint, should be thoroughly checked for
backed–out terminals, improper mating, broken
locks, improperly formed or damaged terminals,
poor terminal– to–wiring connections or physical
damage to the wiring harness.
12. A test light that remains ON constantly indicates
that the circuit is shorted to voltage.
14. The replacement ECM must be reprogrammed.
Refer to the latest Techline procedure for ECM re-
programming.
16. 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 for additional checks and information.
DTC P0507 – Idle Speed RPM Higher Than Desired Idle Speed
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. Operate the engine to idle speed.
3. Transmission in park or neutral and the parking
brake set.
4. A/C is Off.
5. Using scan tool, command the Idle Air Control
(IAC) valve up and down between the specified
value.
Does the rpm change smoothly when he command-
ed by the scan tool?900–1200 rpmGo to Step 3Go to Step 5
31. Turn the ignition OFF.
2. Disconnect the IAC valve connector.
3. Measure the resistance between terminal D
and C of the IAC valve.
4. Measure the resistance between terminal B
and A of the IAC valve.
Is the resistance within the specified value?40–80 WGo to Step 4Go to Step 13
41. Measure the resistance between terminal C
and B of the IAC valve.
2. Measure the resistance between terminal D
and A of the IAC valve.
Is the resistance equal to the specified value?–Go to Step 15Go to Step 13

1F – 506IENGINE CONTROLS
DAEWOO V–121 BL4
StepNo Yes Value(s) Action
51. Turn the ignition OFF.
2. Disconnect the IAC valve connector.
3. Turn the ignition ON.
4. With test light connected to ground, probe the
IAC connector terminals.
Does the test light illuminate on 2 terminals?–Go to Step 6Go to Step 7
6With test light connected to B+, probe the IAC con-
nector terminals.
Does the test light illuminate on 2 terminals?–Go to Step 8Go to Step 9
7Check for an open or short to ground in the IAC high
and low circuits and repair as needed.
Is the repair complete?–Go to Step 15Go to Step 10
81. Idle the engine.
2. Connect a test light to ground, probe the IAC
connector terminals.
Does the test light flash On and OFF for all termi-
nals?–Go to Step 11Go to Step 12
9Check for an open or a short to voltage in the IAC
valve high and low circuits and repair as needed.
Is the repair complete?–Go to Step 15Go to Step 10
10Check the Engine control Module (ECM) connector
for poor connections and repair as needed.
Is the repair necessary?–Go to Step 15Go to Step 14
11Inspect the IAC valve passages and repair as need-
ed.
Is the repair complete?–Go to Step 15Go to Step 13
12Check the test light.
Does the test light remain on constantly for the termi-
nals that did not blink?–Go to Step 9Go to Step 7
131. Turn the ignition OFF.
2. Replace the IAC valve.
Is the repair complete?–Go to Step 15–
141. Turn the ignition OFF.
2. Replace the ECM.
Is the repair complete?–Go to Step 15–
151. 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 16Go to Step 2
16Check if any additional DTCs are set.
Are any DTCs displayed that have not been diag-
nosed?–Go to
Applicable DTC
tableSystem OK

