Daewoo CIELO EURO III, Manual

Page: 215 / 603

ENGINE CONTROLS 1F – 4 7
DAEWOO T-154 BL2,3
NO MALFUNCTION INDICATOR LAMP
Circuit Description
When the ignition is turned ON, the Malfunction Indica-
tor Lamp (MIL) will be turned ON and remain ON until
the engine is running, if no Diagnostic Trouble Codes
(DTCs) are stored. Battery voltage is supplied through
the ignition switch directly to the MIL telltale. The
engine control module
(ECM) controls the MIL
by providing a ground path through the MIL control
circuit to turn on the MIL.
Diagnostic Aids
An open ignition F11 fuse will cause the entire cluster to
be inoperative.
Check the battery and ignition feed circuits for poor con-
nections if the MIL is intermittent.
Any circuitry that is suspected as causing an intermittent
complaint should be thoroughly checked for backed-out
terminals, improper mating, broken locks, improperly
formed or damaged terminals, poor terminals to wiring
connections, or 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 to 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 stored
in the scan tool for later reference.
3. Connections that are suspected of being faulty
should be thoroughly checked as described in the
diagnostic aids.
4. If the engine fails to start and the MIL is inoperative,
then the fault can be isolated to either the ECM
ignition feed, the battery feed, or a poor ground at
the engine block or at the ECM.
8. It takes very little resistance for the battery and the
ignition feed circuits to cause an intermittent condi-
tion and should also be checked for a poor connec-
tion as described in diagnostic aids.
9. Probing the MIL circuit with a test light to ground
stimulates the ECM’s control of the MIL. If the
MIL illuminates, then the malfunction can be isolated
to the control of the MIL or a poor connection at the
MIL terminal to the ECM. Connections that are
suspected of being faulty should be thoroughly
checked as described in the diagnostic aids.
12. Before replacing the ECM, check for backed
out terminals, improper mating, broken locks, im-
properly formed or damaged terminals, and poor
terminal to wiring harness. Replacement
E CMs
must be reprogrammed. Refer to the latest Techline
information for reprogramming procedures.
21. ECM grounds will only cause a problem if all of
the grounds are not making a good connection. If a
ECM ground problem is suspected, the most
probable place to check is at the engine block,
where all the grounds meet.
22. If not faults have been found at this point and no
DTCs were set, refer to the diagnostic aids for addi-
tional checks and information.