ECU DAEWOO NUBIRA 2004 Service Repair Manual

1F – 632IENGINE CONTROLS
DAEWOO V–121 BL4
READING DIAGNOSTIC TROUBLE
CODES
The procedure for reading diagnostic trouble code(s) is to
use a diagnostic scan tool. When reading Diagnostic
Trouble Codes (DTCs), follow the instructions supplied by
tool manufacturer.
DTC Modes
On On–Board Diagnostic (EOBD) passenger cars there
are five options available in the scan tool DTC mode to dis-
play the enhanced information available. A description of
the new modes, DTC Info and Specific DTC, follows. After
selecting DTC, the following menu appears:
S DTC Info.
S Specific DTC.
S Freeze Frame.
S Fail Records (not all applications).
S Clear Info.
The following is a brief description of each of the sub me-
nus in DTC Info and Specific DTC. The order in which they
appear here is alphabetical and not necessarily the way
they will appear on the scan tool.
DTC Information Mode
Use the DTC info mode to search for a specific type of
stored DTC information. There are seven choices. The
service manual may instruct the technician to test for
DTCs in a certain manner. Always follow published service
procedures.
To get a complete description of any status, press the ”En-
ter” key before pressing the desired F–key. For example,
pressing ”Enter” then an F–key will display a definition of
the abbreviated scan tool status.
DTC Status
This selection will display any DTCs that have not run dur-
ing the current ignition cycle or have reported a test failure
during this ignition up to a maximum of 33 DTCs. DTC
tests which run and pass will cause that DTC number to
be removed from the scan tool screen.
Fail This Ign. (Fail This Ignition)
This selection will display all DTCs that have failed during
the present ignition cycle.
History
This selection will display only DTCs that are stored in the
ECM’s history memory. It will not display type CNL DTCs
that have not requested the Malfunction Indicator Lamp
(MIL). It will display all type A, B and E DTCs that have re-
quested the MIL and have failed within the last 40 warm–
up cycles. In addition, it will display all type C and type D
DTCs that have failed within the last 40 warm–up cycles.
Last Test Fail
This selection will display only DTCs that failed the last
time the test ran. The last test may have run during a pre-
vious ignition cycle if a type A or type B DTC is displayed.
For type C and type D DTCs, the last failure must have oc-
curred during the current ignition cycle to appear as Last
Test Fail.
MIL Request
This selection will display only DTCs that are requesting
the MIL. Type C and type D DTCs cannot be displayed us-
ing this option. This selection will report type B DTCs only
after the MIL has been requested.
Not Run SCC (Not Run Since Code Clear)
This option will display up to 33 DTCs that have not run
since the DTCs were last cleared. Since any displayed
DTCs have not run, their condition (passing or failing) is
unknown.
Test Fail SCC (Test Failed Since Code
Clear)
This selection will display all active and history DTCs that
have reported a test failure since the last time DTCs were
cleared. DTCs that last failed more than 40 warm–up
cycles before this option is selected will not be displayed.
Specific DTC Mode
This mode is used to check the status of individual diag-
nostic tests by DTC number. This selection can be ac-
cessed if a DTC has passed, failed or both. Many EOBD
DTC mode descriptions are possible because of the ex-
tensive amount of information that the diagnostic execu-
tive monitors regarding each test. Some of the many pos-
sible descriptions follow with a brief explanation.
The ”F2” key is used, in this mode, to display a description
of the DTC. The ”Yes” and ”No” keys may also be used to
display more DTC status information. This selection will
only allow entry of DTC numbers that are supported by the
vehicle being tested. If an attempt is made to enter DTC
numbers for tests which the diagnostic executive does not
recognize, the requested information will not be displayed
correctly and the scan tool may display an error message.
The same applies to using the DTC trigger option in the
Snapshot mode. If an invalid DTC is entered, the scan tool
will not trigger.
Failed Last Test
This message display indicates that the last diagnostic
test failed for the selected DTC. For type A and type B
DTCs, this message will be displayed during subsequent
ignition cycles until the test passes or DTCs are cleared.
For type C and type D DTCs, this message will clear when
the ignition is cycled.
Failed Since Clear
This message display indicates that the DTC has failed at
least once within the last 40 warm–up cycles since the last
time DTCs were cleared.

