check engine DAEWOO NUBIRA 2004 Service Manual Online

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

1F – 62IENGINE CONTROLS
DAEWOO V–121 BL4
FUEL SYSTEM DIAGNOSIS
Circuit Description
The fuel pump is an in–tank type mounted to a fuel sender
assembly. The fuel pump will remain on as long as the en-
gine is cranking or running and the Engine Control Module
(ECM) is receiving reference pulses from the crankshaft
position (CKP) sensor. If there are no reference pulses,
the ECM will turn off the fuel pump two seconds after the
ignition switch is turned ON or two seconds after the en-
gine stops running. The fuel pump delivers fuel to the fuel
rail and the fuel injectors, where the fuel system pressure
is controlled from 284 to 325 kPa (41 to 47 psi) by the fuel
pressure regulator. The excess fuel is returned to the fuel
tank.
Test Description
The number(s) below refer to step(s) on the diagnostic
table.
2. When the engine is idling, the intake manifold vacu-
um is high. This vacuum is applied to the fuel pres-
sure regulator diaphragm, offsetting the spring
pressure inside the fuel pressure regulator and low-
ering the fuel pressure.10. If there is fuel bleeding back through the fuel return
outlet, this is due to a faulty fuel pressure regulator.
14. Another symptom often present when the fuel injec-
tors are leaking is hard starting. Leaking fuel injec-
tors can cause a flooding condition.
23. Fuel leaking from the fuel pump inlet is due to a
faulty one–way check valve in the fuel pump.
CAUTION : The fuel system is under pressure. To
avoid fuel spillage and the risk of personal injury or
fire, it is necessary to relieve the fuel system pressure
before disconnecting the fuel lines.
CAUTION : Do not pinch or restrict nylon fuel lines to
avoid damage that could cause a fuel leak, resulting
in possible fire or personal injury.
Fuel Pressure Relief Procedure
1. Remove the fuel cap.
2. Remove the fuel pump fuse EF18 from the engine
fuse box.
3. Start the engine and allow the engine to stall.
4. Crank the engine for an additional 10 seconds.
Fuel System Diagnosis
StepActionValue(s)YesNo
11. Relieve the fuel system pressure.
2. Install a fuel pressure gauge.
3. Turn the ignition ON.
Is the fuel pressure within the values specified and
holding steady?284~325 kPa
(41~47psi)Go to Step 2Go to Step 4
21. Allow the engine to idle.
2. Disconnect the vacuum hose from the fuel
pressure regulator.
3. Connect a vacuum pump with a gauge to the
fuel pressure regulator vacuum port.
4. Apply 41~47 kPa (12~14 in. Hg) of vacuum to
the fuel pressure regulator.
Does the fuel pressure decrease?–Go to Step 3Go to Step 15
31. Locate and correct the cause of the vacuum
restriction to the fuel pressure regulator.
2. Confirm the operation of the fuel pressure reg-
ulator.
Is the repair complete?–System OK–
41. Relieve the fuel system pressure.
2. Install a fuel pressure gauge.
3. Turn the ignition ON.
Is the fuel pressure within the values specified but
not holding steady?284~325 kPa
(41~47psi)Go to Step 5Go to Step 16
5Inspect the fuel lines for a leak.
Is the problem found?–Go to Step 6Go to Step 7

ENGINE CONTROLS 1F – 65
DAEWOO V–121 BL4
FUEL PUMP RELAY CIRCUIT CHECK (1.4L/1.6L DOHC)
Circuit Description
When the ignition switch is turned ON, the Engine Control
Module (ECM) will supply battery voltage to activate the
fuel pump relay and run the in–tank fuel pump. The fuel
pump will operate as long as the engine is cranking or run-
ning and the ECM is receiving ignition reference pulses.
If there are no reference pulses, the ECM will shut off the
fuel pump within 2 seconds after the ignition switch is
turned ON.
Diagnostic Aids
An intermittent problem may be caused by a poor connec-
tion, rubbed through wire insulation, or a broken wire in-
side the insulation.Test Description
The number(s) below refer to step(s) on the diagnostic
table.
3. This step checks for the ECM providing a ground
for the operation of the fuel pump relay.
7. By confirming that the wiring is OK using Steps 2
through 6, it can be determined that the fuel pump
relay is at fault.
9. After determining that there is no ground being pro-
vided by the ECM to the fuel pump relay, the fault is
either the ECM or the wiring between the ECM and
the fuel pump relay.

