ENGINE CONTROLS 1F–13
DAEWOO M-150 BL2
Data Link Connector (DLC)
The provision for communicating with the control mod-
ule is the Data Link Connector (DLC). The DLC is used
to connect to a scan tool. Some common uses of the
scan tool are listed below:
D Identifying stored DTCs.
D Clearing DTCs.
D Performing output control tests.
D Reading serial data.
DTC TYPES
Each Diagnostic Trouble Code (DTC) is directly related
to a diagnostic test. The Diagnostic Management Sys-
tem sets DTCs based on the failure of the tests during a
trip or trips. Certain tests must fail two consecutive trips
before the DTC is set. The following are the three types
of DTCs and the characteristics of those codes:
Type A
D Emissions related.
D Requests illumination of the Malfunction Indicator.
Lamp (MIL) of the first trip with a fail.
D Stores a History DTC on the first trip with a fail.
D Stores a Freeze Frame (if empty).
D Stores a Fail Record.
D Updates the Fail Record each time the diagnostic test
fails.
Type B
D Emissions related.
D “Armed” after one trip with a fail.
D “Disarmed” after one trip with a pass.
D Requests illumination of the MIL on the second con-
secutive trip with a fail.
D Stores a History DTC on the second consecutive trip
with a fail (The DTC will be armed after the first fail).
D Stores a Freeze Frame on the second consecutive
trip with a fail (if empty).
Type Cnl
D Non-Emissions related.
D Does not request illumination of any lamp.
D Stores a History DTC on the first trip with a fail .
D Does not store a Freeze Frame.
D Stores Fail Record when test fails.
D Updates the Fail Record each time the diagnostic test
fails.
Type E
D Emissions related.
D “Armed” after two consecutive trip with a fail.
D “Disarmed” after one trip with a pass.
D Requests illumination of the MIL on the third consec-
utive trip with a fail.
D Stores a History DTC on the third consecutive trip
with a fail (The DTC will be armed after the second
fail).
D Stores a Freeze Frame on the third consecutive trip
with a fail (if empty).
Important: For 0.8 SOHC engine eight fail records can
be stored. Each Fail Record is for a different DTC. It is
possible that there will not be Fail Records for every
DTC if multiple DTCs are set.
Special Cases of Type B Diagnostic Tests
Unique to the misfire diagnostic, the Diagnostic Execu-
tive has the capability of alerting the vehicle operator to
potentially damaging levels of misfire. If a misfire condi-
tion exists that could potentially damage the catalytic
converter as a result of high misfire levels, the Diagnos-
tic Executive will command the MIL to “flash” as a rate of
once per seconds during those the time that the catalyst
damaging misfire condition is present.
Fuel trim and misfire are special cases of Type B diag-
nostics. Each time a fuel trim or misfire malfunction is
detected, engine load, engine speed, and Engine Cool-
ant Temperature (ECT) are recorded.
When the ignition is turned OFF, the last reported set of
conditions remain stored. During subsequent ignition
cycles, the stored conditions are used as a reference for
similar conditions. If a malfunction occurs during two
consecutive trips, the Diagnostic Executive treats the
failure as a normal Type B diagnostic, and does not use
the stored conditions. However, if a malfunction occurs
on two non-consecutive trips, the stored conditions are
compared with the current conditions. The MIL will then
illuminate under the following conditions:
D When the engine load conditions are within 10% of
the previous test that failed.
D Engine speed is within 375 rpm, of the previous test
that failed.
D ECT is in the same range as the previous test that
failed.
READING DIAGNOSTIC TROUBLE
CODES
The procedure for reading Diagnostic Trouble Code(s)
(DTC) is to use a diagnostic scan tool. When reading
DTC(s), follow instructions supplied by tool manufactur-
er.
Clearing Diagnostic Trouble Codes
Important: Do not clear DTCs unless directed to do so
by the service information provided for each diagnostic
procedure. When DTCs are cleared, the Freeze Frame
and Failure Record data which may help diagnose an in-
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