ENGINE CONTROLS 1F – 633
DAEWOO V–121 BL4
Failed This Ig. (Failed This Ignition)
This message display indicates that the diagnostic test
has failed at least once during the current ignition cycle.
This message will clear when DTCs are cleared or the igni-
tion is cycled.
History
This message display indicates that the DTC has been
stored in memory as a valid fault. A DTC displayed as a
History fault may not mean that the fault is no longer pres-
ent. The history description means that all the conditions
necessary for reporting a fault have been met (maybe
even currently), and the information was stored in the con-
trol module memory.
MIL Requested
This message display indicates that the DTC is currently
causing the MIL to be turned ON. Remember that only
type A and type B DTCs can request the MIL. The MIL re-
quest cannot be used to determine if the DTC fault condi-
tions are currently being experienced. This is because the
diagnostic executive will require up to three trips during
which the diagnostic test passes to turn OFF the MIL.
Not Run Since CI (Not Run Since Cleared)
This message display indicates that the selected diagnos-
tic test has not run since the last time DTCs were cleared.
Therefore, the diagnostic test status (passing or failing) is
unknown. After DTCs are cleared, this message will con-
tinue to be displayed until the diagnostic test runs.
Not Run This Ig. (Not Run This Ignition)
This message display indicates that the selected diagnos-
tic test has not run during this ignition cycle.
Test Ran and Passed
This message display indicates that the selected diagnos-
tic test has done the following:
S Passed the last test.
S Run and passed during this ignition cycle.
S Run and passed since DTCs were last cleared.
If the indicated status of the vehicle is ”Test Ran and
Passed” after a repair verification, the vehicle is ready to
be released to the customer.
If the indicated status of the vehicle is ”Failed This Ignition”
after a repair verification, then the repair is incomplete and
further diagnosis is required.
Prior to repairing a vehicle, status information can be used
to evaluate the state of the diagnostic test, and to help
identify an intermittent problem. The technician can con-
clude that although the MIL is illuminated, the fault condi-
tion that caused the code to set is not present. An intermit-
tent condition must be the cause.
PRIMARY SYSTEM – BASED
DIAGNOSTICS
There are primary system–based diagnostics which eval-
uate system operation and its effect on vehicle emissions.
The primary system–based diagnostics are listed below
with a brief description of the diagnostic function:
Oxygen Sensor Diagnosis
The fuel control Front Heated Oxygen Sensor (HO2S1) is
diagnosed for the following conditions:
S Slow response.
S Response time (time to switch R/L or L/R).
S Inactive signal (output steady at bias voltage
approx. 450 mv).
S Signal fixed high.
S Signal fixed low.
The catalyst monitor Rear Heated Oxygen Sensor
(HO2S2) is diagnosed for the following conditions:
S Heater performance (time to activity on cold start).
S Signal fixed low during steady state conditions or
power enrichment (hard acceleration when a rich-
mixture should be indicated).
S Signal fixed high during steady state conditions or
deceleration mode (deceleration when a lean mix-
ture should be indicated).
S Inactive sensor (output steady at approximately 438
mv).
If the oxygen sensor pigtail wiring, connector or terminal
are damaged, the entire oxygen sensor assembly must be
replaced. Do not attempt to repair the wiring, connector or
terminals. In order for the sensor to function properly, it
must have clean reference air provided to it. This clean air
reference is obtained by way of the oxygen sensor wire(s).
Any attempt to repair the wires, connector or terminals
could result in the obstruction of the reference air and de-
grade oxygen sensor performance.
Misfire Monitor Diagnostic Operation
The misfire monitor diagnostic is based on crankshaft
rotational velocity (reference period) variations. The en-
gine control module (ECM) determines crankshaft rota-
tional velocity using the Crankshaft Position (CKP) sensor
and the Camshaft Position (CMP) sensor. When a cylinder
misfires, the crankshaft slows down momentarily. By mon-
itoring the CKP and CMP sensor signals, the ECM can cal-
culate when a misfire occurs.
For a non–catalyst damaging misfire, the diagnostic will be
required to monitor a misfire present for between
1000–3200 engine revolutions.
For catalyst–damaging misfire, the diagnostic will respond
to misfire within 200 engine revolutions.
Rough roads may cause false misfire detection. A rough
road will cause torque to be applied to the drive wheels and
drive train. This torque can intermittently decrease the
crankshaft rotational velocity. This may be falsely de-
tected as a misfire.

