lock DAEWOO LACETTI 2004 Service Repair Manual

ENGINE CONTROLS 1F – 437
DAEWOO V–121 BL4
8. Check the fuel for water, alcohol, etc.
9. A basic engine problem that affects all cylinders is
the only possibility at this point. (Cam timing,
throttle body leak, restricted air flow, etc.)
11. Tests the ignition system voltage output using a
spark tester.
12. Replace any spark plugs that are worn, cracked or
fouled.
13. Checks for voltage at the ignition feed circuit.
18. Whenever the driver circuit is shorted to ground,
the light will be on steady. When the driver circuit is
shorted to voltage or open, the light will be off.19. Since voltage is supplied to the fuel injector on a
single circuit, the malfunction could only be a poor
connection or open in the fuel injector harness. An
open before the harness would result in an ”Engine
Cranks But Will Not Run” complaint.
28. Before replacing the ECM, check terminals for im-
proper mating, broken locks, or physical damage to
the wiring harness. The replacement ECM must be
programmed. Refer to the latest Techline procedure
for ECM reprogramming.
DTC P0303 – Cylinder 3 Misfire
StepActionValue(s)YesNo
1Perform an On–Board Diagnostic (EOBD) System
Check.
Was the check complete?–Go to Step 2Go to
”On–Board
Diagnostic Sys-
tem Check”
21. Install a scan tool to the Data Link Connector
(DLC).
2. Turn the ignition ON, with the engine OFF.
3. Request Diagnostic Trouble Codes (DTCs)
Are DTCs P0203 or P300 set?–Go to applica-
ble DTCGo to Step 3
31. Perform a visual/physical inspection.
2. Make any repairs that are necessary.
Is the repair complete?–Go to Step 27Go to Step 4
4Start the engine and allow it to idle.
Are any Misfire Current counters incrementing?–Go to Step 5Go to Step 6
5Are all counters equal (within a percentage of each
other)?–Go to Step 7Go to Step 11
61. Turn the ignition ON, with the engine OFF.
2. Review the Freeze Frame data, and note the
parameters.
3. Operate the vehicle within the Freeze Frame
conditions and conditions for setting this DTC
as noted.
Are any Misfire Current counters incrementing?–Go to Step 5Go to
”Diagnostic
Aids”
71. Turn the engine OFF.
2. Install a fuel pressure gauge to the fuel rail.
3. Observe the fuel pressure with the engine run-
ning.
Is the fuel pressure within the specified value?284–325 kPa
(41–47 psi)Go to Step 8Go to
”Fuel System
Diagnosis”
8Check the fuel for contamination.
Is the fuel OK?–Go to Step 9Go to Step 10
9Check for a basic engine problem and repair as nec-
essary.
Is the repair complete?–Go to Step 27–
10Replace the contaminated fuel.
Is the repair complete?–Go to Step 27–

ENGINE CONTROLS 1F – 441
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P0304
CYLINDER 4 MISFIRE
System Description
The Engine Control Module (ECM) monitors the crank-
shaft and camshaft positions to detect if the engine is mis-
firing. The ECM looks for a quick drop in crankshaft speed.
This test is executed in blocks of 100 engine revolution
tests. It may take between one to several tests to store a
Diagnostic Trouble Code (DTC) and illuminate the Mal-
function Indicator Lamp (MIL). Under light misfire condi-
tions, it may also take more than one trip to set a DTC. Se-
vere misfire will flash the MIL, indicating that catalyst
damage is possible.
Conditions for Setting the DTC
S Emission threshold is 3%.
S 20 engine cycles have occurred since cranking has
started.
S A/C compressor clutch has not just engaged or dis-
engaged.
S Engine load and engine speed is in a detectable
region and is at or above zero torque.
S Camshaft Position (CMP) sensor is in synchroniza-
tion.
S Exhaust Gas Recirculation (EGR) flow diagnostic is
not in progress.
S Fuel level is greater than 12% of rated tank capac-
ity.
S Decel Fuel Cutoff (DFCO) not active.
S Throttle position change is less than 3% per 125
ms.
S Vehicle has not encountered an abusive engine
speed of 7000 rpm.
S Crankshaft speed patters are normal.
S Throttle position is less than 3% when vehicle
speed is greater than 10 km/h (6 mph).
S Vehicle voltage is between 11 and 16 volts.
