Resistance vs temperature DAEWOO LACETTI 2004 Service Repair Manual

SECTION : 1F
ENGINE CONTROLS
CAUTION : Disconnect the negative battery cable before removing or installing any electrical unit o r w hen a
tool or equipment could easily come in contact with exposed electrical terminals. Disconnecting this cable will
help prevent personal injury and damage to the vehicle. The ignition must also be in LOCK unless otherwise
noted.
TABLE OF CONTENTS
SPECIFICATIONS1F–6 . . . . . . . . . . . . . . . . . . . . . . . . . .
Engine Data Display Tables 1F–6. . . . . . . . . . . . . . . . .
Engine Data Display Table Definitions 1F–7. . . . . . . .
Fastener Tightening Specifications 1F–10. . . . . . . . .
Fuel System Specifications 1F–11. . . . . . . . . . . . . . . . .
Temperature Vs Resistance 1F–11. . . . . . . . . . . . . . . .
SCHEMATIC AND ROUTING DIAGRAMS1F–12 . . . .
ECM Wiring Diagram
(1.4L/1.6L DOHC – 1 OF 6) 1F–12. . . . . . . . . . . . . .
ECM Wiring Diagram
(1.4L/1.6L DOHC – 2 OF 6) 1F–13. . . . . . . . . . . . . .
ECM Wiring Diagram
(1.4L/1.6L DOHC – 3 OF 6) 1F–14. . . . . . . . . . . . . .
ECM Wiring Diagram
(1.4L/1.6L DOHC – 4 OF 6) 1F–15. . . . . . . . . . . . . .
ECM Wiring Diagram
(1.4L/1.6L DOHC – 5 OF 6) 1F–16. . . . . . . . . . . . . .
ECM Wiring Diagram
(1.4L/1.6L DOHC – 6 OF 6) 1F–17. . . . . . . . . . . . . .
ECM Wiring Diagram (1.8L DOHC – 1 OF 6) 1F–18.
ECM Wiring Diagram (1.8L DOHC – 2 OF 6) 1F–19.
ECM Wiring Diagram (1.8L DOHC – 3 OF 6) 1F–20.
ECM Wiring Diagram (1.8L DOHC – 4 OF 6) 1F–21.
ECM Wiring Diagram (1.8L DOHC – 5 OF 6) 1F–22.
ECM Wiring Diagram (1.8L DOHC – 6 OF 6) 1F–23.
Connector End View 1F–24. . . . . . . . . . . . . . . . . . . . . .
COMPONENT LOCATOR1F–28 . . . . . . . . . . . . . . . . . . .
Component Locator (1.4L/1.6L DOHC) 1F–28. . . . . .
Component Locator (1.8L DOHC) 1F–29. . . . . . . . . . .
DIAGNOSIS1F–30 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SYSTEM DIAGNOSIS 1F–30. . . . . . . . . . . . . . . . . . . . . .
Diagnostic Aids 1F–30. . . . . . . . . . . . . . . . . . . . . . . . . . .
Idle Learn Procedure 1F–30. . . . . . . . . . . . . . . . . . . . . .
TEC (Tooth Error Correction) Learn Procedure 1F–31ON–Board Diagnostic (EOBD) System Check
(1.4L/1.6L DOHC) 1F–32. . . . . . . . . . . . . . . . . . . . . . .
ON–Board Diagnostic (EOBD) System Check
(1.8L DOHC) 1F–34. . . . . . . . . . . . . . . . . . . . . . . . . . .
Multiple ECM Informationn Sensor Dtcs Set 1F–36. .
Engine Cranks But Will Not Run
(1.4L/1.6L DOHC) 1F–40. . . . . . . . . . . . . . . . . . . . . . .
Engine Cranks But Will Not Run (1.8L DOHC) 1F–47
No Malfunction Indicator Lamp (
1.4L/1.6L DOHC) 1F–54. . . . . . . . . . . . . . . . . . . . . . .
No Malfunction Indicator Lamp (1.8L DOHC) 1F–56.
Malfunction Indicator Lamp On Steady (1.4L/1.6L
DOHC) 1F–58. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Malfunction Indicator Lamp On Steady
(1.8L DOHC) 1F–60. . . . . . . . . . . . . . . . . . . . . . . . . . .
