key DAEWOO MATIZ 2003 Service Repair Manual
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Page 108 of 1184
1F–10 ENGINE CONTROLS
DAEWOO M-150 BL2
fuels use alcohol to increase the octane rating of the
fuel. Although alcohol-enhanced fuels may raise the oc-
tane rating, the fuel’s ability to turn into vapor in cold
temperatures deteriorates. This may affect the starting
ability and cold driveability of the engine.
Low fuel levels can lead to fuel starvation, lean engine
operation, and eventually engine misfire.
Non-OEM Parts
The EOBD system has been calibrated to run with Origi-
nal Equipment Manufacturer (OEM) parts. Something
as simple as a high performance-exhaust system that
affects exhaust system back pressure could potentially
interfere with the operation of the Electric Exhaust Gas
Recirculation (EEGR) valve and thereby turn on the
MIL. Small leaks in the exhaust system near the heated
oxygen sensor (HO2S) can also cause the MIL to turn
on.
Aftermarket electronics, such as cellular phones, ster-
eos, and anti-theft devices, may radiate Electromagnet-
ic Interference (EMI) into the control system if they are
improperly installed. This may cause a false sensor
reading and turn on the MIL.
Environment
Temporary environmental conditions, such as localized
flooding, will have an effect on the vehicle ignition sys-
tem. If the ignition system is rain-soaked, it can tempo-
rarily cause engine misfire and turn on the MIL.
Vehicle Marshaling
The transportation of new vehicles from the assembly
plant to the dealership can involve as many as 60 key
cycles within 2 to 3 miles of driving. This type of opera-
tion contributes to the fuel fouling of the spark plugs and
will turn on the MIL with a set DTC P0300.
Poor Vehicle Maintenance
The sensitivity of the EOBD will cause the MIL to turn on
if the vehicle is not maintained properly. Restricted air fil-
ters, fuel filters, and crankcase deposits due to lack of oil
changes or improper oil viscosity can trigger actual ve-
hicle faults that were not previously monitored prior to
EOBD. Poor vehicle maintenance can not be classified
as a “non-vehicle fault,” but with the sensitivity of the
EOBD, vehicle maintenance schedules must be more
closely followed.
Severe Vibration
The Misfire diagnostic measures small changes in the
rotational speed of the crankshaft. Severe driveline
vibrations in the vehicle, such as caused by an exces-
sive amount of mud on the wheels, can have the same
effect on crankshaft speed as misfire and, therefore,
may set DTC P0300.
Related System Faults
Many of the EOBD system diagnostics will not run if the
Engine Control Module (ECM) detects a fault on a re-
lated system or component. One example would be thatif the ECM detected a Misfire fault, the diagnostics on
the catalytic converter would be suspended until the
Misfire fault was repaired. If the Misfire fault is severe
enough, the catalytic converter can be damaged due to
overheating and will never set a Catalyst DTC until the
Misfire fault is repaired and the Catalyst diagnostic is al-
lowed to run to completion. If this happens, the custom-
er may have to make two trips to the dealership in order
to repair the vehicle.
SERIAL DATA COMMUNICATIONS
Keyword 2000 Serial Data
Communications
Government regulations require that all vehicle
manufacturers establish a common communication sys-
tem. This vehicle utilizes the “Keyword 2000” commu-
nication system. Each bit of information can have one of
two lengths: long or short. This allows vehicle wiring to
be reduced by transmitting and receiving multiple sig-
nals over a single wire. The messages carried on Key-
word 2000 data streams are also prioritized. If two
messages attempt to establish communications on the
data line at the same time, only the message with higher
priority will continue. The device with the lower priority
message must wait. The most significant result of this
regulation is that it provides scan tool manufacturers
with the capability to access data from any make or
model vehicle that is sold.
The data displayed on the other scan tool will appear the
same, with some exceptions. Some scan tools will only
be able to display certain vehicle parameters as values
that are a coded representation of the true or actual val-
ue. On this vehicle, the scan tool displays the actual val-
ues for vehicle parameters. It will not be necessary to
perform any conversions from coded values to actual
values.
EURO ON-BOARD DIAGNOSTIC
(EOBD)
Euro On-Board Diagnostic Tests
A diagnostic test is a series of steps, the result of which
is a pass or fail reported to the diagnostic executive.
When a diagnostic test reports a pass result, the diag-
nostic executive records the following data:
The diagnostic test has been completed since the last
ignition cycle.
The diagnostic test has passed during the current
ignition cycle.
