2003 DAEWOO MATIZ coolant

ENGINE CONTROLS 1F–5
DAEWOO M-150 BL2
fuel is delivered under one of several conditions, called
“modes.’’
Starting Mode
When the ignition is turned ON, the ECM turns the fuel
pump relay on for 2 seconds. The fuel pump then builds
fuel pressure. The ECM also checks the Engine Coolant
Temperature (ECT) sensor and the Throttle Position
(TP) sensor and determines the proper air/fuel ratio for
starting the engine. The ECM controls the amount of
fuel delivered in the starting mode by changing how long
the fuel injector is turned on and off. This is done by
“pulsing’’ the fuel injectors for very short times.
Run Mode
The run mode has two conditions called “open loop’’ and
“closed loop.’’
Open Loop
When the engine is first started and it is above 400 rpm,
the system goes into “open loop’’ operation. In “open
loop,’’ the ECM ignores the signal from the O2S and cal-
culates the air/fuel ratio based on inputs from the ECT
sensor and the MAP sensor. The ECM stays in ”open
loop” until the following conditions are met:

The O2S has a varying voltage output, showing that it
is hot enough to operate properly.

The ECT sensor is above a specified temperature.

A specific amount of time has elapsed after starting
the engine.
Closed Loop
The specific values for the above conditions vary with
different engines and are stored in the Electronically
Erasable Programmable Read-Only Memory (EE-
PROM). When these conditions are met, the system
goes into “closed loop” operation. In “closed loop,” the
ECM calculates the air/fuel ratio (fuel injector on-time)
based on the signals from the oxygen sensors. This al-
lows the air/fuel ratio to stay very close to 14.7 to 1.
Acceleration Mode
The ECM responds to rapid changes in throttle position
and airflow and provides extra fuel.
Deceleration Mode
The ECM responds to changes in throttle position and
airflow and reduces the amount of fuel. When decelera-
tion is very fast, the ECM can cut off fuel completely for
short periods of time.
Battery Voltage Correction Mode
When battery voltage is low, the ECM can compensate
for a weak spark delivered by the ignition module by us-
ing the following methods:

Increasing the fuel injector pulse width.

Increasing the idle speed rpm.

Increasing the ignition dwell time.
Fuel Cut-Off Mode
No fuel is delivered by the fuel injectors when the ignition
is off. This prevents dieseling or engine run-on. Also, the
fuel is not delivered if there are no reference pulses re-
ceived from the CKP sensor. This prevents flooding.
EVAPORATIVE EMISSION CONTROL
SYSTEM OPERATION
The basic Evaporative Emission (EVAP) control system
used is the charcoal canister storage method. This
method transfers fuel vapor from the fuel tank to an acti-
vated carbon (charcoal) storage canister which holds
the vapors when the vehicle is not operating. When the
engine is running, the fuel vapor is purged from the car-
bon element by intake airflow and consumed in the nor-
mal combustion process.
Gasoline vapors from the fuel tank flow into the tube la-
beled TANK. These vapors are absorbed into the car-
bon. The canister is purged by Engine Control Module
(ECM) when the engine has been running for a specified
amount of time. Air is drawn into the canister and mixed
with the vapor. This mixture is then drawn into the intake
manifold.
The ECM supplies a ground to energize the controlled
charcoal canister purge solenoid valve. This valve is
Pulse Width Modulated (PWM) or turned on and off sev-
eral times a second. The controlled charcoal canister
purge PWM duty cycle varies according to operating
conditions determined by mass airflow, fuel trim, and in-
take air temperature.
Poor idle, stalling, and poor driveability can be caused
by the following conditions:

An inoperative controlled canister purge valve.

A damaged canister.

Hoses that are split, cracked, or not connected to the
proper tubes.
CONTROLLED CHARCOAL
CANISTER
The controlled charcoal canister is an emission control
device containing activated charcoal granules. The con-
trolled charcoal canister is used to store fuel vapors from
the fuel tank. Once certain conditions are met, the En-
gine Control Module (ECM) activates the controlled
charcoal canister purge solenoid, allowing the fuel va-
pors to be drawn into the engine cylinders and burned.
POSITIVE CRANKCASE
VENTILATION CONTROL SYSTEM
OPERATION
A Positive Crankcase Ventilation (PCV) control system
is used to provide complete use of the crankcase va-