S Engine Coolant Temperature (ECT) is between
–7°C (19°F) and 120°C (248°F).
S There is the correct ratio between Crankshaft Posi-
tion (CKP) sensor pulses and CMP sensor pulses.
S DTCs P0106, P0107, P0108, P0117, P0118,
P0122, P0123, P0336, P0337, P0341, P0342 and
P0502 are not set.
Action Taken When the DTC Sets
S The MIL will illuminate after two consecutive ignition
cycles in which the diagnostic runs with the fault
active.
Or
S The MIL will illuminate immediately and flash if mis-
fire is present.
S The ECM will record operating conditions at the
time the diagnostic fails. This information will be
stored in the Freeze Frame and Failure Records
buffers.S A history DTC is stored.
Conditions for Clearing the MIL/DTC
S The MIL will turn off after four consecutive ignition
cycles in which the diagnostic runs without a fault
within the freeze frame conditions that the DTC
failed.
S A history DTC will clear after 40 consecutive warm–
up cycles without a fault.
S The DTC(s) can be cleared by using the scan tool.
S Disconnecting the ECM battery feed for more than
10 seconds.
Diagnostic Aids
An intermittent can also be the result of a defective reluctor
wheel. Remove the CKP sensor and inspect the reluctor
wheel through the sensor mount hole. Check for porosity
and the condition of wheel. If the DTC is intermittent refer
to”Symptoms Diagnosis” in this section.
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 then
stored on the scan tool for later reference.
3. A visual/physical inspection should include check-
ing the following components:
S The wiring for proper connections, pinches or
cuts.
S The ECM grounds for being clean and tight.
S The vacuum hoses for splits, kinks, and proper
connections as shown on the Vehicle Emission
Information label. Check thoroughly for any type
of leak or restriction.
S For air leaks at the throttle body mounting area
and intake manifold sealing surfaces.
5. When all the accumulators are relatively equal, then
the misfire is being caused by something that af-
fects the entire engine. When they are not then the
misfire is being caused by something that is specif-
ic to two or more cylinders.
6. Whenever the misfire is not present operating the
vehicle may be necessary to duplicate the condi-
tions in the Freeze Frame Data in order to detect
misfire. Depending on the engine load, the condi-
tions may have to be maintained for up to 20 sec-
onds. Whenever the misfire accumulators start to
increment, then misfire is present. A history misfire
counter will store the number of misfires that have
occurred until the DTC is cleared.

1F – 442IENGINE CONTROLS
DAEWOO V–121 BL4
8. Check the fuel for water, alcohol, etc.
9. A basic engine problem that affects all cylinders is
the only possibility at this point. (Cam timing,
throttle body leak, restricted air flow, etc.)
11. Tests the ignition system voltage output using a
spark tester.
12. Replace any spark plugs that are worn, cracked or
fouled.
13. Checks for voltage at the ignition feed circuit.
18. Whenever the driver circuit is shorted to ground,
the light will be on steady. When the driver circuit is
shorted to voltage or open, the light will be off.19. Since voltage is supplied to the fuel injector on a
single circuit, the malfunction could only be a poor
connection or open in the fuel injector harness. An
open before the harness would result in an ”Engine
Cranks But Will Not Run” complaint.
28. Before replacing the ECM, check terminals for im-
proper mating, broken locks, or physical damage to
the wiring harness. The replacement ECM must be
programmed. Refer to the latest Techline procedure
for ECM reprogramming.
DTC P0304 – Cylinder 4 Misfire
StepActionValue(s)YesNo
1Perform an On–Board Diagnostic (EOBD) System
Check.
Was the check complete?–Go to Step 2Go to
”On–Board
Diagnostic Sys-
tem Check”
21. Install a scan tool to the Data Link Connector
(DLC).
2. Turn the ignition ON, with the engine OFF.
3. Request Diagnostic Trouble Codes (DTCs)
Are DTCs P0201 or P300 set?–Go to applica-
ble DTCGo to Step 3
31. Perform a visual/physical inspection.
2. Make any repairs that are necessary.
Is the repair complete?–Go to Step 27Go to Step 4
4Start the engine and allow it to idle.
Are any Misfire Current counters incrementing?–Go to Step 5Go to Step 6
5Are all counters equal (within a percentage of each
other)?–Go to Step 7Go to Step 11
61. Turn the ignition ON, with the engine OFF.
2. Review the Freeze Frame data, and note the
parameters.