1F – 634IENGINE CONTROLS
DAEWOO V–121 BL4
A rough road sensor, or G sensor, works together with the
misfire detection system. The G sensor produces a volt-
age that varies along with the intensity of road vibrations.
When the ECM detects a rough road, the misfire detection
system is temporarily disabled.
Misfire Counters
Whenever a cylinder misfires, the misfire diagnostic
counts the misfire and notes the crankshaft position at the
time the misfire occurred. These ”misfire counters” are ba-
sically a file on each engine cylinder. A current and a histo-
ry misfire counter are maintained for each cylinder. The
misfire current counters (Misfire Cur #1–4) indicate the
number of firing events out of the last 200 cylinder firing
events which were misfires. The misfire current counter
will display real time data without a misfire Diagnostic
Trouble Code (DTC) stored. The misfire history counters
(Misfire Hist #1–4) indicate the total number of cylinder fir-
ing events which were misfires. The misfire history count-
ers will display 0 until the misfire iagnostic has failed and
a DTC P0300 is set. Once the misfire DTC P0300 is set,
the misfire history counters will be updated every 200 cyl-
inder firing events. A misfire counter is maintained for each
cylinder.
If the misfire diagnostic reports a failure, the diagnostic
executive reviews all of the misfire counters before report-
ing a DTC. This way, the diagnostic executive reports the
most current information.
When crankshaft rotation is erratic, a misfire condition will
be detected. Because of this erratic condition, the data
that is collected by the diagnostic can sometimes incor-
rectly identify which cylinder is misfiring.
Use diagnostic equipment to monitor misfire counter data
on On–Board Diagnostic (EOBD) compliant vehicles.
Knowing which specific cylinder(s) misfired can lead to the
root cause, even when dealing with amultiple cylinder mis-
fire. Using the information in the misfire counters, identify
which cylinders are misfiring. If the counters indicate cylin-
ders numbers 1 and 4 misfired, look for a circuit or compo-
nent common to both cylinders number 1 and 4.
The misfire diagnostic may indicate a fault due to a tempo-
rary fault not necessarily caused by a vehicle emission
system malfunction. Examples include the following
items:
S Contaminated fuel.S Low fuel.
S Fuel–fouled spark plugs.
S Basic engine fault.
Fuel Trim System Monitor Diagnostic
Operation
This system monitors the averages of short–term and
long–term fuel trim values. If these fuel trim values stay at
their limits for a calibrated period of time, a malfunction is
indicated. The fuel trim diagnostic compares the averages
of short–term fuel trim values and long–term fuel trim val-
ues to rich and lean thresholds. If either value is within the
thresholds, a pass is recorded. If both values are outside
their thresholds, a rich or lean DTC will be recorded.
The fuel trim system diagnostic also conducts an intrusive
test. This test determines if a rich condition is being
caused by excessive fuel vapor from the Evaporative
(EVAP) Emission canister. In order to meet EOBD require-
ments, the control module uses weighted fuel trim cells to
determine the need to set a fuel trim DTC. A fuel trim DTC
can only be set if fuel trim counts in the weighted fuel trim
cells exceed specifications. This means that the vehicle
could have a fuel trim problem which is causing a problem
under certain conditions (i.e., engine idle high due to a
small vacuum leak or rough idle due to a large vacuum
leak) while it operates fine at other times. No fuel trim DTC
would set (although an engine idle speed DTC or HO2S2
DTC may set). Use a scan tool to observe fuel trim counts
while the problem is occurring.
A fuel trim DTC may be triggered by a number of vehicle
faults. Make use of all information available (other DTCs
stored, rich or lean condition, etc.) when diagnosing a fuel
trim fault.
Fuel Trim Cell Diagnostic Weights
No fuel trim DTC will set regardless of the fuel trim counts
in cell 0 unless the fuel trim counts in the weighted cells are
also outside specifications. This means that the vehicle
could have a fuel trim problem which is causing a problem
under certain conditions (i.e. engine idle high due to a
small vacuum leak or rough due to a large vacuum leak)
while it operates fine at other times. No fuel trim DTC
would set (although an engine idle speed DTC or HO2S2
DTC may set). Use a scan tool to observe fuel trim counts
while the problem is occurring.

