2004 DAEWOO LACETTI Crankshaft sensor

1F – 630IENGINE CONTROLS
DAEWOO V–121 BL4
COMPREHENSIVE COMPONENT
MONITOR DIAGNOSTIC OPERATION
Comprehensive component monitoring diagnostics are
required to monitor emissions–related input and output
powertrain components.
Input Components
Input components are monitored for circuit continuity and
out–of–range values. This includes rationality checking.
Rationality checking refers to indicating a fault when the
signal from a sensor does not seem reasonable, i.e.
Throttle Position (TP) sensor that indicates high throttle
position at low engine loads or Manifold Absolute Pressure
(MAP) voltage. Input components may include, but are not
limited to, the following sensors:
S Vehicle Speed Sensor (VSS).
S Crankshaft Position (CKP) sensor.
S Throttle Position (TP) sensor.
S Engine Coolant Temperature (ECT) sensor.
S Camshaft Position (CMP) sensor.
S Manifold Absolute Pressure (MAP) sensor.
In addition to the circuit continuity and rationality check,
the ECT sensor is monitored for its ability to achieve a
steady state temperature to enable closed loop fuel con-
trol.
Output Components
Output components are diagnosed for proper response to
control module commands. Components where functional
monitoring is not feasible will be monitored for circuit conti-
nuity and out–of–range values if applicable. Output com-
ponents to be monitored include, but are not limited to the
following circuit:
S Idle Air Control (IAC) Motor.
S Control module controlled EVAP Canister Purge
Valve.
S A/C relays.
S Cooling fan relay.
S VSS output.
S MIL control.
Refer to ”Engine Control Module” and Sensors in this sec-
tion.
Passive and Active Diagnostic Tests
A passive test is a diagnostic test which simply monitors
a vehicle system or component. Conversely, an active
test, actually takes some sort of action when performing
diagnostic functions, often in response to a failed passive
test. For example, the Exhaust Gas Recirculation (EGR)
diagnostic active test will force the EGR valve open during
closed throttle deceleration and/or force the EGR valve
closed during a steady state. Either action should result in
a change in manifold pressure.
Intrusive Diagnostic Tests
This is any on–board test run by the Diagnostic Manage-
ment System which may have an effect on vehicle perfor-
mance or emission levels.
Warm–Up Cycle
A warm–up cycle means that engine temperature must
reach aminimum of 160°F (70°C) and rise at least 72°F
(22°C) over the course of a trip.
Freeze Frame
Freeze Frame is an element of the Diagnostic Manage-
ment System which stores various vehicle information at
the moment an emissions–related fault is stored in
memory and when the Malfunction Indicator Lamp (MIL)
is commanded on. These data can help to identify the
cause of a fault.
Failure Records
Failure Records data is an enhancement of the EOBD
Freeze Frame feature. Failure Records store the same ve-
hicle information as does Freeze Frame, but it will store
that information for any fault which is stored in onboard
memory, while Freeze Frame stores information only for
emission–related faults that command the MIL on.
COMMON EOBD TERMS
Diagnostic
When used as a noun, the word diagnostic refers to any
on–board test run by the vehicle’s Diagnostic Manage-
ment System. A diagnostic is simply a test run on a system
or component to determine if the system or component is
operating according to specification. There are many diag-
nostics, shown in the following list:
S Misfire
S Front Heated Oxygen Sensor (HO2S1)
S Rear Heated Oxygen Sensor (HO2S2)
S Exhaust Gas Recirculation (EGR)
S Catalyst monitoring
Enable Criteria
The term ”enable criteria” is engineering language for the
conditions necessary for a given diagnostic test to run.
Each diagnostic has a specific list of conditions which
must be met before the diagnostic will run.
”Enable criteria” is another way of saying ”conditions re-
quired.”
The enable criteria for each diagnostic is listed on the first
page of the Diagnostic Trouble Code (DTC) description
under the heading ”Conditions for Setting the DTC.” En-
able criteria varies with each diagnostic and typically in-
cludes, but is not limited to, the following items:
S Engine speed.
S Vehicle speed
S Engine Coolant Temperature (ECT)
S Manifold Absolute Pressure (MAP)

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.