The fault identified by the diagnostic test is not cur-
rently active.
When a diagnostic test reports a fail result, the diagnos-
tic executive records the following data:
The diagnostic test has been completed since the last
ignition cycle.
Page 110 of 1184
1F–12 ENGINE CONTROLS
DAEWOO M-150 BL2
The enable criteria for each diagnostic is listed on the
first page of the Diagnostic Trouble Code (DTC) descrip-
tion under the heading “Conditions for Setting the DTC.”
Enable criteria varies with each diagnostic and typically
includes, but is not limited to the following items:
Engine speed.
Vehicle speed
Engine Coolant Temperature (ECT)
Manifold Absolute Pressure (MAP)
Barometric Pressure (BARO)
Intake Air Temperature (IAT)
Throttle Position (TP)
High canister purge
Fuel trim
A/C on
Trip
Technically, a trip is a key-on run key-off cycle in which
all the enable criteria for a given diagnostic are met, al-
lowing the diagnostic to run. Unfortunately, this concept
is not quite that simple. A trip is official when all the en-
able criteria for a given diagnostic are met. But because
the enable criteria vary from one diagnostic to another,
the definition of trip varies as well. Some diagnostics are
run when the vehicle is at operating temperature, some
when the vehicle first starts up; some require that the
vehicle cruise at a steady highway speed, some run only
when the vehicle is at idle. Some run only immediately
following a cold engine start-up.
A trip then, is defined as a key-on run-key off cycle in
which the vehicle is operated in such a way as to satisfy
the enable criteria for a given diagnostic, and this diag-
nostic will consider this cycle to be one trip. However,
another diagnostic with a different set of enable criteria
(which were not met) during this driving event, would not
consider it a trip. No trip will occur for that particular
diagnostic until the vehicle is driven in such a way as to
meet all the enable criteria.
Diagnostic Information
The diagnostic charts and functional checks are de-
signed to locate a faulty circuit or component through a
process of logical decisions. The charts are prepared
with the requirement that the vehicle functioned correct-
ly at the time of assembly and that there are not multiple
faults present.
There is a continuous self-diagnosis on certain control
functions. This diagnostic capability is complimented by
the diagnostic procedures contained in this manual. The
language of communicating the source of the malfunc-
tion is a system of diagnostic trouble codes. When a
malfunction is detected by the control module, a DTC is
set, and the Malfunction Indicator Lamp (MIL) is illumi-
nated.
Malfunction Indicator Lamp (MIL)
The Malfunction Indicator Lamp (MIL) is required by
Euro On-Board Diagnostics (EOBD) to illuminate under
a strict set of guidelines.
Basically, the MIL is turned on when the Engine Control
Module (ECM) detects a DTC that will impact the vehicle
emissions.
The MIL is under the control of the Diagnostic Execu-
tive. The MIL will be turned on if an emissions-related
diagnostic test indicates a malfunction has occurred. It
will stay on until the system or component passes the
same test for three consecutive trips with no emissions
related faults.
Extinguishing the MIL
When the MIL is on, the Diagnostic Executive will turn
off the MIL after three consecutive trips that a “test
passed” has been reported for the diagnostic test that
originally caused the MIL to illuminate. Although the MIL
has been turned off, the DTC will remain in the ECM
memory (both Freeze Frame and Failure Records) until
forty (40) warm-up cycles after no faults have been com-
pleted.
If the MIL was set by either a fuel trim or misfire-related
DTC, additional requirements must be met. In addition
to the requirements stated in the previous paragraph,
these requirements are as follows:
The diagnostic tests that are passed must occur with
375 rpm of the rpm data stored at the time the last
test failed.
Plus or minus ten percent of the engine load that was
stored at the time the last test failed. Similar engine
temperature conditions (warmed up or warming up)
as those stored at the time the last test failed.
Meeting these requirements ensures that the fault which
turned on the MIL has been corrected.
The MIL is on the instrument panel and has the following
functions:
It informs the driver that a fault affecting the vehicle’s
emission levels has occurred and that the vehicle
should be taken for service as soon as possible.
As a system check, the MIL will come on with the key
ON and the engine not running. When the engine is
started, the MIL will turn OFF.
When the MIL remains ON while the engine is run-
ning, or when a malfunction is suspected due to a
driveability or emissions problem, an EOBD System
Check must be performed. The procedures for these
checks are given in EOBD System Check. These
checks will expose faults which may not be detected
if other diagnostics are performed first.