3. Operate the vehicle within the Freeze Frame
conditions and conditions for setting this DTC
as noted.
Are any Misfire Current counters incrementing?–Go to Step 5Go to
”Diagnostic
Aids”
71. Turn the engine OFF.
2. Install a fuel pressure gauge to the fuel rail.
3. Observe the fuel pressure with the engine run-
ning.
Is the fuel pressure within the specified value?284–325 kPa
(41–47 psi)Go to Step 8Go to
”Fuel System
Diagnosis”
8Check the fuel for contamination.
Is the fuel OK?Go to Step 9Go to Step 10
9Check for a basic engine problem and repair as nec-
essary.
Is the repair complete?–Go to Step 27–
10Replace the contaminated fuel.
Is the repair complete?–Go to Step 27–

ENGINE CONTROLS 1F – 445
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P0317
ROUGH ROAD SENSOR SOURCE NOT DETECTED
System Description
The Engine Control Module (ECM) identifies engine mis-
fire by detecting variations in crankshaft speed. Crank-
shaft speed variations can also occur when a vehicle is op-
erating over a rough road. The ECM receives rough road
signal by gravity sensing rough road (G) sensor or Elec-
tronic Brake Control Module (EBCM) if equipped with the
Anti–Lock Brake System (ABS). The ABS can detect if the
vehicle is on the rough surface based on wheel accelera-
tion/deceleration data supplied by each wheel speed sen-
sor. This information sent to the ECM by EBCM through
serial data line. The G sensor is vertical low g–accelera-
tion sensor. By sensing vertical acceleration caused by
bumps or portholes in the road, the ECM determine if the
changes in crankshaft speed are due to engine misfire or
are driveline induced. If the ECM can not receive any of
those signal, a historic Diagnostic Trouble Code (DTC) will
be stored.
Conditions for Setting the DTCS ECM can not detect any rough road source.
S Vehicle speed is greater than 5km/h (3.1 mph).
Action Taken When the DTC Sets
S The MIL will not illuminate.
S The ECM will record operating conditions at the
time the diagnostic fails. This information will be
stored in the Failure Records buffers.
S A history DTC is stored.
Conditions for Clearing the MIL/DTC
S A history DTC will clear after 40 consecutive warm–
up cycles without a fault.
S The DTC(s) can be cleared by using the scan tool.
S Disconnecting the ECM battery feed for more than
10 seconds.
Diagnostic Aids
An open signal circuit of G sensor or open serial data line
between the ECM and the EBCM will be the cause of this
DTC.

1F – 446IENGINE CONTROLS
DAEWOO V–121 BL4
DTC P0317 – Rough Road Sensor Source Not Detected
StepActionValue(s)YesNo
1Perform an On–Board Diagnostic (EOBD) System
Check.
Was the check complete?–Go to Step 2Go to
”On–Board
Diagnostic Sys-
tem Check”
21. Install a scan tool to the Data Link Connector
(DLC).
2. Turn the ignition ON, with the engine OFF.
3. Request Diagnostic Trouble Codes (DTCs)
Are DTCs P1380, P1381, P1391, P1392 or P1393
set?–Go to
Applicable DTCGo to Step 3
3Is the vehicle equipped with the Anti–lock Brake
System (ABS)?–Go to Step 8Go to Step 4
41. Disconnect the gravity sensing rough road (G)
sensor connector.
2. Disconnect the Engine control Module (ECM)
connector.
3. Measure resistance between terminal B of the
G sensor and terminal K21 of the ECM.
Is the resistance within the specified value?0 ΩGo to Step 6Go to Step 5
5Repair open circuit.
Is the repair complete?–Go to Step 11Go to Step 6
61. Reconnect the ECM and G sensor connectors.
2. Turn the ignition ON.
3. Probe the voltage at terminal B of G sensor.
Is the voltage within the specified value?2.35–2.65 VGo to Step 10Go to Step 7
71. Turn the ignition OFF.
2. Replace the G sensor.
Is the repair complete?–Go to Step 11–
81. Turn the ignition OFF.
2. Disconnect the Electronic Brake Control Mod-
ule EBCM) connector and the ECM connector.