1F – 66IENGINE CONTROLS
DAEWOO V–121 BL4
Fuel Pump Relay Circuit Check (1.4L/1.6L DOHC)
StepActionValue(s)YesNo
11. Turn the ignition OFF for 10 seconds.
2. Turn the ignition ON.
3. Listen for in–tank fuel pump operation.
Does the fuel pump operate for the time specified?2 secSystem OKGo to Step 2
21. Turn the ignition OFF.
2. Disconnect the fuel pump relay.
3. Connect a test light between the fuel pump
relay connector terminal 30 and ground.
Turn the ignition ON. Is the test light on?–Go to Step 3Go to Step 8
31. Turn the ignition OFF.
2. Connect a test light between the fuel pump
relay connector terminal 86 and battery posi-
tive.
3. Turn the ignition ON.
4. With the ignition ON, the test light should light
for the time specified.
Is the test light on?2 secGo to Step 4Go to Step 9
41. Turn the ignition OFF.
2. Connect a test light between the fuel pump
relay connector terminal 30 and ground.
Is the test light on?–Go to Step 5Go to Step 11
5Check for an open or short to ground in the wire be-
tween the fuel pump relay connector terminal 87 and
the fuel pump connector terminal 3.
Is the problem found?–Go to Step 6Go to Step 7
61. Repair the wire between the fuel pump relay
connector terminal 87 and the fuel pump con-
nector terminal 3.
2. Install the fuel pump relay.
3. Turn the ignition OFF for 10 seconds.
4. Turn the ignition ON.
Does the fuel pump operate for the time specified?2 secSystem OK–
71. Replace the fuel pump relay.
2. Turn the ignition OFF for 10 seconds.
3. Turn the ignition ON.
Does the fuel pump operate for the time specified?2 secSystem OK–
8Check for an open wire between the fuel pump relay
connector terminal 30 and the battery.
Is the problem found?–Go to Step 13–
9Check for an open wire between the fuel pump relay
connector terminal 86 to the engine control module
(ECM) connector terminal 6.
Is the problem found.–Go to Step 10Go to Step 12
101. Repair the wire between the fuel pump relay
connector terminal 86 to the ECM connector
terminal 6.
2. Install the fuel pump relay.
3. Turn the ignition OFF for 10 seconds.
4. Turn the ignition ON.
Does the fuel pump operate for the time specified?2 secSystem OK–

1F – 68IENGINE CONTROLS
DAEWOO V–121 BL4
FUEL PUMP RELAY CIRCUIT CHECK (1.8L DOHC)
Circuit Description
When the ignition switch is turned ON, the Engine Control
Module (ECM) will supply battery voltage to activate the
fuel pump relay and run the in–tank fuel pump. The fuel
pump will operate as long as the engine is cranking or run-
ning and the ECM is receiving ignition reference pulses.
If there are no reference pulses, the ECM will shut off the
fuel pump within 2 seconds after the ignition switch is
turned ON.
Diagnostic Aids
An intermittent problem may be caused by a poor connec-
tion, rubbed through wire insulation, or a broken wire in-
side the insulation.Test Description
The number(s) below refer to step(s) on the diagnostic
table.
3. This step checks for the ECM providing a ground
for the operation of the fuel pump relay.
7. By confirming that the wiring is OK using Steps 2
through 6, it can be determined that the fuel pump
relay is at fault.
9. After determining that there is no ground being pro-
vided by the ECM to the fuel pump relay, the fault is
either the ECM or the wiring between the ECM and
the fuel pump relay.

