Daewoo NUBIRA, User Manual

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1F – 44 I ENGINE CONTROLS
DAEWOO V–121 BL4
NO MALFUNCTION INDICATOR LAMP
Circuit Description
When the ignition is turned ON, the Malfunction Indicator
Lamp (MIL) will momentarily flash on and off, then it will re-
main on until the engine is running if no Diagnostic Trouble
Codes (DTC) are stored. Battery voltage is supplied
through the ignition switch directly to the MIL telltale. The
powertrain control module (PCM)/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 #5 fuse will cause the entire cluster to be
inoperative, and may set DTC P1625.
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 diag-
nostic table.
1. The On–Board Diagnostic (OBD II) System Check
prompts the technician to complete some basic
checks and store the freeze frame and failure re-
cords data on then 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 inopera-
tive, then the fault can be isolated to either the
PCM/ECM ignition feed, The battery feed, or a poor
ground at the engine block, or the PCM/ECM.
6. Probing the MIL circuit with a test light to ground
stimulates the PCM/ECM’s control of the MIL. If the
MIL illuminates, then the malfunction can be iso-
lated to the control of the MIL or a poor connection
at the MIL terminal to the PCM/ECM. Connections
that are suspected of being faulty should be thor-
oughly checked as described in the diagnostic aids.
8. It takes very little resistance for the battery and igni-
tion feed circuits to cause an intermittent condition
and should also be checked for a poor connection
as described in diagnostic aids.