3. Measure the resistance between terminal 25 of
the EBCM and terminal K7 of the ECM.
Is the resistance within the specified value?0 ΩGo to Step 10Go to Step 9
9Repair open circuit.
Is the repair complete?–Go to Step 11Go to Step 10
101. Turn the ignition OFF.
2. Replace the ECM.
Is the repair complete?–Go to Step 11–
111. Using the scan tool, clear the DTCs.
2. Start the engine and idle at normal operating
temperature.
3. Operate the vehicle within the conditions for
setting this DTC as supported in the text.
Does the scan tool indicate that this diagnostic ran
and passed?–Go to Step 12Go to Step 2
12Check if any additional DTCs are set.
Are any DTCs displayed that have not been diag-
nosed?–Go to
Applicable DTC
tableSystem OK

ENGINE CONTROLS 1F – 447
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P0325
KNOCK SENSOR INTERNAL MALFUNCTION
System Description
The Knock Sensor (KS) system is used to detect engine
detonation, allowing the Engine Control Module (ECM) to
retard the ignition control spark timing based on the KS
signal being received. The KS produces an AC signal so
that under a no–knock condition the signal on the KS cir-
cuit measures about 0.007 volts AC. The KS signal’s am-
plitude and frequency depend upon the amount of knock
being experienced. The ECM contains a nonreplaceable
knock filter module called a Digitally Controlled Signal–to–
Noise Enhancement Filter (DSNEF) module. This filter
module in the ECM determines whether or not knock is oc-
curring by comparing the signal level on the KS circuit with
the voltage level on the noise channel. The noise channel
allows the ECM to reject any false knock signal by knowing
the amount of normal engine mechanical noise present.
Normal engine noise varies depending on engine speed
and load. When the ECM determines that an abnormally
low noise channel voltage level is being experienced,
Diagnostic Trouble Code (DTC) P0325 will set.
Conditions for Setting the DTC
S DSNEF A/D reading is less than 1.0% or greater
than 80% any of the 4 cylinders.
S Vacuum is less than the predetermined value (10 to
50 kPa, based on rpm).
S The rpm is greater than 1600.
S DTC(s) P0106, P0107, P0108 are not set.
Action Taken When the DTC Sets
S The Malfunction Indicator Lamp (MIL) will not illumi-
nate.
S The ECM will record operating conditions at the
time the diagnostic fails. This information will be
stored in the Failure Records buffers.
S A history DTC is stored.
Conditions for Clearing the MIL/DTCS A history DTC will clear after 40 consecutive warm–
up cycles without a fault.
S DTC(s) can be cleared by using the scan tool.
S Disconnecting the ECM battery feed for more than
10 seconds.
Diagnostic Aids
Check and correct any abnormal engine noise before us-
ing the diagnostic table.
Any circuitry, that is suspected as causing the complaint,
should be thoroughly checked for the following conditions:
S Backed–out terminals
S Improper mating
S Broken locks
S Improperly formed
S Damaged terminals
S Poor terminal–to–wire connection
S Physical damage to the wiring harness
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 then
stored on the scan tool for later reference.
2. If the conditions for the test as described above are
met, a DTC P0325 will set and MIL will illuminate.
4. If the engine has an internal knock or audible noise
that causes a knocking type noise on the engine
block, the knock sensor may be responding to the
noise.
6. The replacement ECM must be reprogrammed.
Refer to the latest Techline procedure for ECM re-
programming.
DTC P0325 – Knock Sensor Internal Malfunction
StepActionValue(s)YesNo
1Perform an On–Board Diagnostic (EOBD) System
Check.
Was the check performed?–Go to Step 2Go to
”On–Board
Diagnostic Sys-
tem Check”
21. Install a scan tool to the Data Link Connector
(DLC).
2. Clear the Diagnostic Trouble Codes (DTCs).
3. Start the engine.
4. Operate the vehicle within the Conditions for
Setting the DTC as noted.
Is the DTC set again.–Go to Step 3Go to Step 6

ENGINE CONTROLS 1F – 449
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P0327
KNOCK SENSOR CIRCUIT FAULT
System Description
The Knock Sensor (KS) system is used to detect engine
detonation, allowing the Engine Control Module (ECM) to
retard the ignition control spark timing based on the KS
signal being received. The KS produces an AC signal so
that under a no–knock condition the signal on the KS cir-
cuit measures about 0.007 volts AC. The KS signal’s am-
plitude and frequency depend upon the amount of knock
being experienced. The ECM monitors the KS signal and
can diagnose the KS and circuitry.