1G – 6IENGINE EXHAUST
DAEWOO V–121 BL4
6. Install the crossmember lower bracket bolts to 35
NSm (26 lb–ft).
MUFFLER – FRONT
Removal Procedure
1. Remove the nuts and the gasket from the front
muffler pipe to the exhaust front pipe flange.
2. Disconnect the front muffler from the rubber hang-
er.
3. Remove the nuts and the gasket from the rear muf-
fler pipe flange.
4. Remove the front muffler.
5. Check the exhaust pipe and the front muffler for
holes, damage, open seams, or other deterioration
which could permit exhaust fumes to seep into the
passenger compartment or the trunk.
Installation Procedure
1. Connect the front muffler to the rubber hanger.
2. Attach the front muffler and the gasket to the rear
muffler using the nuts. Secure the front muffler to
the rubber hanger.
Tighten
Tighten the front muffler–to–rear muffler nuts to 30
NSm (22 lb–ft).

ENGINE EXHAUST 1G – 7
DAEWOO V–121 BL4
3. Loosely secure the front muffler assembly to the
connecting pipe flange.
4. Secure the front muffler assembly to the connecting
pipe flange with the nuts.
Tighten
Tighten the front muffler–to–exhaust front pipe nuts to
30 NSm (22 lb–ft).
MUFFLER – REAR
Removal Procedure
1. Remove the nuts and the gasket from the rear muf-
fler pipe flange–to–front muffler pipe flange.
2. Detach the rear muffler assembly from the rubber
hangers on the tail pipe end.
3. Remove the rear muffler assembly.
4. Check the rear muffler and the pipe for holes, dam-
age, open seams, and other deterioration which
could permit exhaust fumes to seep into the pas-
senger compartment or the trunk.
Installation Procedure
1. Secure the rear muffler assembly to the rubber
hangers on the tail pipe end.

1G – 8IENGINE EXHAUST
DAEWOO V–121 BL4
2. Secure the nuts and the gasket from the rear muf-
fler pipe flange–to–front muffler pipe flange.
Tighten
Tighten the front muffler–to–rear muffler nuts to 30
NSm (22 lb–ft).

2C – 16IFRONT SUSPENSION
DAEWOO V–121 BL4
5. Install the control arm–to–crossmember bolts.
Tighten
S Tighten the front control arm–to–crossmember
bolt to 125 NSm (92 lb–ft).
S Tighten the rear control arm–to–crossmember
bolt to 110 NSm (81 lb–ft).
6. Install the wheel. Refer to Section 2E, Tires and
Wheels.
7. Lower the vehicle.
STRUT ASSEMBLY
Removal Procedure
1. Remove the strut upper cap and nut.
2. Raise and suitably support the vehicle.
3. Remove the wheel. Refer to Section 2E, Tires and
Wheels.
4. On vehicles equipped with an antilock braking sys-
tem (ABS), disconnect the ABS sensor line from
the strut assembly.
5. Remove the brake line from the securing bracket
on the strut assembly.
6. Disconnect the stabilizer shaft link by removing the
stabilizer link–to–strut assembly nut.