Page 112 of 1184
1F–14 ENGINE CONTROLS
DAEWOO M-150 BL2
termittent fault will also be erased from memory. If the
fault that caused the DTC to be stored into memory has
been corrected, the Diagnostic Executive will begin to
count the ‘‘warm-up” cycles with no further faults de-
tected, the DTC will automatically be cleared from the
Engine Control Module (ECM) memory.
To clear DTCs, use the diagnostic scan tool.
It can’t cleared DTCs without the diagnostic scan tool.
So you must use the diagnostic scan tool.
Notice: To prevent system damage, the ignition key
must be OFF when disconnecting or reconnecting bat-
tery power.
The power source to the control module. Examples:
fuse, pigtail at battery ECM connectors, etc.
The negative battery cable. (Disconnecting the nega-
tive battery cable will result in the loss of other Euro
On-Board memory data, such as preset radio tuning.)
DTC Modes
On Euro On-Board Diagnostic (EOBD) passenger cars
there are five options available in the scan tool DTC
mode to display the enhanced information available. A
description of the new modes, DTC Info and Specific
DTC, follows. After selecting DTC, the following menu
appears:
DTC Info.
Specific DTC.
Freeze Frame.
Fail Records (not all applications).
Clear Info.
The following is a brief description of each of the sub
menus in DTC Info and Specific DTC. The order in
which they appear here is alphabetical and not neces-
sarily 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 ser-
vice procedures.
To get a complete description of any status, press the
‘‘Enter” key before pressing the desired F-key. For ex-
ample, pressing ‘‘Enter” then an F-key will display a defi-
nition of the abbreviated scan tool status.
DTC Status
This selection will display any DTCs that have not run
during 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 num-
ber to be removed from the scan tool screen.
Fail This Ign. (Fail This Ignition)
This selection will display all DTCs that have failed dur-
ing 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 B
DTCs that have not requested the Malfunction Indicator
Lamp (MIL). It will display all type A, B and E DTCs that
have requested 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 have failed the
last time the test ran. The last test may have run during
a previous ignition cycle if a type A or type B DTC is dis-
played. For type C and type D DTCs, the last failure
must have occurred 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
using this option. This selection will report type B and E
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 the 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 dis-
played.
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
possible descriptions follow with a brief explanation.
The “F2” key is used, in this mode, to display a descrip-
tion of the DTC. The “Ye s” 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,
Page 150 of 1184
1F–52 ENGINE CONTROLS
DAEWOO M-150 BL2
MAA1F010
DATA LINK CONNECTOR DIAGNOSIS
Circuit Description
The provision for communicating with the Engine Con-
trol Module (ECM) is the Data Link Connector (DLC). It
is located under the instrument panel. The DLC is used
to connect the scan tool. Battery power and ground is
supplied for the scan tool through the DLC. The Key-
word 2000 serial data circuit to the DLC allows the ECM
to communicate with the scan tool. A Universal Asyn-
chronous Receiver Transmitter (UART) serial data line
is used to communicate with the other modules such as
the Electronic Brake Control Module (EBCM), the Sup-
plemental Inflatable Restraint (SIR) system. and the In-
strument Panel Cluster.
Diagnostic Aids
Ensure that the correct application (model line, car year,
etc.) has been selected on the scan tool. If communica-
tion still cannot be established, try the scan tool onanother vehicle to ensure that the scan tool or cables
are not the cause of the condition.
An intermittent may be caused by a poor connection,
rubbed through wire insulation, or a broken wire inside
the insulation.
Any circuitry that is suspected of causing an intermittent
complaint should be thoroughly checked for the follow-
ing conditions:
Backed-out terminals.
Improper mating of terminals.
Broken locks.
Improperly formed or damaged terminals.
Poor terminal-to-wiring connection.
Physical damage to the wiring harness.
Corrosion.
Page 153 of 1184
ENGINE CONTROLS 1F – 55
DAEWOO M-150 BL2
DIAGNOSTIC TROUBLE CODE DIAGNOSIS
CLEARING TROUBLE CODES
Notice: To prevent Engine Control Module (ECM) dam-
age, the key must be OFF when disconnecting or recon-
necting the power to the ECM (for example battery
cable, ECM pigtail connector, ECM fuse, jumper cables,
etc.).When the ECM sets a Diagnostic Trouble Code
(DTC), the Malfunction Indicator Lamp (MIL) lamp will
be turned on only for type A, B and E but a DTC will be
stored in the ECM’s memory for all types of DTC. If theproblem is intermittent, the MIL will go out after 10 sec-
onds if the fault is no longer present. The DTC will stay
in the ECM’s memory until cleared by scan tool. Remov-
ing battery voltage for 10 seconds will clear some stored
DTCs.
