ground DAEWOO LACETTI 2004 Service Manual PDF

ENGINE CONTROLS 1F – 73
DAEWOO V–121 BL4
MAIN RELAY CIRCUIT CHECK (1.8L 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 F2. 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 F2. The fuel injectors are supplied voltage
through the engine fuse block fuse F2.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 (1.8L DOHC)
StepActionValue(s)YesNo
11. Turn the ignition OFF.
2. Disconnect the I/P fuse block fuse F2.
3. Turn the ignition ON.
4. With a test light connected to the ground,
probe the fuse terminals nearest the ignition
relay for fuse F2.
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 ignition
relay connector terminal 87 and the fuse F2.
Is the repair complete?–System OK–

1F – 74IENGINE CONTROLS
DAEWOO V–121 BL4
StepNo Yes Value(s) Action
41. Turn the ignition OFF.
2. Remove the ignition relay.
3. Turn the ignition ON.
4. With a test light connected to the ground,
probe the ignition relay terminals 85.
Is the light on at both terminals.–Go to Step 6Go to Step 5
51. Turn the ignition OFF.
2. Measure the resistance between following ter-
minals.
S Terminal 86 of main relay and ground.
Is the resistance within the specified value0 WGo to Step 7Go to Step 6
6Repair open circuit.
Is the repair complete?–System OK–
7Replace the ignition relay.
Is the repair complete?–System OK–

1F – 80IENGINE CONTROLS
DAEWOO V–121 BL4
Idle Air Control System Check (1.4L/1.6L DOHC)
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”
2Turn the ignition switch to ON.
Is the Malfunction Indicator Lamp (MIL) on steady?–Go to Step 4Go to Step 3
3Turn the ignition switch to LOCK.
Connect the scan tool to the DLC.
Turn the Turn the ignition switch to ON.
Are any diagnostic trouble codes (DTCs) displayed?–Go to Step 4Try with
another scan
tool
4Refer to the applicable DTC table.
Is only one DTC identified as valid trouble code
P0122?–Go to Step 5Go to
applicable DTC
table And go to
”Multiple DTC”
51. Connect the scan tool to the DLC.
2. Turn the ignition switch to ON.
3. Press the accelerator pedal while watching
TPS for smooth changes in the voltage.
Does the scan tool show the TPS voltage change
smoothly within the value specified?0.3V–4.8VGo to
”Diagnostic
Aids”Go to Step 6
61. Turn the ignition switch to lock.
2. Disconnect the MTIA connector.
3. Measure the voltage between terminal 2 and 8.
Does the voltage measure within the value speci-
fied?4.8V–5.0VGo to Step 7Go to Step 8
7Connect a fused jumper between the MTIA connec-
tor terminal 2 and terminal 7.
Does the scan tool show the TPS voltage above val-
ue specified?4.8V–5.0VGo to Step 13Go to Step 11
8Measure the voltage between the MTIA connector
2 and ground.
Does the voltage measure within the value speci-
fied?>5.0VGo to Step 9Go to Step 10
91. Turn the ignition switch to lock.
2. Check for an open or low voltage in the wire
between the MTIA connector 8 and ECM con-
nector 19.
Is the problem found?–Go to Step 12Go to Step 14
101. Turn the ignition switch to LOCK.
2. Check for an open or low voltage in the wire
between the MTIA connector 2 and ECM con-
nector 79.
Is the problem found?–Go to Step 12Go to Step 14
111. Turn the ignition switch to LOCK.
2. Check for an open or low voltage in the wire
between the MTIA connector 7 and ECM con-
nector 74.
Is the problem found?–Go to Step 12Go to Step 14

