Daewoo CIELO EURO III Manual page 418

1F – 248 ENGINE CONTROLS
System Description
The Knock Sensor (KS) system is used to detect engine
detonation, allowing the
engine control module (ECM) to retard ignition
control spark timing based on the KS signal being re-
ceived. The KS produces an AC signal so that under a
no knock condition the signal on the KS circuit measures
about 0.007 v AC. The KS signal's amplitude and fre-
quency depend upon the amount of knock being experi-
enced. The ECM contains a non–replaceable
knock filter module called a Signal-to-Noise Enhance-
ment Filter (SNEF) module. This filter module in the
ECM determines whether knock is occurring by
comparing the signal level on the KS circuit with the volt-
age level on the noise channel. The noise channel al-
lows the ECM to reject any false knock signal by
knowing the amount of normal engine mechanical noise
present. Normal engine noise varies depending on en-
gine speed and load. When the ECM determines
that an abnormally low noise channel voltage level is be-
ing experienced, a DTC P0325 will set.
Conditions for Setting the DTC
1.5L SOHC
Minimum difference between cylinders is greater than
0.4%.
Vacuum is less than 10 to 50 kPa, based on rpm.
RPM is greater than 1600.
Engine Coolant Temperature (ECT) is greater than
50 C(122 F).
Action Taken When the DTC Sets
The MIL will illuminate after three consecutive trip
with a fail (1.5L SOHC).
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.
DIAGNOSTIC TROUBLE CODE (DTC) P0325
KNOCK SENSOR INTERNAL MALFUNCTION
Conditions for Clearing the MIL/DTC
The MIL will turn off after four consecutive ignition
cycles in which the diagnostic runs without a fault
within the freeze frame conditions that the DTC failed
(1.5L SOHC).
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
Check and correct any abnormal engine noise before
using the diagnostic table.
Any circuitry that is suspected as causing the complaint
should be thoroughly checked for the following condi-
tions:
Backed-out terminals
Improper mating
Broken locks
Improperly formed
Damaged terminals
Poor terminal-to-wire connection
Physical damage to the wiring harness
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.
2. If the conditions for the test as described above are
met, a DTC P0325 will set.
4. If the engine has an internal knock or audible noise
that causes a knocking type noise on the engine
block, the KS may be responding to the noise.
6. The replacement ECM must be repro-
grammed. Refer to the latest Techline procedure for
ECM reprogramming.
DAEWOO T-154 BL2,3