Fuel System Diagnosis 1F–62. . . . . . . . . . . . . . . . . . . .
Fuel Pump Relay Circuit Check
(1.4L/1.6L DOHC) 1F–65. . . . . . . . . . . . . . . . . . . . . . .
Fuel Pump Relay Circuit Check (1.8L DOHC) 1F–68.
Main Relay Circuit Check (1.4L/1.6L DOHC) 1F–71.
Main Relay Circuit Check (1.8L DOHC) 1F–73. . . . . .
Manifold Absolute Pressure Check
(1.4L/1.6L DOHC) 1F–75. . . . . . . . . . . . . . . . . . . . . . .
Manifold Absolute Pressure Check
(1.8L DOHC) 1F–77. . . . . . . . . . . . . . . . . . . . . . . . . . .
Idle Air Control System Check
(1.4L/1.6L DOHC) 1F–79. . . . . . . . . . . . . . . . . . . . . . .
Idle Air Control System Check (1.8L DOHC) 1F–82. .
Ignition System Check (1.4L/1.6L DOHC) 1F–85. . . .
Ignition System Check (1.8L DOHC) 1F–88. . . . . . . .
Engine Cooling Fan Circuit Check – Dual Fan
(1.4L/1.6L DOHC) 1F–93. . . . . . . . . . . . . . . . . . . . . . .
Engine Cooling Fan Circuit Check – Dual Fan
(1.8L DOHC) 1F–100. . . . . . . . . . . . . . . . . . . . . . . . . .
Data Link Connector Diagnosis
(1.4L/1.6L DOHC) 1F–106. . . . . . . . . . . . . . . . . . . . . .
Data Link Connector Diagnosis (1.8L DOHC) 1F–108
Fuel Injector Balance Test 1F–110. . . . . . . . . . . . . . . .

ENGINE CONTROLS 1F – 7
DAEWOO V–121 BL4
Parameter ValueScaling
A/C RequestYes/NoNo
A/C ClutchOn/OffOff
Fuel Pump CommandOn/OffOn
Closed LoopYes/NoYe s
Throttle At IdleYes/NoNo
O2 Ready (B1–S1)Yes/NoYe s
Knock PresentYes/NoNo
Fan LowOn/OffOn/Off
Fan HighOn/OffOn/Off
TCC Engaged (Only AT)Yes/NoYe s
Park/Neutral (Only AT)P/N and R/N/DP/N
Fuel Level InputVvaries
Fuel Level Output%varies
Fuel Trim Cell–18
G–SensorV1.1 – 3.7 V (Non–ABS Only)
Engine RuntimeHH:MM:SSHours:Minutes:Seconds
* Condition: Warmed up, idle, park or neutral, A/C off
ENGINE DATA DISPLAY TABLE
DEFINITIONS
ECM Data Description
The following information will assist in diagnosing emis-
sion or driveability problems. A first technician can view
the displays while the vehicle is being driven by second
technician. Refer to Powertrain On–Board Diagnostic
(EOBD) System Check for addition information.
A/C Clutch
The A/C Relay represents the commanded state of the
A/C clutch control relay. The A/C clutch should be en-
gaged when the scan tool displays ON.
A/C Pressure
The A/C High Side displays the pressure value of the A/C
refrigerant pressure sensor. The A/C High Side helps to
diagnose the diagnostic trouble code (DTC) P0533.
A/C Request
The A/C Request represents whether the air conditioning
is being requested from the HVAC selector. The input is re-
ceived by the instrument panel cluster and then sent serial
data to the ECM and finally to the scan tool over KWP 2000
serial data.
Air Fuel Ratio
The Air Fuel Ration indicates the air to fuel ratio based on
the Front Heated Oxygen Sensor (HO2S1) inputs. The
ECM uses the fuel trims to adjust fueling in order to at-
tempt to maintain an air fuel ratio of 14.7:1.BARO
The Barometric Pressure (BARO) sensor measures the
change in the intake manifold pressure which results from
altitude changes. This value is updated at ignition ON and
also at Wide Open Throttle (WOT).