ENGINE CONTROLS 1F – 85
DAEWOO V–121 BL4
IGNITION SYSTEM CHECK (1.4L/1.6L DOHC)
Circuit Description
The Electronic Ignition (EI) system uses a waste spark
method of spark distribution. In this type of EI system, the
Crankshaft Position (CKP) sensor is mounted to the oil
pump near a slotted wheel that is a part of the crankshaft
pulley. The CKP sensor sends reference pulses to the en-
gine control module (ECM). The ECM then triggers the EI
system ignition coil. Once the ECM triggers the EI system
ignition coil, both of the connected spark plugs fire at the
same time. One cylinder is on its compression stroke at
the same time that the other is on the exhaust stroke, re-
sulting in lower energy needed to fire the spark plug in the
cylinder on its exhaust stroke.
This leaves the remainder of the high voltage to be used
to fire the spark plug in the cylinder on its compression
stroke. Since the CKP sensor is in a fixed position, timing
adjustments are not possible or needed.
Test Description
The number(s) below refer to step(s) on the diagnostictable.
2. It is important to check for the presence of spark to
all of the cylinders to isolate the problem to either
EI system ignition coil inputs or outputs.
5. In checking the ECM outputs for the electronic
spark timing signal, it recommended to use an os-
cilloscope to view the varying voltage signals. In
measuring these outputs with a voltmeter, intermit-
tent errors may occur that cannot be seen by a volt-
meter.
6. After confirming ECM inputs for the electronic spark
timing to the EI system ignition coil are OK, it can
be determined that a faulty EI system ignition coil is
at fault.
11. After confirming proper CKP sensor inputs to the
ECM and no wiring problems present, it can be de-
termined that the ECM is at fault.
24. This step, along with step 25, checks for battery
voltage and a ground to the EI system ignition coil.
Ignition System Check (1.4L/1.6L DOHC)
CAUTION : Use only electrically insulated pliers when handling ignition wires with the engine running to prevent
an electrical shock.
Step
ActionValue(s)YesNo
11. Remove the spark plugs.
2. Inspect for wet spark plugs, cracks, wear, im-
proper gap, burned electrodes, or heavy de-
posits.
3. Replace the spark plugs as needed.
Is the repair complete?–System OKGo to Step 2
2Check for the presence of spark from all of the igni-
tion wires while cranking the engine.
Is spark present from all of the ignition wires?–System OKGo to Step 3
31. Measure the resistance of the ignition wires.
2. Replace any ignition wire(s) with a resistance
above the value specified.
3. Check for the presence of spark from all of the
ignition wires.
Is spark present from all of the ignition wires?30,000 WSystem OKGo to Step 4
4Is spark present from at least one of the ignition
wires, but not all of the ignition wires?–Go to Step 5Go to Step 12
51. Turn the ignition OFF.
2. Disconnect the Electronic Ignition (EI) system
ignition coil connector.
3. While cranking the engine, measure the volt-
age at the EI system ignition coil connector
terminal 1.
Does the voltage fluctuate within the values speci-
fied?0.2–2.0 vGo to Step 6Go to Step 7

1F – 86IENGINE CONTROLS
DAEWOO V–121 BL4
StepNo Yes Value(s) Action
6While cranking the engine, measure the voltage at
the EI system ignition coil connector terminal 1.
Does the voltage fluctuate within the values speci-
fied?0.2–2.0 vGo to Step 10Go to Step 8
7Check for an open in the wire from the EI system
ignition coil connector terminal 1 to the engine con-
trol module (ECM) connector terminal 31.
Is the problem found?–Go to Step 9Go to Step 11
8Check for an open in the wire from the EI system
ignition coil connector terminal 1 to the ECM connec-
tor terminal 32.
Is the problem found?–Go to Step 9Go to Step 11
91. Repair the wiring as needed.
2. Connect the EI system ignition coil connector.
3. Check for the presence of spark from all of the
ignition wires.
Is spark present from all of the ignition wires?–System OK–
101. Turn the ignition OFF.
2. Replace the electronic ignition system ignition
coil.
3. Connect the EI system ignition coil connector.
4. Check for the presence of spark from all of the
ignition wires.
Is spark present from all of the ignition wires?–System OK–
111. Turn the ignition OFF.
2. Replace the ECM.
3. Connect the EI system ignition coil connector.
4. Check for the presence of spark from all of the
ignition wires.
Is spark present from all of the ignition wires?–System OK–
121. Turn the ignition OFF.
2. Disconnect the Crankshaft Position (CKP) sen-
sor connector.
3. Measure the resistance between the CKP sen-
sor terminals 1 and 2.
Is the resistance within the value specified?400–600 WGo to Step 13Go to Step 28
131. Measure the resistance between the CKP sen-
sor terminals 1 and 3.
2. Measure the resistance between the CKP sen-
sor terminals 2 and 3.
3. Is the resistance infinite (open circuit)?
Is the repair complete?–Go to Step 14Go to Step 28
141. Turn the ignition ON.
2. Measure the voltage between the CKP sensor
connector terminals 1 and 3.
Is the voltage within the value specified?1.3–1.5 v
(2.4–2.7 v)*Go to Step 20Go to Step 15
15Measure the voltage between the CKP sensor con-
nector terminal 1 and ground.
Is the voltage within the value specified?1.3–1.5 v
(2.4–2.7 v)*Go to Step 17Go to Step 16