ENGINE CONTROLS 1F – 69
DAEWOO V–121 BL4
Fuel Pump Relay Circuit Check (1.8L DOHC)
StepActionValue(s)YesNo
11. Turn the ignition OFF for 10 seconds.
2. Turn the ignition ON.
3. Listen for in–tank fuel pump operation.
Does the fuel pump operate for the time specified?2 secSystem OKGo to Step 2
21. Turn the ignition OFF.
2. Disconnect the fuel pump relay.
3. Connect a test light between the fuel pump
relay connector terminal 30 and ground.
Turn the ignition ON. Is the test light on?–Go to Step 3Go to Step 8
31. Turn the ignition OFF.
2. Connect a test light between the fuel pump
relay connector terminal 85 and battery posi-
tive.
3. Turn the ignition ON.
4. With the ignition ON, the test light should light
for the time specified.
Is the test light on?2 secGo to Step 4Go to Step 9
41. Turn the ignition OFF.
2. Connect a test light between the fuel pump
relay connector terminal 30 and ground.
Is the test light on?–Go to Step 5Go to Step 11
5Check for an open or short to ground in the wire be-
tween the fuel pump relay connector terminal 87 and
the fuel pump connector terminal 3.
Is the problem found?–Go to Step 6Go to Step 7
61. Repair the wire between the fuel pump relay
connector terminal 87 and the fuel pump con-
nector terminal 3.
2. Install the fuel pump relay.
3. Turn the ignition OFF for 10 seconds.
4. Turn the ignition ON.
Does the fuel pump operate for the time specified?2 secSystem OK–
71. Replace the fuel pump relay.
2. Turn the ignition OFF for 10 seconds.
3. Turn the ignition ON.
Does the fuel pump operate for the time specified?2 secSystem OK–
8Check for an open wire between the fuel pump relay
connector terminal 30 and the battery.
Is the problem found?–Go to Step 13–
9Check for an open wire between the fuel pump relay
connector terminal 85 to the engine control module
(ECM) connector terminal K54
Is the problem found.–Go to Step 10Go to Step 12
101. Repair the wire between the fuel pump relay
connector terminal 85 to the ECM connector
terminal K54.
2. Install the fuel pump relay.
3. Turn the ignition OFF for 10 seconds.
4. Turn the ignition ON.
Does the fuel pump operate for the time specified?2 secSystem OK–

ENGINE CONTROLS 1F – 71
DAEWOO V–121 BL4
MAIN RELAY CIRCUIT CHECK (1.4L/1.6L DOHC)
Circuit Description
When the ignition is turned On or to the START position,
the main relay is energized. The main relay then supply
voltage to the engine fuse block fuse Ef11. The Electronic
Ignition (EI) system ignition coil, Evaporative Emission
(EVAP) Canister Purge Solenoid and Heated Oxygen
Sensor (HO2S) are supplied voltage through the engine
fuse block fuse Ef11. The fuel injectors are supplied volt-
age through the engine fuse block fuse Ef11.Diagnostic Aids
S An intermittent problem may be caused by a poor
connection, rubbed through wire insulation, or a
broken wire inside the insulation.
S A fault main relay will cause a no start condition.
There will be no voltage supplied to the EI system
ignition coil, or the fuel injectors. Without voltage
supplied to these components, they will not oper-
ate.
Main Relay Circuit Check (1.4L/1.6L DOHC)
StepActionValue(s)YesNo
11. Turn the ignition OFF.
2. Disconnect the engine fuse block fuse Ef11.
3. Turn the ignition ON.
4. With a test light connected to the ground,
probe the fuse terminals nearest the main relay
for fuse Ef11.
Is the light on at both terminal?–System OKGo to Step 2
2Is the light on at only one terminal?–Go to Step 3Go to Step 4
3Repair the open in the wiring between the main relay
connector terminal 87 and the fuse Ef11.
Is the repair complete?–System OK–