1F – 508IENGINE CONTROLS
DAEWOO V–121 BL4
DTC P0532 – A/C Pressure Sensor 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. Idle the engine.
Does the scan tool display Air Conditioning Pressure
(ACP) sensor voltage below the specified value?0.06 VGo to Step 3Go to Step 4
31. Turn the ignition OFF.
2. Disconnect the ACP sensor connector.
3. Jumper the ACP signal circuit, terminal 2 to the
5 volt reference circuit, terminal 1.
4. Turn the ignition switch on.
Does the ACP voltage read more than the specified
value?4.9 VGo to Step 5Go to Step 6
41. Turn the ignition ON, with the engine OFF.
2. Operate the vehicle within the Failure Record
conditions and Conditions For Setting the DTC
as noted.
Does the scan tool display ACP voltage below the
specified value?0.06 VGo to Step 3Go to
”Diagnostic
Aids”
5Inspect the ACP sensor harness connector termi-
nals for the following conditions:
S Poor connections
S Proper contact tension
S Poor terminal–to–wire connection
Is a problem found?–Go to Step 8Go to Step 9
61. Turn the ignition OFF.
2. Remove the jumper wire.
3. Probe the ACP sensor signal circuit terminal 2
with a test light to B+.
4. Turn the ignition ON.
Does the scan tool read over the specified value?4 VGo to Step 7Go to Step 11
7Check the ACP sensor 5 volt reference circuit for an
open or short to ground and repair as needed.
Is the repair complete?–Go to Step 13Go to Step 10
8Repair the connection terminals as necessary.
Is the repair complete?–Go to Step 13–
91. Turn the ignition OFF.
2. Replace the ACP sensor.
Is the repair complete?–Go to Step 13–
101. Turn the ignition OFF.
2. Replace the engine control module (ECM).
Is the repair complete?–Go to Step 13–

ENGINE CONTROLS 1F – 511
DAEWOO V–121 BL4
DTC P0533 – A/C Pressure Sensor High 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. Idle the engine.
Does the scan tool display Air Conditioning Pressure
(ACP) sensor voltage below the specified value?0.06 VGo to Step 3Go to Step 4
31. Turn the ignition OFF.
2. Disconnect the ACP sensor connector.
3. Jumper the ACP signal circuit, terminal 2 to the
5 volt reference circuit, terminal 1.
4. Turn the ignition switch on.
Does the ACP voltage read more than the specified
value?4.9 VGo to Step 5Go to Step 6
41. Turn the ignition ON, with the engine OFF.
2. Operate the vehicle within the Failure Record
conditions and Conditions For Setting the DTC
as noted.
Does the scan tool display ACP voltage below the
specified value?0.06 VGo to Step 3Go to
”Diagnostic
Aids”
5Inspect the ACP sensor harness connector termi-
nals for the following conditions:
S Poor connections
S Proper contact tension
S Poor terminal–to–wire connection
Is a problem found?–Go to Step 8Go to Step 9
61. Turn the ignition OFF.
2. Remove the jumper wire.
3. Probe the ACP sensor signal circuit terminal 2
with a test light to B+.
4. Turn the ignition ON.
Does the scan tool read over the specified value?4 VGo to Step 7Go to Step 11
7Check the ACP sensor 5 volt reference circuit for an
open or short to ground and repair as needed.
Is the repair complete?–Go to Step 13Go to Step 10
8Repair the connection terminals as necessary.
Is the repair complete?–Go to Step 13–
91. Turn the ignition OFF.
2. Replace the ACP sensor.
Is the repair complete?–Go to Step 13–
101. Turn the ignition OFF.
2. Replace the engine control module (ECM).
Is the repair complete?–Go to Step 13–