1F–6 ENGINE CONTROLS
DAEWOO M-150 BL2
pors. Fresh air from the air cleaner is supplied to the
crankcase. The fresh air is mixed with blowby gases
which then pass through a vacuum hose into the intake
manifold.
Periodically inspect the hoses and the clamps. Replace
any crankcase ventilation components as required.
A restricted or plugged PCV hose may cause the follow-
ing conditions:

Rough idle

Stalling or low idle speed

Oil leaks

Oil in the air cleaner

Sludge in the engine
A leaking PCV hose may cause the following conditions:

Rough idle

Stalling

High idle speed
ENGINE COOLANT TEMPERATURE
SENSOR
The Engine Coolant Temperature (ECT) sensor is a
thermistor (a resistor which changes value based on
temperature) mounted in the engine coolant stream.
Low coolant temperature produces a high resistance
(100,000 ohms at –40C [–40F]) while high tempera-
ture causes low resistance (70 ohms at 130C [266F]).
The Engine Control Module (ECM) supplies 5 volts to
the ECT sensor through a resistor in the ECM and mea-
sures the change in voltage. The voltage will be high
when the engine is cold and low when the engine is hot.
By measuring the change in voltage, the ECM can de-
termine the coolant temperature. The engine coolant
temperature affects most of the systems that the ECM
controls. A failure in the ECT sensor circuit should set a
Diagnostic Trouble Code (DTC) P0117 or P0118. Re-
member, these DTC indicate a failure in the ECT circuit,
so proper use of the chart will lead either to repairing a
wiring problem or to replacing the sensor to repair a
problem properly.
THROTTLE POSITION SENSOR
The Throttle Position (TP) sensor is a potentiometer
connected to the throttle shaft of the throttle body. The
TP sensor electrical circuit consists of a 5-volt supply
line and a ground line, both provided by the Engine Con-
trol Module (ECM). The ECM calculates the throttle
position by monitoring the voltage on this signal line. The
TP sensor output changes as the accelerator pedal is
moved, changing the throttle valve angle. At a closed
throttle position, the output of the TP sensor is low,
about 0.4–0.8 volt. As the throttle valve opens, the out-
put increases so that, at Wide Open Throttle (WOT), the
output voltage will be about 4.5–5 volts.The ECM can determine fuel delivery based on throttle
valve angle (driver demand). A broken or loose TP sen-
sor can cause intermittent bursts of fuel from the injector
and an unstable idle, because the ECM thinks the
throttle is moving. A problem in any of the TP sensor cir-
cuits should set a Diagnostic Trouble Code (DTC)
P0122 or P0123. Once the DTC is set, the ECM will sub-
stitute a default value for the TP sensor and some ve-
hicle performance will return.
CATALYST MONITOR OXYGEN
SENSORS
Three-way catalytic converters are used to control emis-
sions of hydrocarbons (HC), carbon monoxide (CO),
and oxides of nitrogen (NOx). The catalyst within the
converters promotes a chemical reaction. This reaction
oxidizes the HC and CO present in the exhaust gas and
converts them into harmless water vapor and carbon
dioxide. The catalyst also reduces NOx by converting it
to nitrogen. The ECM can monitor this process using the
oxygen sensor (O2S) and heated oxygen sensor
(HO2S). These sensors produce an output signal which
indicates the amount of oxygen present in the exhaust
gas entering and leaving the three-way converter. This
indicates the catalyst’s ability to efficiently convert ex-
haust gasses. If the catalyst is operating efficiently, the
O2S signals will be more active than the signals pro-
duced by the HO2S. The catalyst monitor sensors oper-
ate the same way as the fuel control sensors. The
sensors’ main function is catalyst monitoring, but they
also have a limited role in fuel control. If a sensor output
indicates a voltage either above or below the 450 mV
bias voltage for an extended period of time, the Engine
Control Module (ECM) will make a slight adjustment to
fuel trim to ensure that fuel delivery is correct for catalyst
monitoring.
A problem with the O2S circuit will set DTC P0131,
P0132, P0133 or P0134 depending on the special condi-
tion. A problem with the HO2S signal will set DTC
P0137, P0138, P0140 or P0141 depending on the spe-
cial condition.
A fault in the heated oxygen sensor (HO2S) heater ele-
ment or its ignition feed or ground will result in lower oxy-
gen sensor response. This may cause incorrect catalyst
monitor diagnostic results.
ELECTRIC EXHAUST GAS
RECIRCULATION VALVE
The Electric Exhaust Gas Recirculation (EEGR) system
is used on engines equipped with an automatic trans-
axle to lower oxides of nitrogen (NOx) emission levels
caused by high combustion temperature. The main ele-
ment of the system is the EEGR valve, controlled electri-
cally by the Engine Control Module (ECM). The EEGR
valve feeds small amounts of exhaust gas into the intake

ENGINE CONTROLS 1F–7
DAEWOO M-150 BL2
manifold to decrease combustion temperature. The
amount of exhaust gas recirculated is controlled by vari-
ations in vacuum and exhaust back pressure. If too
much exhaust gas enters, combustion will not take
place. For this reason, very little exhaust gas is allowed
to pass through the valve, especially at idle.
The EEGR valve is usually open under the following
conditions:

Warm engine operation.