ENGINE CONTROLS 1F – 87
DAEWOO V–121 BL4
StepNo Yes Value(s) Action
16Check the wire between the CKP sensor connector
terminal 1 and the ECM connector terminal 85 for an
open or short.
Is the problem found?Go to Step 18Go to Step 11
17Check the wire between the CKP sensor connector
terminal 3 and ground for an open or short.
Is the problem found?–Go to Step 19Go to Step 11
18Repair the wire between the CKP sensor connector
terminal 1 and the ECM connector terminal 85.
Is the repair complete?–System OK–
19Repair the wire between the CKP sensor connector
terminal 3 and ground.
Is the repair complete?–System OK–
201. Turn the ignition ON.
2. Measure the voltage between the CKP sensor
connector terminals 2 and 3.
Is the voltage within the value specified?1.3–1.5 v
(2.4–2.7 v)*Go to Step 24Go to Step 21
21Measure the voltage between the CKP sensor con-
nector terminal 2 and ground.
Is the voltage within the value specified?1.3–1.5 v
(2.4–2.7 v)*Go to Step 17Go to Step 22
22Check the wire between the CKP sensor connector
terminal 2 and the ECM connector terminal 54 for an
open or short.
Is the problem found?–Go to Step 23Go to Step 11
23Repair the wire between the CKP sensor connector
terminal 2 and the ECM connector terminal 54.
Is the repair complete?–System OK–
241. Turn the ignition OFF.
2. Connect a test light between the EI system
ignition coil connector terminal 2 and ground.
3. Turn the ignition ON.
Is the test light on?–Go to Step 25Go to Step 26
25Connect a test light between the EI system ignition
coil connector terminal 2 and battery positive.
Is the test light on?–Go to Step 5Go to Step 27
26Check for an open or short to ground in the wiring be-
tween the EI system ignition coil connector, terminal
2 and the ignition switch.
Is the problem found?–Go to Step 29–
27Repair the wire between the EI system ignition coil
connector terminal 1 and ground.
Is the repair complete?–System OK–
281. Turn the ignition OFF.
2. Replace the CKP sensor.
Is the repair complete?–System OK–
29Replace the fuse F2 or repair the open in the wiring
between the EI system ignition coil connector termi-
nal 2 and the ignition switch.
Is the repair complete?–System OK–

1F – 88IENGINE CONTROLS
DAEWOO V–121 BL4
IGNITION SYSTEM CHECK (1.8L DOHC)
Circuit Description
The Electronic Ignition (EI) system uses a waste spark
method of spark distribution. In this type of EI system, the
Crankshaft Position (CKP) sensor is mounted to the oil
pump near a slotted wheel that is a part of the crankshaft
pulley. The CKP sensor sends reference pulses to the en-
gine control module (ECM). The ECM then triggers the EI
system ignition coil. Once the ECM triggers the EI system
ignition coil, both of the connected spark plugs fire at the
same time. One cylinder is on its compression stroke at
the same time that the other is on the exhaust stroke, re-
sulting in lower energy needed to fire the spark plug in the
cylinder on its exhaust stroke.
This leaves the remainder of the high voltage to be used
to fire the spark plug in the cylinder on its compression
stroke. Since the CKP sensor is in a fixed position, timing
adjustments are not possible or needed.
Test Description
The number(s) below refer to step(s) on the diagnostictable.
2. It is important to check for the presence of spark to
all of the cylinders to isolate the problem to either
EI system ignition coil inputs or outputs.
5. In checking the ECM outputs for the electronic
spark timing signal, it recommended to use an os-
cilloscope to view the varying voltage signals. In
measuring these outputs with a voltmeter, intermit-
tent errors may occur that cannot be seen by a volt-
meter.
6. After confirming ECM inputs for the electronic spark
timing to the EI system ignition coil are OK, it can
be determined that a faulty EI system ignition coil is
at fault.
11. After confirming proper CKP sensor inputs to the
ECM and no wiring problems present, it can be de-
termined that the ECM is at fault.
24. This step, along with step 25, checks for battery
voltage and a ground to the EI system ignition coil.