ENGINE CONTROLS 1F – 559
DAEWOO V–121 BL4
DTC P1393 – G Sensor Rough Road High Voltage
StepActionValue(s)YesNo
1Perform an On–Board Diagnostic (EOBD) System
Check.
Is the system check complete?–Go to Step 2Go to
”On–Board
Diagnostic Sys-
tem Check”
21. Turn the ignition OFF.
2. Install a scan tool to the Data Link Connector
(DLC).
3. Start and idle the engine.
4. Observe the ROUGH ROAD value displayed
on the scan tool.
Is the ROUGH ROAD value near the specified val-
ue?4.5 vGo to Step 4Go to Step 3
31. Review and record the scan tool Failure Re-
cords data.
2. Operate the vehicle within Failure Records
conditions as noted.
3. Using the scan tool, monitor specific Diagnostic
Trouble Code (DTC) info for DTC P1393.
Does the scan tool indicate that DTC P1393 failed?–Go to Step 4Go to
”Diagnostic
Aids”
41. Turn the ignition OFF.
2. Disconnect the G sensor electrical connector.
3. Turn the ignition ON, with the engine OFF.
4. Note the G sensor voltage displayed on the
scan tool.
Is the G sensor value near the specified value?0 vGo to Step 5Go to Step 6
5Probe the sensor ground circuit terminal C with a test
light to B+.
Is the test light ON?–Go to Step 7Go to Step 9
6Check the G sensor signal circuit for a short to volt-
age or a short to the 5 volt reference circuit and re-
pair as needed.
Is the repair complete?–Go to Step 12Go to Step 11
7Check for a poor sensor ground terminal connection
at the G sensor electrical connector.
Is the repair complete?–Go to Step 12Go to Step 8
8Check for a poor sensor ground terminal connection
at the Engine Control Module (ECM) and repair as
needed.
Is the repair complete?–Go to Step 12Go to Step 10
9Check the G sensor ground circuit for an open and
repair as needed.
Is the repair complete?–Go to Step 12Go to Step 10
101. Turn the ignition OFF.
2. Replace the ECM.
Is the repair complete?–Go to Step 12–
11Replace the G sensor.
Is the repair complete?–Go to Step 12Go to Step 10

ENGINE CONTROLS 1F – 567
DAEWOO V–121 BL4
StepNo Yes Value(s) Action
7With a teat light connected to ground, probe the
EGR valve wiring harness connector terminal 1.
Does the test light illuminate?–Go to Step 9Go to Step 10
8Check the 5 volt reference circuit for a short to volt-
age and repair as needed.
Is a repair complete?–Go to Step 13Go to Step 6
9Check the control circuit for a short to voltage and re-
pair as needed.
Is the repair complete?–Go to Step 13Go to Step 6
10Check the EGR ground circuit for an open or poor
connection at the EGR valve harness connector and
repair as needed.
Is a repair necessary.–Go to Step 13Go to Step 12
111. Turn the ignition OFF.
2. Replace the EGR valve.
Is the repair complete?–Go to Step 13–
12Check the ECM connector for a poor connection and
repair as needed.
Is the repair complete?–Go to Step 13–
131. 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 ran
and passed?–Go to Step 14Go to Step 2
14Check 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 – 575
DAEWOO V–121 BL4
StepNo Yes Value(s) Action
5Replace the sensor in the affected circuit, if a Diag-
nostic Trouble Code (DTC) was stored for this circuit
(except for the DTCs P0171 and P0172.
Is the repair complete?–System OK–
6Does an intermittent Malfunction Indicator Lamp
(MIL) or DTC occur?–Go toStep 7Go toStep 8
71. Check for a faulty relay, electronic control mod-
ule (ECM) driven solenoid, or switch.
2. Check for improper installation of electrical de-
vices, such as lights, two–way radios, electric
motors, etc.
3. Inspect the ignition control wires for proper
routing (away from ignition wires, ignition sys-
tem components, and the generator).
4. Check for a short–to–ground in the MIL circuit
or the DLC ”test” terminal.
5. Inspect the ECM ground connections.
6. Correct or repair the affected circuits as need-
ed.
Is the repair complete?–System OK–
81. Check for a loss of DTC memory.
2. 2. Disconnect the Throttle Position Sensor.
3. Run the engine at idle until the MIL comes on.
4. Turn the ignition OFF.
Is DTC P0122 stored in memory?–Go toStep 10Go toStep 9
9Replace the ECM.
Is the repair complete?–System OK–
10Does the vehicle stall while driving?–Go toStep 11Go toStep 12
11Monitor the Front Heated Oxygen Sensor (HO2S1)
and the injector base pulse width with the scan tool.
Does the scan tool display a steady low voltage
(about 0 mv) for the HO2S1 sensor with the control
module commanding an injector base pulse width of
the value specified?8 msGo toStep 9Go toStep 12
121. Check for an open diode across the A/C clutch
and for other open diodes.
2. Repair or replace any components as needed.
Is the repair complete?–System OK–