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FUEL SYSTEM (PGM-FI)
PGM-FI TROUBLESHOOTING INFORMATION
GENERAL TROUBLESHOOTING
Interm ittent
Failure
The term
"i
ntermittent 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
wi
th
the trouble. If the MIL was
on,
but then
went
out,
the
or
iginal problem may be
intermittent.
Opens
and
Shorts
"Opens·
and
"Shorts·
are
com
mon
electrical
terms.
An open is a
break
in
a
wire or at a
con
nection. 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 al
all.
With
PCMs
this can mean something will
work,
but not the way it's supposed to.
If
the Mil
has
come
on
Refer to
DTe
READ OUT
(page
6-12).
If
the
MIL
did
not
stay
on
If the MIL did not stay
on,
but there is a
dr
iveability
problem, do the SYMPTOM TROUBLESHOOTING (page
6-6).
SYSTEM DESCRIPTION
SELF·
DIAGNOSIS
SYSTEM
The PGM-FI
system is equipped with
the
self-diagnostic
system.
When any abnormality occurs in the system, the PCM
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 abno
rmality
is
detected
in
the fuel
injector
and
crankshaft
posi-
tion (CKP)
sensor, the fail -safe function
stops
the engine to
protect
it
from damage.
DTC (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 PCM
with the
HOS
pocket tes ter.
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
MAP,
ECT, TP
and
IAT
sensor
diagnosis
will
be made
according to
the
voltage output of
the affected
sensor.
If
a
failure occurs, the PCM
deter
mines the
Function
Failure,
compa res
the
sensor voltage output
to the
standard value,
and
then
ou
tputs the
corresponding
OTC
t
o the HOS Pocket Tester.
For example:
- If the output
voltage
line
(A) on
the MAP
sensor is opened, the
PCM/ECM detects the
output voltage is about 5 V, then
the OTC 1-2
(MAP sensor circuit
high
voltage) will be
displayed.
-
If the input voltage line
(B)
on
the
TP
sensor is opened, the
PCM/ECM detects the
output voltage is 0 V, then the
OTC
8-1 (TP
sensor circuit low voltage)
will be
displayed.
5V
MAP
SENSOR
5V
TPSENSOR
5V
r-~?-- (BI--<?--'
>-=--9-
(AI-
-9--+-
OUTPUT VOLTAGE
- <?-- -+---t-
OUTPUT
VOLTAGE
5V
->-
_~
V
EeT
SENSOR
IATSENSOR
*
OU
TPUT
VOLTAGE
*
OU
TPUT VOLTAGE
.,1
.,1
6-11
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Troubleshooting
