Lamp DAEWOO LACETTI 2004 Service Owner's Guide

1F – 34IENGINE CONTROLS
DAEWOO V–121 BL4
ON–BOARD DIAGNOSTIC (EOBD) SYSTEM CHECK
(1.8L DOHC)
Circuit Description
The On–Board Diagnostic (EOBD) system check is the
starting point for any driveability complaint diagnosis. Be-
fore using this procedure, perform a careful visual/physi-
cal check of the engine control module (ECM) and the en-
gine grounds for cleanliness and tightness.
The EOBD system check is an organized approach to
identifying a problem created by an electronic engine con-
trol system malfunction.
Diagnostic Aids
An intermittent may be caused by a poor connection,
rubbed–through wire insulation or a wire broken inside the
insulation. Check for poor connections or a damaged har-
ness. Inspect the ECM harness and connections for im-
proper mating, broken locks, improperly formed or dam-
aged terminals, poor terminal–to–wire connection, and
damaged harness.Test Description
Numbers below refer to the step number on the Diagnostic
Chart:
1. The Malfunction Indicator Lamp (MIL) should be
ON steady with the ignition ON and the engine
OFF. If not, go to”Diagnostic Aids”.
2. Checks the Class 2 data circuit and ensures that
the ECM is able to transmit serial data.
3. This test ensures that the ECM is capable of con-
trolling the MIL and the MIL driver circuit is not
shorted to ground.
4. If the engine will not start, refer to ”Engine Cranks
But Will Not Run” in this section.
7. A scan tool parameter which is not within the typical
range may help to isolate the area which is causing
the problem.
10. This vehicle is equipped with a ECM which utilizes
an Electrically Erasable Programmable Read Only
Memory (EEPROM). The replacement ECM must
be programmed. Refer to the latest Techline proce-
dure for ECM reprogramming.

ENGINE CONTROLS 1F – 35
DAEWOO V–121 BL4
On–Board Diagnostic (EOBD) System Check (1.8L DOHC)
StepActionValue(s)YesNo
11. Turn the ignition switch to ON.
2. Observe the Malfunction Indicator Lamp (MIL).
Is the MIL illuminate?–Go to Step 2Go to
”No Malfunction
Indicator Lamp”
21. Turn the ignition switch to LOCK.
2. Install the scan tool to the Data link Connector
(DLC).
3. Turn the ignition switch to ON.
4. Attempt to display the Engine Control Module
(ECM) engine data with the scan tool.
Does the scan tool display the ECM engine data?–Go to Step 3Go to Step 8
31. Using the scan tool output test function, select
the MIL lamp control and command the MIL off.
2. Observe the MIL.
Does the MIL turn OFF?–Go to Step 4Go to
”Malfunction In-
dicator Lamp
on Steady”
4Attempt to start the engine.
Does the engine start and continue to run?–Go to Step 5Go to
”Engine Cranks
But Will Not
Run”
5Select DISPLAY DTC with the scan tool.
Are any Diagnostic Trouble Codes (DTCs) stored?–Go to Step 6Go to Step 7
6Check the display for DTCs P0107, P0108, P0113,
P0118, P0122, P0123, P0712, P1392.
Are two or more of the following DTCs stored?–Go to
”Multiple ECM
Information
Sensor DTCs
Set”Go to applica-
ble DTC table
7Compare the ECM data values displayed on the
scan tool to the typical engine scan data values.
Are the displayed values normal or close to the typi-
cal values?–Go to
”ECM Output
Diagnosis”Go to indicated
component
system check
81. Turn the ignition switch to LOCK.
2. Disconnect the ECM connector.
3. Turn the ignition switch to ON.
4. Check the serial data circuit for an open, short
to ground, or short to voltage. Also check the
DLC ignition feed circuit for an open or short to
ground, and check the DLC ground circuits for
an open.
Is a problem found?–Go to Step 9Go to Step 10
9Repair the open, short to ground, or short to voltage
in the serial data circuit or the DLC ignition feed cir-
cuit.
Is the repair complete?–System OK–
101. Attempt to reprogram the ECM.
2. Attempt to display the ECM data with the scan
tool.
Does the scan tool display ECM engine data?–Go to Step 2Go to Step 11
11Replace the ECM.
Is the replacement complete?–System OK–

1F – 54IENGINE CONTROLS
DAEWOO V–121 BL4
NO MALFUNCTION INDICATOR LAMP (1.4L/1.6L DOHC)
Circuit Description
When the ignition is turned ON, the Malfunction Indicator
Lamp (MIL) will be turned ON and remain ON until the en-
gine is running, if no Diagnostic Trouble Codes (DTCs) are
stored. Battery voltage is supplied through the ignition
switch directly to the MIL telltale. The Engine Control Mod-
ule (ECM) controls the MIL by providing a ground path
through the MIL control circuit to turn ON the MIL.
Diagnostic Aids
An open ignition fuse F4 will cause the entire cluster to beinoperative.
Check the battery and ignition feed circuits for poor con-
nections if the MIL is intermittent.
Any circuitry, that is suspected as causing an intermittent
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.