Conditions for Setting the DTC
S Minimum difference between cylinders is greater
than 0.4%.
S Vacuum is less than the predetermined value (10 to
50 kPa, based on rpm).
S The rpm is greater than 1600.
S DTC(s) P0106, P0107, P0108 are not set.
Action Taken When the DTC Sets
S The Malfunction Indicator Lamp (MIL) will not illumi-
nate.
S The ECM will record operating conditions at the
time the diagnostic fails. This information will be
stored in the Failure Records buffers.
S A history DTC is stored.
Conditions for Clearing the MIL/DTC
S A history DTC will clear after 40 consecutive warm–
up cycles without a fault.
S DTC(s) can be cleared by using the scan tool.
S Disconnecting the ECM battery feed for more than
10 seconds.Diagnostic Aids
Check and correct any abnormal engine noise before us-
ing the diagnostic table.
Any circuitry, that is suspected as causing the complaint,
should be thoroughly checked for the following conditions:
S Backed–out terminals
S Improper mating
S Broken locks
S Improperly formed
S Damaged terminals
S Poor terminal–to–wire connection
S Physical damage to the wiring harness
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 then
stored on the scan tool for later reference.
2. If the conditions for the test as described above are
met, a DTC P0327 will set and MIL will illuminate.
3. If the engine has an internal knock or audible noise
that causes a knocking type noise on the engine
block, the KS may be responding to the noise.
5. Checking the internal resistance of the KS or the
wiring to the KS is OK.
6. Any circuitry, that is suspected as causing the com-
plaint, should be thoroughly checked for backed–
out terminals, improper mating, broken locks, im-

1F – 452IENGINE CONTROLS
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P0336
58X CRANK POSITION SENSOR EXTRA/MISSING
PULSES
Circuit Description
The 58X reference signal is produced by the Crankshaft
Position (CKP) sensor. During one crankshaft revolution,
58 crankshaft pulses will be produced. The Engine Control
Module (ECM) uses the 58X reference signal to calculate
engine rpm and CKP. The ECM constantly monitors the
number of pulses on the 58X reference circuit and
compares them to the number of Camshaft Position
(CMP) signal pulses being received. If the ECM receives
and incorrect number of pulses on the 58X reference cir-
cuit, Diagnostic Trouble Code (DTC) P0336 will set.
Conditions for Setting the DTC
S Engine is running.
S Extra or missing pulses detected between consecu-
tive 58X reference pulses.
S Number of extra or missing teeth is greater than or
equal to 2 per revolution.
S Above condition is detected in 10 of 100 crankshaft
rotations.
Action Taken When the DTC Sets
S The Malfunction Indicator Lamp (MIL) will illuminate
after three consecutive ignition cycle with a fail.
S The ECM will record operating conditions at the
time the diagnostic fails. This information will be
stored in the Freeze Frame and Failure Records
buffer.
S A history DTC is stored.
Conditions for Clearing the MIL/DTCS The MIL will turn OFF after four consecutive igni-
tion cycles in which the diagnostic runs without a
fault.
S A history DTC will clear after 40 consecutive warm–
up cycles have occurred without a fault.
S The DTC(s) can be cleared using the scan tool.
S Disconnecting the ECM battery feed for more than
10 seconds.
Diagnostic Aids
An intermittent may be caused by a poor connection,
rubbed–through wire insulation or a wire broken inside the
insulation. Check for:
S Poor connection – Inspect the ECM harness and
connectors for improper mating, broken locks, im-
properly formed or damaged terminals, and poor
terminal–towire connections.
S Damaged harness – Inspect the wiring harness for
damage. If the harness appears to be OK, discon-
nect the ECM, turn the ignition ON and observe a
voltmeter connected to the 58X reference circuit at
the ECM harness connector while moving the con-
nectors and the wiring harnesses related to the
ECM. A change in voltage will indicate the location
of the fault.
S Reviewing the Failure Records vehicle mileage
since the diagnostic test last failed may help deter-
mine how often the condition that caused the DTC
to be set occurs. This may assist in diagnosing the
condition.