Above idle speed.
Results of Incorrect Operation
Too much EEGR flow tends to weaken combustion,
causing the engine to run roughly or to stop. With too
much EEGR flow at idle, cruise, or cold operation, any of
the following conditions may occur:

The engine stops after a cold start.

The engine stops at idle after deceleration.

The vehicle surges during cruise.

Rough idle.
If the EEGR valve stays open all the time, the engine
may not idle. Too little or no EEGR flow allows combus-
tion temperatures to get too high during acceleration
and load conditions. This could cause the following con-
ditions:

Spark knock (detonation)

Engine overheating

Emission test failure
INTAKE AIR TEMPERATURE
SENSOR
The Intake Air Temperature (IAT) sensor is a thermistor,
a resistor which changes value based on the tempera-
ture of the air entering the engine. Low temperature pro-
duces a high resistance (100 kohms at –40C [–40F]),
while high temperature causes a low resistance (70
ohms at 130C [266F]).
The Engine Control Module (ECM) provides 5 volts to
the IAT sensor through a resistor in the ECM and mea-
sures the change in voltage to determine the IAT. The
voltage will be high when the manifold air is cold and low
when the air is hot. The ECM knows the intake IAT by
measuring the voltage.
The IAT sensor is also used to control spark timing when
the manifold air is cold.
A failure in the IAT sensor circuit sets a diagnostic
trouble code P0112 or P0113.
IDLE AIR CONTROL VALVE
Notice: Do not attempt to remove the protective cap
and readjust the stop screw. Misadjustment may result
in damage to the Idle Air Control (IAC) valve or to the
throttle body.The IAC valve is mounted on the throttle body where it
controls the engine idle speed under the command of
the Engine Control Module (ECM). The ECM sends volt-
age pulses to the IAC valve motor windings, causing the
IAC valve pintle to move in or out a given distance (a
step or count) for each pulse. The pintle movement con-
trols the airflow around the throttle valves which, in turn,
control the engine idle speed.
The desired idle speeds for all engine operating condi-
tions are programmed into the calibration of the ECM.
These programmed engine speeds are based on the
coolant temperature, the park/neutral position switch
status, the vehicle speed, the battery voltage, and the
A/C system pressure, if equipped.
The ECM “learns” the proper IAC valve positions to
achieve warm, stabilized idle speeds (rpm) desired for
the various conditions (park/neutral or drive, A/C on or
off, if equipped). This information is stored in ECM ”keep
alive” memories (information is retained after the ignition
is turned off). All other IAC valve positioning is calcu-
lated based on these memory values. As a result, en-
gine variations due to wear and variations in the
minimum throttle valve position (within limits) do not af-
fect engine idle speeds. This system provides correct
idle control under all conditions. This also means that
disconnecting power to the ECM can result in incorrect
idle control or the necessity to partially press the accel-
erator when starting until the ECM relearns idle control.
Engine idle speed is a function of total airflow into the
engine based on the IAC valve pintle position, the
throttle valve opening, and the calibrated vacuum loss
through accessories. The minimum throttle valve posi-
tion is set at the factory with a stop screw. This setting
allows enough airflow by the throttle valve to cause the
IAC valve pintle to be positioned a calibrated number of
steps (counts) from the seat during “controlled” idle op-
eration. The minimum throttle valve position setting on
this engine should not be considered the “minimum idle
speed,” as on other fuel injected engines. The throttle
stop screw is covered with a plug at the factory following
adjustment.
If the IAC valve is suspected as being the cause of im-
proper idle speed, refer to “Idle Air Control System
Check” in this section.
MANIFOLD ABSOLUTE PRESSURE
SENSOR
The Manifold Absolute Pressure (MAP) sensor mea-
sures the changes in the intake manifold pressure which
result from engine load and speed changes and con-
verts these to a voltage output.
A closed throttle on engine coast down produces a rela-
tively low MAP output. MAP is the opposite of vacuum.
When manifold pressure is high, vacuum is low. The
MAP sensor is also used to measure barometric pres-
sure. This is performed as part of MAP sensor calcula-

ENGINE CONTROLS 1F–11
DAEWOO M-150 BL2

The fault identified by the diagnostic test is currently
active.