Base Injection PWM
Indicates the base Pulse Width Modulation (PWM) or ON
time of the indicated cylinder injector in milliseconds.
When the engine load is increased, the injector pulse width
will increase.
Calculated Air Flow
The calculated air flow is a calculation based on manifold
absolute pressure. The calculation is used in several diag-
nostics to determine when to run the diagnostics.
Desired Idle Speed
The ECM commands the idle speed. The ECM compen-
sates for various engine loads in order to maintain the de-
sired idle speed. The actual engine speed should remain
close to the desired idle under the various engine loads
with the engine idling.
Engine Coolant Temperature
The Engine Coolant Temperature (ECT) sensor sends en-
gine temperature information to the ECM. The ECM sup-
plies 5 volts to the engine coolant temperature sensor cir-
cuit. The sensor is a thermistor which changes internal
resistance as temperature changes. When the sensor is
cold (internal resistance high), the ECM monitors a high
voltage which it interprets as a cold engine. As the sensor
warms (internal resistance decreases), the voltage signal
will decrease and the ECM will interpret the lower voltage
as a warm engine.

1F – 8IENGINE CONTROLS
DAEWOO V–121 BL4
EGR Desired Position
The desired exhaust gas recirculation (EGR) position is
the commanded EGR position. The ECM calculates the
desired EGR position. The higher the percentage, the lon-
ger the ECM is commanding the EGR valve ON.
Engine Load
Indicates engine load based on manifold absolute pres-
sure. The higher the percentage, the more load the engine
is under.
Engine Run Time
The engine run time is a measure of how long the engine
has been running. When the engine stops running, the tim-
er resets to zero.
Engine Speed
Engine Speed is computed by the ECM from the fuel con-
trol reference input. It should remain close to desired idle
under the various engine loads with the engine idling.
Fan
The Fan Control (FC) Relay is commanded by the ECM.
The FC Relay displays the command as ON or OFF.
Fuel Level Sensor
The Fuel Level Sensor monitors the fuel level in the tank.
The Fuel Level Sensor monitors the rate of change of the
air pressure in the EVAP system. Several of the Enhanced
EVAP System diagnostics are dependent upon the correct
fuel level.
Fuel System Status
The Closed Loop is displayed indicating that the ECM is
controlling the fuel delivery according to the Front Heated
Oxygen Sensor (HO2S1) voltage as close to an air/fuel ra-
tio of 14.7 to 1 as possible.
IAC Position
The scan tool displays the ECM command for the Idle Air
Control (IAC) pintle position in counts. The higher the
number of counts, the greater the commanded idle speed
reads. The Idle Air Control responds to changes in the en-
gine load in order to maintain the desired idle rpm.
Ignition 1 (Voltage)
The ignition volts represent the system voltage measured
by the ECM at the ignition feed circuit.
Intake Air Temperature
The ECM converts the resistance of the Intake Air Tem-
perature (IAT) sensor to degrees in the same manner as
the engine coolant temperature (ECT) sensor. In take air
temperature is used by the ECM to adjust fuel delivery and
spark timing according to incoming air density.Knock Present
The KS Noise Channel indicates when the ECM detects
the KS signal. The ECM should display NO at idle.
Long Term FT
The Long Term Fuel Trim (FT) is derived from the short
term fuel trim value. The Long Term FT is used for the long
term correction of the fuel delivery. A value of 128 counts
(0%) indicates that the fuel delivery requires no com-
pensation in order to maintain a 14.7:1 air to fuel ratio. A
value below 128 counts means that the fuel system is too
rich and the fuel delivery is being reduced. The ECM is de-
creasing the injector pulse width. A value above 128
counts indicates that a lean condition exists for which the
ECM is compensating.
MAP
The Manifold Absolute Pressure (MAP) sensor measures
the change in the intake manifold pressure which results
from engine load and speed changes. As the intake man-
ifold pressure increases, the air density in the intake also
increases and the additional fuel is required.
Misfire History #1–4
Indicates the number of misfires that have occurred after
195 current misfires have been counted. The current mis-
fire counter will add its misfires to the history misfire count-
er after 195 total misfires have taken place. If 1 cylinder is
misfiring, the misfiring current counter will have 195 mis-
fires counted before adding to its history counter. If 2 cylin-
ders are misfiring, the misfiring current counter will add to
their history counters after 97 misfires. The counter incre-
ments only after a misfire diagnostic trouble code (DTC)
has been set.