2C – 18IFRONT SUSPENSION
DAEWOO V–121 BL4
3. Connect the stabilizer shaft link to the strut assem-
bly by attaching the stabilizer link–to–strut assem-
bly nut.
Tighten
Tighten the stabilizer link–to–strut assembly nut to 47
NSm (35 lb–ft).
4. Install the brake line to the securing bracket on the
strut assembly.
5. On vehicles equipped with the ABS, connect the
ABS sensor line to the strut assembly.
6. Install the wheel. Refer to Section 2E, Tires and
Wheels.
7. Lower the vehicle.
8. Install the nuts securing the strut assembly to the
body of the vehicle.
Tighten
Tighten the strut assembly–to–body nuts to 65 NSm
(48 lb–ft).
CROSSMEMBER ASSEMBLY
Removal Procedure
1. Raise and suitably support the vehicle.
2. Remove the wheels. Refer to Section 2E, Tires and
Wheels.
3. Remove the nuts and bolts from the steering gear
mounting bracket.
4. Remove the return line bolt from the clip on the
crossmember.
5. Remove the exhaust pipe forward of the catalytic
converter. Refer to Section 1G, Engine Exhaust.
6. Disconnect the tie rod from the knuckle assembly.
Refer to Section 6C, Power Steering Gear.
7. Disconnect the ball joint from the knuckle assembly.
Refer to ”Knuckle Assembly” in this section.
8. Disconnect the stabilizer link from the strut assem-
bly. Refer to ”Stabilizer Link” in this section.
9. Remove the crossmember link–to–transaxle brack-
et nut.
1) Remove the right lower engine mount.
2) Remove the rear transmission mount bracket.

REAR SUSPENSION 2D – 7
DAEWOO V–121 BL4
7. Remove the stabilizer link–to–strut assembly nut
and disconnect the stabilizer link from the strut as-
sembly.
8. Remove the knuckle–to–strut assembly nuts and
the bolts.
9. On vehicles equipped with rear drum brakes, lower
the strut assembly and separate the brake line from
the strut assembly.
10. Remove the rear strut assembly from the vehicle.
Installation Procedure
Important : On vehicles equipped with rear drum brakes,
the brake hose will easily connect to the strut assembly as
the assembly is being installed into the vehicle. On ve-
hicles equipped with rear disc brakes, the brake hose can
be connected to the strut assembly at any time after the
strut assembly has been installed into the vehicle.
1. Install the rear strut assembly into the vehicle. On
vehicles equipped with rear drum brakes, secure
the brake line into the holder as the assembly goes
into place.

2D – 8IREAR SUSPENSION
DAEWOO V–121 BL4
2. Secure the strut assembly by loosely attaching the
strut mount–to–body nuts.
3. Install the knuckle–to–strut assembly nuts and
bolts. Do not tighten.
4. Install the clip holding the brake hose to the strut
assembly.
Tighten
Tighten the knuckle–to–strut assembly nuts to 100
NSm (74 lb–ft).
5. Connect the stabilizer link to the strut assembly and
install the stabilizer link–to–strut assembly nut.
Tighten
Tighten the stabilizer link–to–strut assembly nut to 47
NSm (35 lb–ft).
6. Connect the parking brake. Refer to Section 4G,
Parking Brake.
7. Install the wheel. Refer to Section 2E, Tires and
Wheels.
8. Lower the vehicle.
Tighten
Tighten the strut mount–to–body nuts to 30 NSm (22
lb–ft).