2004 DAEWOO LACETTI spark

ENGINE CONTROLS 1F – 47
DAEWOO V–121 BL4
ENGINE CRANKS BUT WILL NOT RUN (1.8L DOHC)
Test Description
The number(s) below refer to step(s) on the diagnostic
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 occurred. The information is then stored on the
scan tool for later reference.
2. By performing a compression test, it can be deter-
mined if the engine has the mechanical ability to
run.
3. It is important to check for the presence of sparkfrom all of the ignition wires. If spark is present from
one to three of the ignition coil terminals, the Crank-
shaft Position (CKP) sensor is OK.
19. In checking the engine control module (ECM) out-
puts for the electronic spark timing signal, it recom-
mended to use an oscilloscope to view the varying
voltage signals. In measuring these outputs with a
voltmeter, intermittent errors may occur that cannot
be seen by a voltmeter.
35. This step checks for proper operation of the ECM’s
control of the fuel pump circuit.
59. This step checks for a ground signal being supplied
by the ECM to operate the fuel injectors. If there is
no ground present during the cranking of the en-
gine, and the fuel injector wiring is OK, the ECM is
at fault.
Engine Cranks But Will Not Run (1.8L DOHC)
CAUTION : Use only electrically insulated pliers when
handling ignition wires with the engine running to
prevent an electrical shock.
CAUTION : Do not pinch or restrict nylon fuel lines.Damage to the lines could cause a fuel leak, resulting
in possible fire or personal injury.
Step
ActionValue(s)YesNo
1Perform an On–Board Diagnostic (EOBD) System
Check.
Was the check performed?–Go to Step 2Go to
”On–Board
Diagnostic
(EOBD) Sys-
tem Check”
2Check for set Diagnostic Trouble Code (DTC)
P0601.
Is the DTC set?–Go to applica-
ble DTC tableGo to Step 4
3Crank the engine.
Does the engine start and continue to run?–System OKGo to Step 5
4Perform a cylinder compression test.
Is the cylinder compression for all of the cylinders at
or above the value specified?689 kPa
(100 psi)Go to Step 8Go to Step 5
5Inspect the timing belt alignment.
Is the timing belt in alignment?–Go to Step 7Go to Step 6
6Align or replace the timing belt as needed.
Is the repair complete?–Go to Step 3–
7Repair the internal engine damage as needed.
Is the repair complete?–Go to Step 3–
8Inspect the fuel pump fuse.
Is the problem found?–Go to Step 9Go to Step 10
9Replace the fuse.
Is the repair complete?–Go to Step 3–
101. Install a scan tool.
2. Turn the ignition ON, the engine OFF and close
the throttle.
Does the Throttle Position (TP) sensor read less
than the specified value.1.0 vGo to Step 11Go to ”DTC
P0123 Throttle
Position Sensor
High Voltage”

1F – 48IENGINE CONTROLS
DAEWOO V–121 BL4
StepNo Yes Value(s) Action
11Compare the Engine Coolant Temperature (ECT)
with the Intake Air Temperature (IAT).
Is the ECT relatively close to the IAT?–Go to Step 12Go to ”DTC
P0118 Engine
Coolant Tem-
perature High
Voltage
121. Check if the Manifold Absolute Pressure (MAP)
sensor reading is over the specified reading.
2. Crank the engine while watching the MAP sen-
sor reading.
Does the MAP sensor read above the specified val-
ue and then change while cranking the engine?4 vGo to Step 13Go to Step 14
13Crank the engine.
Does the Crankshaft Position (CKP) Active Counter
increment while cranking?–Go to Step 16Go to Step 18
14Check the scan data for serial data.
Was serial data lost while cranking the engine?–Go to Step 15Go to ”MAP
Sensor Output
Check”
15Repair voltage loss to the engine control module
(ECM) from the ignition switch.
Is the repair complete?–System OK–
16Check 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?–Go to Step 41Go to Step 17
171. Measure the resistance of the ignition wires.
2. Replace any of the ignition wire(s) with a resist-
ance 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 WGo to Step 3Go to Step 18
181. Turn the ignition OFF.
2. Disconnect the Crankshaft Position (CKP) sen-
sor connector.
3. Measure the voltage between the CKP connec-
tor terminals 1 and 3.
4. Repair the wiring as needed.
Does the voltage measure near the value specified?1.4 v (2.5 v)*Go to Step 19Go to Step 20
19Measure the voltage between the CKP connector
terminals 2 and 3.
Does the voltage measure near the value specified1.4 v (2.5 v)*Go to Step 26Go to Step 21
20Measure the voltage between the CKP connector
terminals 1 and ground.
Does the voltage measure near the value specified?1.4 v (2.5 v)*Go to Step 22Go to Step 23
21Measure the voltage between the CKP connector
terminals 2 and ground.
Does the voltage measure near the value specified?1.4 v (2.5 v)*Go to Step 22Go to Step 24
22Check for an open or short in the wire between the
CKP connector terminal 3 and ground.
Is the problem found?–Go to Step 25Go to Step 40
23Check for an open or short in the wire between the
CKP connector terminal 1 and the ECM connector
terminal M21
Is the problem found?–Go to Step 25Go to Step 40