Front Heated Oxygen Sensor
The pre–converter Front Heated Oxygen Sensor
(HO2S1) reading represents the exhaust oxygen sensor
output voltage. This voltage will fluctuate constantly be-
tween 100 mv (lean exhaust) and 900 mv (rich exhaust)
when the system is operating in a Closed Loop.
Rear Heated Oxygen Sensor
The post–converter Rear Heated Oxygen Sensor
(HO2S2) represents the exhaust oxygen output voltage
past the catalytic converter. This voltage remains inactive,
or the voltage will appear lazy within a range of 100 mv
(lean exhaust) and 900 mv (rich exhaust) when operating
in a Closed Loop.
Short Term FT
The Short Term FT represents a short term correction to
fuel delivery by the ECM in response to the amount of time
the oxygen sensor voltage spends above or below the 450
mv threshold. If the oxygen sensor has mainly been below
450 mv, indicating a lean air/fuel mixture, short term fuel
trim will increase to tell the ECM to add fuel. If the oxygen
sensor voltage stays mainly above the threshold, the ECM
will reduce fuel delivery to compensate for the indicated
rich condition.

ENGINE CONTROLS 1F – 11
DAEWOO V–121 BL4
FUEL SYSTEM SPECIFICATIONS
Gasoline
All engines are designed to use unleaded fuel only. Un-
leaded fuel must be used for proper emission control sys-
tem operation. Its use will also minimize spark plug fouling
and extend engine oil life. Using leaded fuel can damage
the emission warranty coverage. The fuel should meet
specification ASTM D4814 for the U.S. or CGSB 3.5 M93
for Canada. All engines are designed to use unleaded fuel
with a minimum U(R+M)/2e (pump) octane number of 87,
where R=research octane number, and M=motor octane
number.
Ethanol
You may use fuel containing ethanol (ethyl alcohol) orgrain alcohol providing that there is no more than 10 per-
cent ethyl alcohol by volume.
Methanol
Do not use fuels containing methanol. Methanol can cor-
rode metal parts and cause damage to plastic and rubber
parts in the fuel system.
Methyl Tertiary–Butyl Ether (MTBE)
You may use fuel containing Methyl Tertiary–Butyl Ether
(MTBE) providing there is no more than 15 percent MTBE
by volume.
TEMPERATURE VS RESISTANCE
°C°FECT SensorIAT Sensor
OHMS
Temperature vs Resistance Values (Approximate)
100212177187
90194241246
80176332327
70158467441
60140667603
50122973837
4511 31188991
4010414591180
359518021412
308622381700
257727962055
206835202500
155944503055
105056703760
54172804651
03294205800
–523123007273
–1014161809200
–155214509200
–20–42868015080
–30–225270025600
–40–4010070045300

1F – 44IENGINE CONTROLS
DAEWOO V–121 BL4
StepNo Yes Value(s) Action
39Repair the open or short circuit the following termi-
nals.
S Terminal 6 of ECM and terminal 86 of fuel
pump relay.
S Terminal 87 of fuel pump relay and terminal
3 of fuel pump.
Is the repair complete?–Go to Step 2–
40Replace the fuel pump relay.
Is the repair complete?–Go to Step 2–
411. Turn the ignition OFF.
2. Disconnect the fuel inject harness connectors
from all of the fuel injectors.
3. Turn the ignition ON.
4. Connect test light between fuel injector harness
connector 2 and ground.
5. Repeat step 4 for each of the remaining fuel
injectors.
Does the test light on at all of the fuel injectors?–Go to Step 42Go to Step 45
421. Turn the ignition OFF.
2. Connect test light between fuel injector harness
connector 1 and battery positive.
3. Crank the engine.
4. Repeat step 2 and 3 for each of the remaining
fuel injectors.
Does the test light flash for all of the fuel injectors?–Go to Step 43Go to Step 46
43Measure the resistance of each fuel injectors.
Is the resistance within the value specified.
