TROUBLESHOOTING
Intermittent Failure
The term "intermittent failure" means a system may have
had
a failure, but it checks OK now. If the MIL does not come
on,
check
for poor contact or loose pins at
all
connectors related to the circuit that of the troubleshooting. If the MIL was on, but then went out,
the original problem may
be
intermittent.
Opens and Shorts
· · "Opens" and "Shorts" are common electrical terms. An open
is
a break
in
a wire or at a connection. A short
is
an
accidental
connection
of
a wire to ground or
to
another wire.
In
simple electronics, this usually means something will not work at all. With
ECMs this can mean something may work, but not the way it's supposed
to.
If the
Mil
has come
on
Refer to OTC READOUT (page
4-11
).
If
the
Mil
did
not
stay
on
If the MIL did not stay
on,
but there
is
a driveability problem, do the SYMPTOM TROUBLESHOOTING (page 4-8).
SYSTEM DESCRIPTION
SELF-DIAGNOSIS SYSTEM
The PGM-FI system
is
equipped with the self-diagnostic system. When any abnormality occurs
in
the system, the
ECM
turns
on
the
MIL and stores a
OTC
in
its erasable memory.
FAIL-SAFE FUNCTION
The PGM-FI system
is
provided with a fail-safe function
to
secure a minimum running capability even when there
is
trouble
in
the
system. When any abnormality
is
detected by the self-diagnosis function, running capability
is
maintained by pre-programed value
in
the simulated program map. When any abnormality
is
detected
in
the fuel injector, the fail-safe function stops the engine
to
protect it from damage.
OTC
(Diagnostic Trouble Code)
• The OTC
is
composed
of
a main code and a sub code
and
it
is
displayed
as
a hyphenated number when retrieved from the
ECM
with the MCS.
The digits
in
front
of
the hyphen are the main code, they indicate the component of function failure.
The digits behind the hyphen are the sub code, they detail the specific symptom of the component or function failure.
For example,
in
the case of the TP sensor:
- OTC 08 - 1 = (TP sensor voltage) - (lower than the specified value)
- OTC 08 - 2 = (TP sensor voltage) - (higher than the specified value).
• The ECT and TP sensor diagnosis will be made according
to
the voltage output of the affected sensor.
If a failure occurs, the ECM determines the Function Failure, compares the sensor voltage output
to
the standard value,
and
then outputs the corresponding
OTC
to
the MCS.
Mil
Blink Pattern
• If the MCS
is
not available,
OTC
can be read from the
ECM
memory by the MIL blink pattern.
• The number
of
MIL blinks
is
the equivalent
to
the main code of the
OTC
(the sub code cannot be displayed by the MIL).
• The MIL will blink the current
OTC,
in
case the ECM detects the problem at present, when the ignition switch
is
ON.
The MIL will
stay ON when the engine speed
is
over 2000 rpm.
The MIL has two types of blinks, a long blink and short blink. The long blinking lasts for 1.3 seconds, the short blinking lasts for
0.3 seconds. One long blink
is
the equivalent
of
ten short blinks. For example, when two long blinks are followed by five short
blinks, the MIL
is
25 (two long blinks= 20 blinks, plus five short blinks).
• When the ECM stores more than one OTC, the MIL will indicate them by blinking
in
the order from the lowest number
to
highest
number.
Mil
Check
When the ignition switch
is
turned ON, the MIL will stay
on
for a few seconds, then go off. If the MIL does not come
on,
troubleshoot
the MIL circuit (page 4-48).
CURRENT OTC/FREEZE
OTC
The OTC
is
indicated
in
two ways according to the failure status.
•
In
case the ECM detects the problem at present, the MIL will come
on
and
the MIL will start to blink
as
its OTC. It
is
possible to
readout the MIL blink pattern
as
the current
OTC.
•
In
case the ECM does not detect any problem at present but has a problem stored
in
its memory, the MIL will not light
and
blink.
If it
is
necessary to retrieve the past problem, readout the freeze
OTC
by following the
OTC
readout procedure (page
4-11
).
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