Daewoo CIELO EURO III Manual page 296

1F – 127 ENGINE CONTROLS
ENGINE COOLANT TEMPERATURE (ECT) SENSOR HIGH VOLTAGE
Circuit Description
The Engine Coolant Temperature (ECT) Sensor 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 air 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 control the following items:
Fuel delivery.
Ignition.
Evaporative Emission (EVAP) canister purge valve.
Idle Air Control (IAC) valve.
Electric cooling fan.
Conditions for Setting the DTC
The engine run time is greater than 90 seconds.
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 buff-
ers.
A history DTC is stored.
Both cooling fan turns ON.
DIAGNOSTIC TROUBLE CODE (DTC) P0118
The ECM will substitute a default value for ECT.
The scan tool may not show the defaulted value.
Conditions for Clearing the MIL/DTC
The MIL will turn off after three (four –
1.5L SOHC) 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
Normal operating temperature for the engine cooling
system is between 90 C (194 F) and 95 C (203 F).
Use the Temperature vs. Resistance Values table to
evaluate the possibility of a skewed sensor. Refer to
"Temperature vs. Resistance" in this section.
Test Description
Number(s) below refer to the step number(s) on the
Diagnostic Table.
1. The On-Board Diagnostic (EOBD) System Check
prompts the technician to complete some basic
checks and store the freeze frame and failure re-
cords data on the scan tool if applicable. This
creates an electronic copy of the data taken when
the malfunction occurred. The information is then
stored on the scan tool for later reference.
4. This step simulates a DTC P0117 condition. If the
ECM senses the change, then the ECM
and the ECT wiring are OK.
11. The replacement ECM must be repro-
grammed. Refer to the latest Techline procedure for
ECM reprogramming.
TAA1F160
DAEWOO T-154 BL2,3