Notice : the resistance will increase slightly at higher
temperature.11.6–12.4WSystem OKGo to Step 44
44Replace any of the fuel injectors with a resistance
out of specification.
Is the repair complete?–Go to Step 2–
451. Inspect the fuse EF22 in engine fuse block.
2. Check for an open between the circuit from
terminal 2 of the four fuel injectors and terminal
87 of main relay.
Is the problem found?–Go to Step 48Go to
”Main Relay
Circuit Check”
46Measure the resistance between following termi-
nals.
S Terminal 2 of injector 1 connector and terminal
59 of ECM connector.
S Terminal 2 of injector 2 connector and terminal
90 of ECM connector.
S Terminal 2 of injector 3 connector and terminal
60 of ECM connector.
S Terminal 2 of injector 4 connector and terminal
89 of ECM connector.
Does the resistance within the specified value?0 WGo to Step 49Go to Step 47
47Repair the open fuel injector harness wire(s).
Is the repair complete?–Go to Step 2–

1F – 48IENGINE CONTROLS
DAEWOO V–121 BL4
StepNo Yes Value(s) Action
11Compare the Engine Coolant Temperature (ECT)
with the Intake Air Temperature (IAT).
Is the ECT relatively close to the IAT?–Go to Step 12Go to ”DTC
P0118 Engine
Coolant Tem-
perature High
Voltage
121. Check if the Manifold Absolute Pressure (MAP)
sensor reading is over the specified reading.
2. Crank the engine while watching the MAP sen-
sor reading.
Does the MAP sensor read above the specified val-
ue and then change while cranking the engine?4 vGo to Step 13Go to Step 14
13Crank the engine.
Does the Crankshaft Position (CKP) Active Counter
increment while cranking?–Go to Step 16Go to Step 18
14Check the scan data for serial data.
Was serial data lost while cranking the engine?–Go to Step 15Go to ”MAP
Sensor Output
Check”
15Repair voltage loss to the engine control module
(ECM) from the ignition switch.
Is the repair complete?–System OK–
16Check for the presence of spark from all of the igni-
tion wires while cranking the engine.
Is spark present from all of the ignition wires?–Go to Step 41Go to Step 17
171. Measure the resistance of the ignition wires.
2. Replace any of the ignition wire(s) with a resist-
ance above the value specified.
3. Check for the presence of spark from all of the
ignition wires.
Is spark present from all of the ignition wires?30,000 WGo to Step 3Go to Step 18
181. Turn the ignition OFF.
2. Disconnect the Crankshaft Position (CKP) sen-
sor connector.
3. Measure the voltage between the CKP connec-
tor terminals 1 and 3.
4. Repair the wiring as needed.
Does the voltage measure near the value specified?1.4 v (2.5 v)*Go to Step 19Go to Step 20
19Measure the voltage between the CKP connector
terminals 2 and 3.
Does the voltage measure near the value specified1.4 v (2.5 v)*Go to Step 26Go to Step 21
20Measure the voltage between the CKP connector
terminals 1 and ground.
Does the voltage measure near the value specified?1.4 v (2.5 v)*Go to Step 22Go to Step 23
21Measure the voltage between the CKP connector
terminals 2 and ground.
Does the voltage measure near the value specified?1.4 v (2.5 v)*Go to Step 22Go to Step 24
22Check for an open or short in the wire between the
CKP connector terminal 3 and ground.
Is the problem found?–Go to Step 25Go to Step 40
23Check for an open or short in the wire between the
CKP connector terminal 1 and the ECM connector
terminal M21
Is the problem found?–Go to Step 25Go to Step 40

1F – 120IENGINE CONTROLS
DAEWOO V–121 BL4
J3B11F51
BRNORN
/BLK
DIAGNOSTIC TROUBLE CODE (DTC) P0112
INTAKE AIR TEMPERATURE SENSOR LOW VOLTAGE
Circuit Description
The Intake Air Temperature (IAT) Sensor uses a thermis-
tor to control the signal voltage to the engine control mod-
ule (ECM). The ECM supplies a 5 volt reference voltage
and a ground to the sensor. When the air is cold, the resist-
ance is high ; therefore IAT sensor signal voltage will be
high. If the intake air is warm, resistance is low ; therefore
the IAT sensor signal voltage will be low.