ENGINE CONTROLS 1F – 49
DAEWOO V–121 BL4
StepNo Yes Value(s) Action
24Check for an open or short in the wire between the
CKP connector terminal 2 and the ECM connector
terminal M5.
Is the problem found?–Go to Step 25Go to 40
25Repair the wiring as needed.
Is the repair complete?–Go to Step 3–
261. Disconnect the Electronic Ignition (EI) system
ignition coil connector to prevent the vehicle
from starting.
2. Measure the voltage at the ECM connector
terminal M21 by backprobing the ECM connec-
tor.
Are the voltage readings near the values specified?1.4 v (2.5 v)*
with ignition
ON, 1.6 v (2.6
v)* during
crankingGo to Step 27Go to Step 28
27Measure the voltage at the ECM connector terminal
M5 by backprobing the ECM connector.
Are the voltage readings near the values specified?1.4 v (2.5 v)*
with ignition
ON, 1.6 v (2.6
v)* during
crankingGo to Step 29Go to Step 28
28Replace the CKP sensor.
Is the repair complete?–Go to Step 3–
291. Turn the ignition OFF.
2. Disconnect the electrical connector at the EI
system ignition coil.
3. Connect a test light between terminal 2 of the
EI system ignition coil connector and ground.
4. Turn the ignition ON.
Is the test light on?–Go to Step 30Go to Step 31
30Connect a test light of the EI system ignition coil con-
nector and battery positive.
Is the test light on?–Go to Step 34Go to Step 32
31Check for an open in the wiring between the ignition
switch and the EI system ignition coil connector ter-
minal 3.
Is the problem found?–Go to Step 33–
32Check for an open in the wire from the EI system
ignition coil to ground.
Is the problem found?–Go to Step 2–
331. 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?–Go to Step 3Go to Step 34
341. Turn the ignition OFF.
2. Disconnect the EI system ignition coil connec-
tor.
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 39Go to Step 37

1F – 50IENGINE CONTROLS
DAEWOO V–121 BL4
StepNo Yes Value(s) Action
35While cranking the engine, measure the voltage at
the EI system ignition coil connector terminal 3 .
Does the voltage fluctuate within the values speci-
fied?0.2–2.0 vGo to Step 39Go to Step 37
36Check for an open in the wire from the EI system
ignition coil connector terminal 1 to the ECM connec-
tor terminal M51.
Is the problem found?–Go to Step 38Go to Step 40
37Check for an open in the wire from the EI system
ignition coil connector terminal 3 to the ECM connec-
tor terminal M1.
Is the problem found?–Go to Step 38Go to Step 40
381. 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?–Go to Step 3Go to Step 39
39Replace the EI system ignition coil.
Is the repair complete?–Go to Step 3–
401. Turn the ignition OFF.
2. Replace the ECM.
Is the repair complete?–Go to Step 3–
411. Turn the ignition OFF.
2. Connect a fuel pressure gauge.
3. Crank the engine.
Is any fuel pressure present?–Go to Step 44Go to Step 42
421. Turn the ignition OFF.
2. Disconnect the electrical connector at the fuel
pump.
3. Connect a test light between the fuel pump
connector terminals 3 and 2.
4. Turn the ignition ON.
5. With the ignition ON, the test light should light
for the time specified.
Is the test light on?2 secGo to Step 43Go to Step 53
43Replace the fuel pump.
Is the repair complete?–Go to Step 3–
44Is the fuel pressure within the value specified?283–324 kPa
(41–47 psi)Go to Step 48Go to Step 45
451. Check the fuel filter for a restriction.
2. Inspect the fuel lines for kinks and restrictions.
Is the problem found?–Go to Step 46Go to Step 47
461. Disconnect the vacuum line from the fuel pres-
sure regulator.
2. Inspect the vacuum line for the presence of
fuel.
3. Inspect the fuel pressure regulator vacuum port
for the presence of fuel.
Is any fuel present?283–324 kPa
(41–47 psi)Go to Step 3Go to Step 47

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

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.

ENGINE CONTROLS 1F – 89
DAEWOO V–121 BL4
Ignition System Check (1.8L 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
6While cranking the engine, measure the voltage at
the EI system ignition coil connector terminal 3
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 M35 or M51.
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 3 to the ECM connec-
tor terminal M1 or M33.
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–