ENGINE CONTROLS 1F – 55
DAEWOO V–121 BL4
No Malfunction Indicator Lamp (1.4L/1.6L DOHC)
StepActionValue(s)YesNo
1Attempt to start the engine.
Does the engine start?–Go to Step 2Go to
”Engine Cranks
But Will Not
Run”
21. Turn the ignition switch to LOCK.
2. Disconnect the Engine Control Module (ECM)
connector.
3. Turn the ignition switch to ON.
4. Connect a test light between the ECM connec-
tor terminal 39 and ground.
Is the test light illuminate?–Go to Step 3Go to Step 6
3Check terminals for damage or poor connection.
Does any problem found?–Go to Step 5Go to Step 4
4Replace the ECM.
Is the replacement complete?–Go to
”On–Board
Diagnostic Sys-
tem Check”–
5Repair any damaged terminals or poor connection.
Is the repair complete?–Go to
”On–Board
Diagnostic Sys-
tem Check”–
6Check the fuse F4.
Is the fuse open?Go to Step 7Go to Step 8
71. Check for a short to ground in the circuit and
repair as needed.
2. Replace the fuse F4.
Is the repair or replacement complete?–Go to
”On–Board
Diagnostic Sys-
tem Check”–
81. Check for an open circuit between fuse F4 and
the ECM connector terminal 39 and repair as
needed.
2. Check the MIL bulb and replace if open.
Is the repair or replacement complete?–Go to
”On–Board
Diagnostic Sys-
tem Check”–

1F – 56IENGINE CONTROLS
DAEWOO V–121 BL4
NO MALFUNCTION INDICATOR LAMP (1.8L DOHC)
Circuit Description
When the ignition is turned ON, the Malfunction Indicator
Lamp (MIL) will be turned ON and remain ON until the en-
gine is running, if no Diagnostic Trouble Codes (DTCs) are
stored. Battery voltage is supplied through the ignition
switch directly to the MIL telltale. The Engine Control Mod-
ule (ECM) controls the MIL by providing a ground path
through the MIL control circuit to turn ON the MIL.
Diagnostic Aids
An open ignition fuse F4 will cause the entire cluster to be
inoperative.
Check the battery and ignition feed circuits for poor con-
nections if the MIL is intermittent.Any circuitry, that is suspected as causing an intermittent
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.
Test Description
Number(s) below refer to the step(s) on the diagnostic
table.
1. If the engine fails to start and the MIL is inopera-
tive, then the fault can be isolated to either the
ECM ignition feed. The battery feed, or a poor
ground at the engine block, or the ECM.
2. Probing the MIL circuit with a test light to ground
stimulates the ECM’s control of the MIL. If the MIL
illuminates, then the malfunction can be isolated to
the control of the MIL or a poor connection at the
MIL terminal to the ECM.

ENGINE CONTROLS 1F – 57
DAEWOO V–121 BL4
No Malfunction Indicator Lamp (1.8L DOHC)
StepActionValue(s)YesNo
1Attempt to start the engine.
Does the engine start?–Go to Step 2Go to
”Engine Cranks
But Will Not
Run”
21. Turn the ignition switch to LOCK.
2. Disconnect the Engine Control Module (ECM)
connector.
3. Turn the ignition switch to ON.
4. Connect a test light between the ECM connec-
tor terminal K64 and ground.
Is the test light illuminate?–Go to Step 3Go to Step 6
3Check terminals for damage or poor connection.
Does any problem found?–Go to Step 5Go to Step 4
4Replace the ECM.
Is the replacement complete?–Go to
”On Board
Diagnostic Sys-
tem Check”–
5Repair any damaged terminals or poor connection.
Is the repair complete?–Go to
”On Board
Diagnostic Sys-
tem Check”–
6Check the fuse F4.
Is the fuse open?Go to Step 7Go to Step 8
71. Check for a short to ground in the circuit and
repair as needed.
2. Replace the fuse F4.
Is the repair or replacement complete?–Go to
”On Board
Diagnostic Sys-
tem Check”
81. Check for an open circuit between fuse F4 and
the ECM connector terminal K64 and repair as
needed.
2. Check the MIL bulb and replace if open.
Is the repair or replacement complete?–Go to
”On Board
Diagnostic Sys-
tem Check”–

1F – 58IENGINE CONTROLS
DAEWOO V–121 BL4
MALFUNCTION INDICATOR LAMP ON STEADY
(1.4L/1.6L DOHC)
Circuit Description
When the ignition switch is turned ON, the Malfunction In-
dicator Lamp (MIL) will be turned ON and remain ON until
the engine is running, if no Diagnostic Trouble Codes
(DTCs) are stored. Battery voltage is supplied through the
ignition switch directly to the MIL telltale. The Engine Con-
trol Module (ECM) controls the MIL by providing a ground
path through the MIL control circuit to turn ON the MIL.
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 stored
in the scan tool for later reference.
2. When the ignition is turned ON, the MIL should be
turned on and remain on until the engine is running
or if an emission related DTC is stored. This step
checks the ability of the ECM to control the MIL.
The scan tool has the ability to command the MIL
on and off.
4. A shorted MIL circuit can be diagnosed with a scan
tool.
6. The replacement ECM must be reprogrammed.
Refer to the latest Techline information for repro-
gramming procedures.