DTCs should be cleared after repairs have been com-
pleted. Some diagnostic tables will tell you to clear the
codes before using the chart. This allows the ECM to set
the DTC while going through the chart, which will help to
find the cause of the problem more quickly.
DIAGNOSTIC TROUBLE CODES
DTCFunctionError TypeIlluminate MIL
P0107Manifold Absolute Pressure Sensor Low VoltageAYES
P0108Manifold Absolute Pressure Sensor High voltageAYES
P0112Intake Air Temperature Sensor Low VoltageEYES
P0113Intake Air Temperature Sensor High voltageEYES
P0117Engine Coolant Temperature Sensor Low VoltageAYES
P0118Engine Coolant Temperature Sensor High voltageAYES
P0122Throttle Position Sensor Low VoltageAYES
P0123Throttle Position Sensor Hig voltageAYES
P0131Oxygen Sensor Low VoltageAYES
P0132Oxygen Sensor High VoltageAYES
P0133Oxygen Sensor No ActivityEYES
P0137Heated Oxygen Sensor Low VoltageEYES
P0138Heated Oxygen Sensor high voltageEYES
P0140Heated Oxygen Sensor No ActivityEYES
P0141Heated Oxygen Sensor Heater MalfuctionEYES
P0171Fuel Trim System Too LeanEYES
P0172Fuel Trim System Too RichEYES
P1230Fuel Pump Relay Low VoltageAYES
P1231Fuel Pump Relay High VoltageAYES
P0261Injector 1 Low VoltageAYES
P0262Injector 1 high voltageAYES
P0264Injector 2 Low VoltageAYES
P0265Injector 2 high voltageAYES
P0267Injector 3 Low VoltageAYES
P0268Injector 3 high voltageAYES
P0300Multifle Cylinder MisfireA/EBLINKING/ON
P1320Crankshatft Segment Period Segment Adaptation At LimitEYES
P1321Crankshatft Segment Period Tooth ErrorEYES
P0327Knock Sensor Circuit FaultEYES
P0335Magnetic Crankshaft Position Sensor Electrical ErrorEYES
Page 156 of 1184
1F–58 ENGINE CONTROLS
DAEWOO M-150 BL2
MAA1F060
DIAGNOSTIC TROUBLE CODE (DTC) – P0107
MANIFOLD ABSOLUTE PRESSURE SENSOR LOW VOLTAGE
Circuit Description
The engine control module (ECM) uses the Manifold Ab-
solute Pressure (MAP) sensor to control the fuel deliv-
ery and the ignition timing. The MAP sensor measures
the changes in the intake manifold pressure, which re-
sults from engine load (intake manifold vacuum) and the
rpm changes; and converts these into voltage outputs.
The ECM sends a 5 volt-reference voltage to the MAP
sensor. As the manifold pressure changes, the output
voltage of the MAP sensor also changes. By monitoring
the MAP sensor output voltage, the ECM knows the
manifold pressure. A low-pressure (low voltage) output
voltage will be about 1.0 to 1.5 volts at idle, while higher
pressure (high voltage) output voltage will be about 4.5
to 5.0 at wide open throttle (WOT). The MAP sensor is
metric pressure, allowing the ECM to make adjustments
for different altitudes.
Conditions for Setting the DTC
This DTC can be stored in “key-on” status.
(Case A)
When the engine idling.
No throttle position(TP) sensor fail conditions pres-
ent.
Engine speed(rpm) is less than 2,500rpm.
The MAP is less than 15kPA.
(Case A)
When the engine part load.
The engine revolution speed is less than 4,000rpm.
No Throttle Position (TP) Sensor fails conditions
present.
The Throttle Position (TP) angle greather than 20.0The MAP is less than 15 kPA.
An open or low voltage condition exists.
Action Taken when the DTC Sets
The Malfunction Indicator Lamp (MIL) will illuminate.
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.
A history DTC is stored.
The coolant fan turns ON.
The ECM will substitutes a fixed MAP value and use
TP to control the fuel delivery (the scan tool will not
show defaulted)
Conditions for Clearing the MIL/DTC
The MIL will turn off after four consecutive ignition
cycles in which the diagnostic runs without a fault.