Conditions for Setting the DTC
S IAT voltage is less than 0.01V.
Action Taken When the DTC Sets
S The Malfunction Indicator Lamp (MIL) will illuminate
after three consecutive trip with a fail.
S The ECM will record operating conditions at the
time the diagnostic fail. This information will be
stored in the Freeze Frame and Failure Records
buffers.
S A history DTC is stored.S The ECM will default to 605C(1405F) for intake air
temperature. The scan tool will not show the de-
faulted value.
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 10 sec-
onds.
Diagnostic Aids
If the vehicle is at ambient temperature, compare the IAT
sensor to the engine coolant temperature(ECT) sensor.
The IAT sensor and the ECT sensor should be relatively
close to each other. Use the temperature vs. Resistance
Values table to evaluate the possibility of a skewed sensor.
Refer to ”Temperature vs. Resistance” in this section.

1F – 122IENGINE CONTROLS
DAEWOO V–121 BL4
J3B11F51
BRNORN
/BLK
DIAGNOSTIC TROUBLE CODE (DTC) P0113
INTAKE AIR TEMPERATURE SENSOR HIGH VOLTAGE
Circuit Description
The Intake Air Temperature (IAT) Sensor uses a thermis-
tor to control the signal voltage to the engine control mod-
ule (ECM). The ECM supplies a 5 volt reference voltage
and a ground to the sensor . when the air is cold, the resist-
ance is high ; therefore IAT sensor signal voltage will be
high. If the intake air is warm, resistance is low ; therefore
the IAT sensor signal voltage will be low.
Conditions for Setting the DTC
S IAT voltage is less than 4.99V.
Action Taken When the DTC Sets
S The Malfunction Indicator Lamp (MIL) will illuminate
after three consecutive trip with a fail.
S The ECM will record operating conditions at the
time the diagnostic fail. This information will be
stored in the Freeze Frame and Failure Records
buffers.
S A history DTC is stored.S The ECM will default to 605C(1405F) for intake air
temperature. The scan tool will not show the de-
faulted value.
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 10 sec-
onds.
Diagnostic Aids
S If the vehicle is at ambient temperature, compare
the IAT sensor to the engine coolant temperature
(ECT) sensor. The IAT sensor and the ECT sensor
should be relatively close to each other.
S Use the temperature vs. Resistance Values table to
evaluate the possibility of a skewed sensor. Refer
to ”Temperature vs. Resistance” in this section.

ENGINE CONTROLS 1F – 125
DAEWOO V–121 BL4
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 con-
trol 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:
S Fuel delivery.
S Lock Up Clutch (LUC).
S Ignition.
S Evaporative Emission (EVAP) Canister Purge
Valve.
S Electric cooling fan.
Conditions for Setting the DTC
S ECT voltage is less than 0.03V.
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
buffers.
S A history DTC is stored.
S The coolant fan turns ON.
S 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).
S The scan tool will not show the defaulted value.
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
After the engine has started, the ECT should rise steadily
to about 90°C (194°F) then stabilize when the thermostat
opens.
Use the temperature vs. Resistance values table to evalu-
ate the possibility of a skewed sensor. Refer to ”Tempera-
ture vs. Resistance” in this section.

1F – 128IENGINE CONTROLS
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P0118
ENGINE COOLANT TEMPERATURE SENSOR HIGH
VOLTAGE
Circuit Description
The coolant temperature sensor (ECT) uses a thermistor
to control the signal voltage to the engine control module
(ECM).
he ECM supplies a voltage on the signal circuit to the sen-
sor. 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:
S Fuel delivery.
S Lock Up Clutch (LUC).
S Ignition.
S Evaporative Emission (EVAP) Canister Purge
Valve.
S Electric cooling fan.
Conditions for Setting the DTC
S ECT voltage is greater than 4.98V.
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
buffers.
S A history DTC is stored.
S The coolant fan turns ON.
S 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
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
After the engine has started, the ECT should rise steadily
to about 90°C (194°F) then stabilize when the thermostat
opens.
Use the temperature vs. Resistance values table to evalu-
ate the possibility of a skewed sensor. Refer to ”Tempera-
ture vs. Resistance” in this section.