1F – 90IENGINE CONTROLS
DAEWOO V–121 BL4
StepNo Yes Value(s) Action
101. Turn the ignition OFF.
2. Replace the electronic ignition system ignition
coil.
3. Connect the EI system ignition coil connector.
4. Check for the presence of spark from all of the
ignition wires.
Is spark present from all of the ignition wires?–System OK–
111. Turn the ignition OFF.
2. Replace the ECM.
3. Connect the EI system ignition coil connector.
4. Check for the presence of spark from all of the
ignition wires.
Is spark present from all of the ignition wires?–System OK–
121. Turn the ignition OFF.
2. Disconnect the Crankshaft Position (CKP) sen-
sor connector.
3. Measure the resistance between the CKP sen-
sor terminals 1 and 2.
Is the resistance within the value specified?400–600 WGo to Step 13Go to Step 28
131. Measure the resistance between the CKP sen-
sor terminals 1 and 3.
2. Measure the resistance between the CKP sen-
sor terminals 2 and 3.
3. Is the resistance infinite (open circuit)?
Is the repair complete?–Go to Step 14Go to Step 28
141. Turn the ignition ON.
2. Measure the voltage between the CKP sensor
connector terminals 1 and 3.
Is the voltage within the value specified?1.3–1.5 v
(2.4–2.7 v)*Go to Step 20Go to Step 15
15Measure the voltage between the CKP sensor con-
nector terminal 1 and ground.
Is the voltage within the value specified?1.3–1.5 v
(2.4–2.7 v)*Go to Step 17Go to Step 16
16Check the wire between the CKP sensor connector
terminal 1 and the ECM connector terminal M21 for
an open or short.
Is the problem found?Go to Step 18Go to Step 11
17Check the wire between the CKP sensor connector
terminal 3 and ground for an open or short.
Is the problem found?–Go to Step 19Go to Step 11
18Repair the wire between the CKP sensor connector
terminal 1 and the ECM connector terminal M21.
Is the repair complete?–System OK–
19Repair the wire between the CKP sensor connector
terminal 3 and ground.
Is the repair complete?–System OK–
201. Turn the ignition ON.
2. Measure the voltage between the CKP sensor
connector terminals 2 and 3.
Is the voltage within the value specified?1.3–1.5 v
(2.4–2.7 v)*Go to Step 24Go to Step 21

ENGINE CONTROLS 1F – 91
DAEWOO V–121 BL4
StepNo Yes Value(s) Action
21Measure the voltage between the CKP sensor con-
nector terminal 2 and ground.
Is the voltage within the value specified?1.3–1.5 v
(2.4–2.7 v)*Go to Step 17Go to Step 22
22Check the wire between the CKP sensor connector
terminal 2 and the ECM connector terminal M5 for
an open or short.
Is the problem found?–Go to Step 23Go to Step 11
23Repair the wire between the CKP sensor connector
terminal 2 and the ECM connector terminal M5.
Is the repair complete?–System OK–
241. Turn the ignition OFF.
2. Connect a test light between the EI system
ignition coil connector terminal 2 and ground.
3. Turn the ignition ON.
Is the test light on?–Go to Step 25Go to Step 26
25Connect a test light between the EI system ignition
coil connector terminal 2 and battery positive.
Is the test light on?–Go to Step 5Go to Step 27
26Check for an open or short to ground in the wiring be-
tween the EI system ignition coil connector, terminal
2 and the ignition switch.
Is the problem found?–Go to Step 29–
27Repair the wire between the EI system ignition coil
connector terminal 1 and ground.
Is the repair complete?–System OK–
281. Turn the ignition OFF.
2. Replace the CKP sensor.
Is the repair complete?–System OK–
29Replace the fuse Ef10 or repair the open in the wiring
between the EI system ignition coil connector termi-
nal 2 and the ignition switch.
Is the repair complete?–System OK–