ENGINE CONTROLS 1F – 455
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P0337
58X CRANK POSITION SENSOR NO SIGNAL
Circuit Description
The 58X reference signal is produced by the Crankshaft
Position (CKP) sensor. During one crankshaft revolution,
58 crankshaft pulses will be produced. The Engine Control
Module (ECM) uses the 58X reference signal to calculate
engine rpm and CKP. The ECM constantly monitors the
number of pulses on the 58X reference circuit and
compares them to the number of Camshaft Position
(CMP) signal pulses being received. If the ECM does not
receive any 58X reference pulses on the 58X reference
circuit while cranking, Diagnostic Trouble Code (DTC)
P0337 will set.
Conditions for Setting the DTC
S 58X reference pulse not seen during cranking.
S DTCs P0341 and P0342 are not set.
S Change in voltage drop is greater than 0.5 volts and
change in Manifold Absolute Pressure (MAP) is
greater than 0.05kPa (0.07 psi).
S 58X reference pulse not seen for 0.078 seconds.
Action Taken When the DTC Sets
S The Malfunction Indicator Lamp (MIL) will illumi-
nate.
S The ECM will record operating conditions at the
time the diagnostic fails. This information will be
stored in the Freeze Frame and Failure Records
buffer.
S A history DTC is stored.
Conditions for Clearing the MIL/DTCS The MIL will turn OFF after four consecutive igni-
tion cycles in which the diagnostic runs without a
fault.
S A history DTC will clear after 40 consecutive warm–
up cycles have occurred without a fault.
S The DTC(s) can be cleared using the scan tool.
S Disconnecting the ECM battery feed for more than
10 seconds.
Diagnostic Aids
An intermittent may be caused by a poor connection,
rubbed–through wire insulation or a wire broken inside the
insulation. Check for:
S Poor connection – Inspect the ECM harness and
connectors for improper mating, broken locks, im-
properly formed or damaged terminals, and poor
terminal–towire connections.
S Damaged harness – Inspect the wiring harness for
damage. If the harness appears to be OK, discon-
nect the ECM, turn the ignition ON and observe a
voltmeter connected to the 58X reference circuit at
the ECM harness connector while moving the con-
nectors and the wiring harnesses related to the
ECM. A change in voltage will indicate the location
of the fault.
S Reviewing the Failure Records vehicle mileage
since the diagnostic test last failed may help deter-
mine how often the condition that caused the DTC
to be set occurs. This may assist in diagnosing the
condition.

1F – 458IENGINE CONTROLS
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P0341
CAMSHAFT POSITION SENSOR RATIONALITY
System Description
The Camshaft Position (CMP) Sensor is used to correlate
crankshaft to camshaft position so that the Engine Control
Module (ECM) can determine which cylinder is ready to be
fueled by the injector. The CMP is also used to determine
which cylinder is misfiring when a misfire is present. When
the ECM cannot use the information from the CMP sensor,
a Diagnostic Trouble Code (DTC) is set, and the ECM will
fuel the engine using the Alternating Synchronous Double
Fire (ASDF) method.
Conditions for Setting the DTC
S CMP Sensor reference pulse is not detected at the
correct interval every 4 cylinders.
S Engine is running.
Action Taken When the DTC Sets
S The Malfunction Indicator Lamp (MIL) will illuminate
after three consecutive ignition cycle with a fail.
S The ECM will record operating conditions at the
time the diagnostic fails. This information will be
stored in the Freeze Frame and Failure Records
buffers.
S A history DTC is stored.Conditions for Clearing the MIL/DTC
S The MIL will turn off after four consecutive ignition
cycles in which the diagnostic runs without a fault.
S A history DTC will clear after 40 consecutive warm–
up cycles without a fault.
S DTC(s) can be cleared by using the scan tool.
S Disconnecting the ECM battery feed for more than
10 seconds.
Diagnostic Aids
An intermittent problem may be caused by a poor connec-
tion, rubbed–through wire insulation, or a wire that is bro-
ken inside the insulation.
Any circuitry, that is suspected as causing the complaint,
should be thoroughly checked for the following conditions:
S Backed–out terminals
S Improper mating
S Broken locks
S Improperly formed
S Damaged terminals
S Poor terminal–to–wire connection
S Physical damage to the wiring harness
Anytime a poor connection is present, the CMP Reference
Activity counter will stop incrementing.