Daewoo Nubira. Service manual - part 116

 

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Daewoo Nubira. Service manual - part 116

 

 

1F – 46

I

ENGINE CONTROLS

DAEWOO V–121 BL4

Step

No

Yes

Value(s)

Action

12

Replace the PCM/ECM.
Is the repair complete?

Go to Step 22

13

Repair the short to voltage in the MIL control circuit.
Is the repair complete?

Go to Step 22

14

Check for an open or a poor connection in the MIL
control circuit and repair as necessary.
Is the repair necessary?

Go to Step 22

Go to Step 17

15

With a test light still connected to the ground, probe
the ignition feed terminal F16.
Does the test light illuminate?

Go to Step 18

Go to Step 19

16

Repair the open battery feed circuit.
Is the repair complete?

Go to Step 22

17

Check for an open ignition feed circuit or fuse to the
MIL and repair as necessary.
Is the repair necessary?

Go to Step 22

Go to Step 20

18

Check for a poor connection in the battery feed ter-
minal A4 or the ignition feed terminal F16 and repair
as necessary.
Is the repair necessary?

Go to Step 22

Go to Step 21

19

Repair the open in the ignition feed circuit from termi-
nal F16.
Is the repair complete?

Go to Step 22

20

Replace the instrument panel cluster. Refer to Sec-
tion 9E, Instrumentation/Driver Information.
Is the repair complete?

Go to Step 22

21

Check for a faulty PCM/ECM ground connection at
the engine block or PCM/ECM connector and repair
as necessary.
Is the repair necessary?

Go to Step 22

Go to Step 12

22

1.  Allow the engine to idle until normal operating

temperature is reached.

2.  Check if any Diagnostic Trouble Codes (DTCs)

are set.

Are any DTCs displayed that have not been diag-
nosed?

Go to the appli-

cable DTC

table

System OK

ENGINE CONTROLS  1F – 47

DAEWOO V–121 BL4

MALFUNCTION INDICATOR LAMP ON STEADY

Circuit Description
When the ignition is turned ON, the Malfunction Indicator
Lamp (MIL) will momentarily flash on and off, then it will re-
main 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
powertrain control module (PCM)/engine control 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 (OBD II) System Check
prompts the technician to complete some basic
checks and store the freeze frame and failure re-

cords data on then 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 mo-
mentarily flash on and off, then remain on until the
engine is running or if an emission related DTC is
stored.

3.

This step checks the ability of the PCM/ECM to
control the MIL. The scan tool has the ability to
command the MIL on and off.

5.

A shorted MIL circuit can be diagnosed with a scan
tool.

7.

The replacement PCM/ECM must be repro-
grammed. Refer to the latest Techline information
for reprogramming procedures.

1F – 48

I

ENGINE CONTROLS

DAEWOO V–121 BL4

Malfunction Indicator Lamp On Steady

Step

Action

Value(s)

Yes

No

1

Perform an On–Board Diagnostic (OBD II) System
Check.
Is the system check complete?

Go to Step 2

Go to ”On–

Board Diagnos-

tic System

Check”

2

Turn the ignition switch ON, with the engine OFF.
Is the Malfunction Indicator Lamp (MIL) on?

Go to Step 3

Go to ”No Mal-

function Indica-

tor Lamp”

3

1.  Install the scan tool.
2.  Command the MIL on and off.

Does the MIL turn on and off when commanded?

Go to Step 8

Go to Step 4

4

1.  Turn the ignition switch OFF.
2.  Disconnect the powertrain control module

(PCM)/engine control module (ECM) connec-
tors.

3.  Turn the ignition switch ON.

Is the MIL off?

Go to Step 7

Go to Step 5

5

Check the MIL control circuit for a short to ground
and repair if necessary.
Is the repair necessary?

Go to Step 8

Go to Step 6

6

Replace the instrument panel cluster. Refer to Sec-
tion 9E, Instrumentation/Driver Information.
Is the repair complete?

Go to Step 8

7

Replace the PCM/ECM.
Is the repair complete?

Go to Step 8

8

1.  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 9

Go to Step 1

9

1.  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 the appli-

cable DTC

table

System OK

ENGINE CONTROLS  1F – 49

DAEWOO V–121 BL4

FUEL SYSTEM DIAGNOSIS

Circuit Description

The fuel pump is an in–tank fuel pump mounted to a fuel
sender assembly. The fuel pump will remain on as long as
the engine is cranking or running and the powertrain con-
trol module (PCM)/engine control module (ECM) is receiv-
ing reference pulses from the crankshaft position (CKP)
sensor. If there are no reference pulses, the PCM/ECM
will turn off the fuel pump 2 seconds after the ignition
switch is turned ON or 2 seconds after the engine 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 reg-
ulator. 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

Step

Action

Value(s)

Yes

No

1

1.  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

(41–47 psi)

Go to Step 2

Go to Step 5

2

1.  Disconnect the fuel pressure regulator vacuum

hose.

2.  Start the engine.
3.  Allow the engine to idle.
4.  Connect the fuel pressure regulator vacuum

hose.

Does the fuel pressure decrease?

System OK

Go to Step 3

3

1.  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 4

Go to Step 16

4

1.  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

 

 

 

 

 

 

 

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