ENGINE CONTROLS 1F – 59
DAEWOO V–121 BL4
Malfunction Indicator Lamp On Steady (1.4L/1.6L DOHC)
StepActionValue(s)YesNo
1Perform an On–Board Diagnostic (EOBD) system
check.
Is the check complete.–Go to Step 2Go to
”On–Board
Diagnostic Sys-
tem Check”
21. Turn the ignition switch to LOCK.
2. Install the scan tool to the Data Link Connector
(DLC).
3. Command the Malfunction Indicator Lamp
(MIL) ON and OFF.
Does the MIL turn ON and OFF when commanded?–Go to Step 7Go to Step 3
31. Turn the ignition switch to LOCK.
2. Disconnect the Engine Control Module (ECM)
connector.
3. Turn the ignition switch to ON.
Is the MIL off?–Go to Step 6Go to Step 4
4Check the MIL control circuit for a short to ground
and repair as needed.
Is the repair complete?–Go to Step 7Go to Step 5
5Replace the instrument panel cluster. Refer to Sec-
tion 9E, Instrumentation/Driver Information.
Is the repair complete?–Go to Step 7–
6Replace the ECM.
Is the repair complete?–Go to Step 7–
71. Using the scan tool, clear the Diagnostic
Trouble Codes(DTCs).
2. Attempt to start the engine.
Does the engine start and continue to run?–Go to Step 8Go to Step 1
81. Allow the engine to idle until normal operating
temperature is reached.
2. Check if any DTCs are set.
Are any DTCs displayed that have not been diag-
nosed?–Go to
Applicable DTC
tableSystem OK

1F – 60IENGINE CONTROLS
DAEWOO V–121 BL4
MALFUNCTION INDICATOR LAMP ON STEADY
(1.8L DOHC)
Circuit Description
When the ignition switch is turned ON, the Malfunction In-
dicator Lamp (MIL) will be turned ON and remain ON until
the engine is running, if no Diagnostic Trouble Codes
(DTCs) are stored. Battery voltage is supplied through the
ignition switch directly to the MIL telltale. The Engine Con-
trol Module (ECM) controls the MIL by providing a ground
path through the MIL control circuit to turn ON the MIL.
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 stored
in the scan tool for later reference.
2. When the ignition is turned ON, the MIL should be
turned on and remain on until the engine is running
or if an emission related DTC is stored. This step
checks the ability of the ECM to control the MIL.
The scan tool has the ability to command the MIL
on and off.
4. A shorted MIL circuit can be diagnosed with a scan
tool.
6. The replacement ECM must be reprogrammed.
Refer to the latest Techline information for repro-
gramming procedures.

ENGINE CONTROLS 1F – 61
DAEWOO V–121 BL4
Malfunction Indicator Lamp On Steady (1.8L DOHC)
StepActionValue(s)YesNo
1Perform an On–Board Diagnostic (EOBD) system
check.
Is the check complete.–Go to Step 2Go to
”On–Board
Diagnostic Sys-
tem Check”
21. Turn the ignition switch to LOCK.
2. Install the scan tool to the Data Link Connector
(DLC).
3. Command the Malfunction Indicator Lamp
(MIL) ON and OFF.
Does the MIL turn ON and OFF when commanded?–Go to Step 7Go to Step 3
31. Turn the ignition switch to LOCK.
2. Disconnect the Engine Control Module (ECM)
connector.
3. Turn the ignition switch to ON.
Is the MIL off?–Go to Step 6Go to Step 4
4Check the MIL control circuit for a short to ground
and repair as needed.
Is the repair complete?–Go to Step 7Go to Step 5
5Replace the instrument panel cluster. Refer to
Section 9E, Instrumentation/Driver Information.
Is the repair complete?–Go to Step 7–
6Replace the ECM.
Is the repair complete?–Go to Step 7–
71. Using the scan tool, clear the Diagnostic
Trouble Codes(DTCs).
2. Attempt to start the engine.
Does the engine start and continue to run?–Go to Step 8Go to Step 1
81. Allow the engine to idle until normal operating
temperature is reached.
2. Check if any DTCs are set.
Are any DTCs displayed that have not been diag-
nosed?–Go to
” Applicable
DTC table”System OK