The fault has been active during this ignition cycle.

The operating conditions at the time of the failure.
Remember, a fuel trim Diagnostic Trouble Code (DTC)
may be triggered by a list of vehicle faults. Make use of
all information available (other DTCs stored, rich or lean
condition, etc.) when diagnosing a fuel trim fault.
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 check-
ing. 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 Pres-
sure (MAP) voltage. Input components may include, but
are not limited to, the following sensors:

Vehicle Speed Sensor (VSS).

Crankshaft Position (CKP) sensor.

Throttle Position (TP) sensor.

Engine Coolant Temperature (ECT) sensor.

Camshaft Position (CMP) sensor.

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 func-
tional monitoring is not feasible will be monitored for cir-
cuit continuity and out-of-range values if applicable.
Output components to be monitored include, but are not
limited to the following circuit:

Idle Air Control (IAC) Motor.

Controlled Canister Purge Valve.

A/C relays.

Cooling fan relay.

VSS output.

Malfunction Indicator Lamp (MIL) control.
Refer to “Engine Control Module” and the sections on
Sensors in General Descriptions.
Passive and Active Diagnostic Tests
A passive test is a diagnostic test which simply monitors
a vehicle system or component. Conversely, an activetest, actually takes some sort of action when performing
diagnostic functions, often in response to a failed pas-
sive test. For example, the Electric Exhaust Gas Recir-
culation (EEGR) diagnostic active test will force the
EEGR valve open during closed throttle deceleration
and/or force the EEGR valve closed during a steady
state. Either action should result in a change in manifold
pressure.
Intrusive Diagnostic Tests
This is any Euro On-Board test run by the Diagnostic
Management System which may have an effect on ve-
hicle performance or emission levels.
Warm-Up Cycle
A warm-up cycle means that engine at temperature
must reach a minimum of 70C (160F) and rise at least
22C (40F) 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 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
vehicle information as does Freeze Frame, but it will
store that information for any fault which is stored in
Euro On-Board memory, while Freeze Frame stores in-
formation 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
Euro On-Board test run by the vehicle’s Diagnostic Man-
agement System. A diagnostic is simply a test run on a
system or component to determine if the system or com-
ponent is operating according to specification. There are
many diagnostics, shown in the following list:

Misfire.

Oxygen sensors (O2S)

Heated oxygen sensor (HO2S)

Electric Exhaust Gas Recirculation (EEGR)

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.”

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.

1F–22 ENGINE CONTROLS
DAEWOO M-150 BL2
Multiple ECM Information Sensor DTCs Set
StepActionValue(s)YesNo
1
Perform an Euro On-Board Diagnostic (EOBD)
System Check.
Is the check complete.
–
Go to Step 2
Go to “Euro
On-Board
Diagnostic
System Check”
2
1. Turn the ignition OFF and disconnect the Engine
Control Module (ECM).
2. Turn the ignition ON and check the 5 volt
reference circuit for the following conditions:

Poor connection at the ECM.

Open between the ECM connector affected
sensors shorted to ground or voltage.
3. If a problem is found, locate and repair the open
or short circuit as necessary.
Is a problem found?
–
Go to Step 19Go to Step 3
3
1. Check the sensor ground circuit for the following
conditions:

Poor connection at the ECM or affected
sensors.

Open between the ECM connector and the
affected sensors.
2. If a problem is found, repair it as necessary.
Is a problem found?
–
Go to Step 19Go to Step 4
4
Measure the voltage of the Electric Exhaust Gas
Recirculation (EEGR) Pintle Position Sensor signal
circuit between ECM harness connector and ground.
Does the voltage measure near the specified value?
0 VGo to Step 5Go to Step 9
5
Measure the voltage of the Manifold Absolute
Pressure (MAP) sensor signal circuit between the
ECM harness connector and ground.
Does the voltage measure near the specified value?
0 VGo to Step 6Go to Step 11
6
Measure the voltage of the Throttle Position (TP)
sensor signal circuit between the ECM harness
connector and ground.
Does the voltage measure near the specified value?
0 VGo to Step 7Go to Step 12
7
Measure the voltage of the Intake Air Temperature
(IAT) sensor signal circuit between the ECM harness
connector and ground.
Does the voltage measure near the specified value?
0 VGo to Step 8Go to Step 13
8
Measure the voltage of the Engine Coolant
Temperature (ECT) sensor signal circuit between the
ECM harness connector and ground.
Does the voltage measure near the specified value?
0 VGo to Step 16Go to Step 14
9
1. Disconnect the EEGR valve.
2. Measure the voltage of the EEGR Pintle Position
sensor signal circuit between the ECM harness
connector and ground.
Does the voltage measure near the specified value?
0 VGo to Step 10Go to Step 15
10Replace the EEGR valve.
Is the repair complete?–Go to Step 19–
11
Locate and repair the short to voltage in the MAP
sensor signal circuit.
Is the repair complete?
–
Go to Step 19
–