A history DTC will clear after 40 consecutive warm-up
cycles without a fault.
DTC(s) can be cleared by using the scan tool.
Diagnostic Aids
With the ignition ON and the engine stopped, the man-
ifold pressure is equal to atmosphere pressure and the
signal voltage will be high.
The ECM as an indication of vehicle altitude uses this
information. Comparison of this reading with a known
good vehicle with the same sensor is a good way to
check the accuracy of a suspect sensor. Readings
should be the same ±0.4volt.
If a DTC P 0107 is intermittent, refer to “Manifold Abso-
lute Pressure Check” in this Section for further diagno-
sis.
Page 160 of 1184
1F–62 ENGINE CONTROLS
DAEWOO M-150 BL2
MAA1F060
DIAGNOSTIC TROUBLE CODE (DTC) – P0108 MANIFOLD ABSOLUTE
PRESSURE SENSOR HIGH VOLTAGE
Circuit Description
The engine control module (ECM) uses the Manifold Ab-
solute Pressure (MAP) sensor to control the fuel deliv-
ery and the ignition timing. The MAP sensor measures
the changes in the intake manifold pressure, which re-
sults from engine load (intake manifold vacuum) and the
rpm changes; and converts these into voltage outputs.
The ECM sends a 5 volt-reference voltage to the MAP
sensor. As the manifold pressure changes, the output
voltage of the MAP sensor also changes. By monitoring
the MAP sensor output voltage, the ECM knows the
manifold pressure. A low-pressure (low voltage) output
voltage will be about 1.0 to 1.5 volts at idle, while higher
pressure (high voltage) output voltage will be about 4.5
to 4.8 at wide open throttle (WOT). The MAP sensor is
metric pressure, allowing the ECM to make adjustments
for different altitudes.
Conditions for Setting the DTC
This DTC can be stored in “key-on” status.
Engine speed is greater than 2,000rpm.
No throttle position sensor (TPS) fail conditions pres-
ent.
The MAP is greater than 600m bar.
A high voltage condition exists.
Action Taken when the DTC Sets
The Malfunction Indicator Lamp (MIL) will illuminate.
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.A history DTC is stored.
The ECM will substitutes a fixed MAP value and use
TP to control the fuel delivery (the scan tool will not
show defaulted)
Conditions for Clearing the MIL/DTC
The MIL will turn off after four consecutive ignition
cycles in which the diagnostic runs without a fault.
A history DTC will clear after 40 consecutive warm-up
cycles without a fault.
DTC(s) can be cleared by using the scan tool.
Diagnostic Aids
With the ignition ON and the engine stopped, the man-
ifold pressure is equal to atmosphere pressure and the
signal voltage will be high.
The ECM as an indication of vehicle altitude uses this
information. Comparison of this reading with a known
good vehicle with the same sensor is a good way to
check the accuracy of a suspect sensor. Readings
should be the same ±0.4volt.
If a DTC P 0108 is intermittent, refer to “manifold abso-
lute pressure check” in this Section for further diagnosis.
If the connections are OK monitor the manifold absolute
pressure(MAP) sensor signal voltage while moving re-
lated connectors and the wiring harness. If the failure is
induced, the display on the scan tool will change. This
may help to isolate the location of an intermittent mal-
function.
Page 170 of 1184
1F–72 ENGINE CONTROLS
DAEWOO M-150 BL2
MAA1F110
DIAGNOSTIC TROUBLE CODE (DTC) – P0117 ENGINE COOLANT
TEMPERATURE SENSOR LOW VOLTAGE
Circuit Description
The Engine Coolant Temperature sensor (ECT) uses a
thermistor to control the signal voltage to the engine
control module (ECM).
The ECM supplies a voltage on the signal circuit to the
sensor. When the engine coolant is cold, the resistance
is high; therefore the ECT signal voltage will be high.
As the engine warms, the sensor resistance becomes
less, and the voltage drops. At normal engine operating
temperature, the voltage will be between 1.5 and 2.0
volts at the ECT signal terminal.
The ECT sensor is used to the following items:
Fuel delivery.
Lock Up Clutch (LUC).
Ignition.
Evaporator Emission (EVAP) Canister Purge Valve.
Electric cooling fan.
Conditions for Setting the DTC
This DTC can be stored in “key-on” status.
The engine rum time is greater than 3 seconds.
A low voltage condition exits.
ECT voltage is less than 0.03V.
Action Taken when the DTC Sets
The Malfunction Indicator Lamp (MIL) will illuminate.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.