ENGINE CONTROLS 1F – 93
DAEWOO V–121 BL4
ENGINE COOLING FAN CIRCUIT CHECK – DUAL FAN
(1.4L/1.6L DOHC)
Circuit Description
The engine cooling fan circuit operates the main cooling
fan and the auxiliary cooling fan. The cooling fans are con-
trolled by the engine control module (ECM) based on in-
puts from the Engine Coolant Temperature (ECT) sensor
and the Air Conditioning Pressure (ACP) sensor. The
ECM controls the low speed cooling fan operation by inter-
nally grounding the ECM connector terminal 10. This ener-
gizes the low speed cooling fan relay and operates the
main cooling fan and the auxiliary cooling fan at low speed
as the cooling fans are connected in a series circuit. The
ECM controls the high speed cooling fan operation by in-
ternally grounding the ECM connector terminal 10 and the
ECM connector terminal 9 at the same time. This ener-
gizes the low speed cooling fan relay, the high speed cool-
ing fan relay, and the series/parallel cooling fan relay re-
sulting in high speed fan operation as the cooling fans are
now connected in a parallel circuit.
Diagnostic Aids
S If the owner complained of an overheating problem,
it must be determined if the complaint was due to
an actual boil over, or the engine coolant tempera-
ture gauge indicated overheating. If the engine is
overheating and the cooling fans are on, the cooling
system should be checked.
S If the engine fuse block fuses Ef11 become open
(blown) immediately after installation, inspect for a
short to ground in the wiring of the appropriate cir-
cuit. If the fuses become open (blown) when the
cooling fans are to be turned on by the ECM, sus-
pect a faulty cooling fan motor.
S The ECM will turn the cooling fans on at low speed
when the coolant temperature is 97°C (207°F). The
ECM will turn the cooling fans off when the coolant
temperature is 94°C(201°F).
S The ECM will turn the cooling fans on at high speed
when the coolant temperature is 101°C (214°F).
The ECM will change the cooling fans from high
speed to low speed when the coolant temperature
is 98°C (208°F).S The ECM will turn the cooling fans on at low speed
when the A/C system is on. The ECM will change
the cooling fans from low speed to high speed
when the high side A/C pressure is 1882 kPa (273
psi) then return to low speed when the high side
A/C pressure is 1448 kPa (210 psi). When the A/C
system is on, the ECM will change the cooling fans
from low to high speed when the coolant tempera-
ture reaches 117°C (244°F) then return to low
speed when the coolant temperature reaches
11 4°C (237°F).
S The cooling fan circuit can be checked quickly by
disconnecting the ECM connector 2 and grounding
the connector terminal 10. This should create low
speed cooling fan operation with the ignition ON. By
grounding the ECM connector terminals 10 and 9
and turning the ignition ON, high speed cooling fan
operation should be achieved.
Test Description
The number(s) below refer to step(s) on the diagnostic
table.
4. This step, along with step 5, checks for the ability of
the ECM to operate the cooling fans.
8. This step, along with step 9, checks for the ability of
the ECM to operate the cooling fans in response to
A/C pressure readings.
16. After confirming battery voltage and the ECM sup-
plying a ground to the coil side of the cooling fan
relay A, by jumpering connector terminals 30 and
87 it will be determined if the relay is at fault or a
wiring problem is present.
31. This step checks for the presence of battery volt-
age to the main cooling fan when the A/C is on. If
battery voltage is present and the cooling fans are
not operating, the problem is in the ground side of
the cooling fan circuit.
37. By directly grounding the ECM connector terminals
10 and 9, the main and auxiliary cooling fans
should run at high speed.
Engine Cooling Fan Circuit Check – Dual Fan (1.4L/1.6L DOHC)
StepActionValue(s)YesNo
1Perform an On–Board Diagnostic (EOBD) system
check.
Is the check completed?–Go to Step 2Go to
”On–Board
Diagnostic Sys-
tem Check”
21. Check the engine fuse block fuse Ef11.
2. Replace the fuse as needed.
Is the fuse OK?–Go to Step 3Go to
”Diagnostic
Aids”