1F–42 ENGINE CONTROLS
DAEWOO M-150 BL2
MAA1F070
IDLE AIR CONTROL SYSTEM CHECK
Circuit Description
The Engine Control Module (ECM) controls the engine
idle speed with the Idle Air Control (IAC) valve. To in-
crease the idle speed, the ECM pulls the IAC pintle
away from its seat, allowing more air to pass by the
throttle body. To decrease the idle speed, it extends the
IAC valve pintle toward its seat, reducing bypass air
flow. A scan tool will read the ECM commands to the
IAC valve in counts. The higher counts indicate more air
bypass (higher idle). The lower counts indicate less air is
allowed to bypass (lower idle).
Diagnostic Aids
If the idle is too high, stop the engine. Fully extend the
Idle Air Control (IAC) valve with a IAC driver. Start the
engine. If the idle speed is above 950 rpm, locate and
repair the vacuum leak. Also, check for a binding throttle
plate or throttle linkage or an incorrect base idle setting.
Idle Air Control Valve Reset Procedure
Whenever the battery cable or the Engine Control Mod-
ule (ECM) connector or the ECM fuse EF6 is discon-nected or replaced, the following idle learn procedure
must be performed:
1. Turn the ignition ON for 5 seconds.
2. Turn the ignition OFF for 10 seconds.
3. Turn the ignition ON for 5 seconds.
4. Start the engine in park/neutral.
5. Allow the engine to run until the engine coolant is
above 85C (185F ).
6. Turn the A/C ON for 10 seconds, if equipped.
7. Turn the A/C OFF for 10 seconds, if equipped.
8. If the vehicle is equipped with an automatic trans-
axle, apply the parking brake. While pressing the
brake pedal, place the transaxle in D (drive).
9. Turn the A/C ON for 10 seconds, if equipped.
10. Turn the A/C OFF for 10 seconds, if equipped.
11. Turn the ignition OFF. The idle learn procedure is
complete.

1F–48 ENGINE CONTROLS
DAEWOO M-150 BL2
MAA1F090
ENGINE COOLING FAN CIRCUIT CHECK
Circuit Description
The engine cooling fan circuit operates the cooling fan.
The cooling fan is controlled by the engine control mod-
ule (ECM) based on input from the coolant temperature
sensor (CTS) and the A/C ON/OFF. The ECM controls
the low speed cooling fan operation by internally ground-
ing the ECM connector terminal 39. This energizes the
low speed cooling fan relay and operates the cooling fan
at low speed. The low speed cooling fan operation is
achieved by the cooling fan resistor causing a drop in
the voltage supplied to the cooling fan. The ECM con-
trols the high speed cooling fan operation by internally
grounding the ECM connector terminal 5. This ener-
gizes the high speed cooling fan relay, bypassing the ra-
diator fan resistor. This results in high speed cooling fan
operation.
Diagnostic Aids

If the owner complained of an overheating problem, it
must be determined if the complaint was due to anactual boil over, or the engine coolant temperature
gauge indicated overheating. If the engine is over-
heating and the cooling fans are on, the cooling sys-
tem should be checked.

If the engine fuse block fuse EF15 become open
(blown) immediately after installation, inspect for a
short to ground in the wiring of the appropriate circuit.
If the fuse become open (blown) when the cooling
fans are to be turned on by the Engine Control Mod-
ule (ECM), suspect a faulty cooling fan motor.

The ECM will turn the cooling fan on at low speed
when the coolant temperature is 93C (199F). The
ECM will turn the cooling fans off when the coolant
temperature is 90C (194F).

The ECM will turn the cooling fans on at high speed
when the coolant temperature is 100C (212F). The
ECM will change the cooling fans from high speed to
low speed when the coolant temperature is 97C
(207F).