A history DTC is stored.
The coolant fan turns ON.
The ECM will default to 20°C(68°F)for the first 60
seconds of the engine run time, and then
92°C(198°F).
the scan ttol will not show the defaulted value.
Conditions for Clearing the MIL/DTC
The MIL will turn off after four consecutive ignition
cycles in which the diagnostic runs without a fault.
A history DTC will clear after 40 consecutive warm-up
cycles without a fault.
DTC(s) can be cleared by using the scan tool.
Diagnostic Aids
After the engine has started, the ECT should rise steadi-
ly to about 90°C(194°F) then stabilize when the thermo-
stat opens.
Use the temperature vs. resistance values table to eval-
uate the possibility of a skewed sensor. Refer to “Te m -
perature vs. Resistance” in this Section.
Page 172 of 1184
1F–74 ENGINE CONTROLS
DAEWOO M-150 BL2
MAA1F110
DIAGNOSTIC TROUBLE CODE (DTC) – P0118 ENGINE COOLANT
TEMPERATURE SENSOR HIGH VOLTAGE
Circuit Description
The coolant temperature sensor (ECT) uses a thermis-
tor to control the signal voltage to the engine control
module (ECM).
The ECM supplies a voltage on the signal circuit to the
sensor. When the air is cold, the resistance is high;
therefore the ECT sensor signal voltage will be high.
As the engine warms, the sensor resistance becomes
less, and the voltage drops. At normal engine operating
temperature, the voltage will be between 1.5 and 2.0
volts at the ECT sensor signal terminal.
The ECT sensor is used to the following items:
Fuel delivery.
Lock Up Clutch (LUC).
Ignition.
Evaporator Emission (EVAP) Canister Purge Valve.
Idle Air Control (IAC) valve.
Electric cooling fan.
Conditions for Setting the DTC
This DTC can be stored in “key-on” status.
The engine rum time is greater than 3 seconds.
The ECT sensor indicates that the engine coolant
temperature is less than –40°C(–40°F).
ECT voltage is greater than 4.98V.A low voltage condition exits.
Action Taken when the DTC Sets
The Malfunction Indicator Lamp (MIL) will illuminate.
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.
A history DTC is stored.
The coolant fan turns ON.
The ECM will substitutes a fixed MAP value and use
TP to control the fuel delivery (the scan tool will not
show defaulted)
Conditions for Clearing the MIL/DTC
The MIL will turn off after four consecutive ignition
cycles in which the diagnostic runs without a fault.
A history DTC will clear after 40 consecutive warm-up
cycles without a fault.
DTC(s) can be cleared by using the scan tool.
Diagnostic Aids
After the engine has started, the ECT should rise steadi-
ly to about 90°C(194°F) then stabilize when the thermo-
stat opens.
Use the temperature vs. resistance values table to eval-
uate the possibility of a skewed sensor. Refer to “Te m -
perature vs. Resistance” in this Section.
Page 212 of 1184
1F–114 ENGINE CONTROLS
DAEWOO M-150 BL2
MAA1F040
DIAGNOSTIC TROUBLE CODE (DTC) – P1230 FUEL PUMP RELAY LOW
V O LTA G E
Circuit Description
When the ignition switch is turned ON, the ECM will acti-
vate the fuel pump relay and run the in-tank fuel pump.
The fuel pump will operate as long as the engine is
cranking or running and the ECM is receiving ignition
reference pulses.
Conditions for Setting the DTC
This DTC can be stored in “key-on” status.
An open or low voltage condition exists.
Action Taken when the DTC Sets
The Malfunction Indicator Lamp (MIL) will illuminate.
The ECM will record operating conditions at the time
the diagnostic fails. This information will be stored in
the Freeze Frame and Records buffers.
A history DTC is stored.
Coolant fan turns ON.
Conditions for Clearing the MIL/DTC
The MIL will turn off after 4 consecutive ignition
cycles in which the diagnostic runs without a fault.A history DTC will clear after 40 consecutive warm up
cycles without a fault.
DTC(s) can be cleared by using the scan tool.
Diagnostic Aids
An Intermittent problem may be caused by a poor con-
nection, rubbed through wire insulation, or wire that is
broken inside the insulation.
Any circuitry, that is suspected as causing the com-
plaint, should be thoroughly checked for the following
conditions.
Backed-out terminals
Improper mating
Broken locks
Improperly formed
Damaged terminals
Poor terminals to wire connection
Physical damage to the wiring harness