FUEL SYSTEM
Check engine/malfunctionindicator lamp6w.0093
TROUBLESHOOTINGM13EBADa
EXPLANATION O
F
PROCEDURES
Refer to P.13-8.
TROUBLESHOOTING
EXPLANATION AND PRECAUTION RELATED
TO HARNESS CHECKING
Refer to
P.13-9.
ft&;K ENGINE/MALFUNCTION INDICATO
R
Among the on-board diagnostic items, a check engine/mal-
function indicator lamp comes on to notify the driver of the
emission control items when an irregurality is detected. However, when an irregular signal returns to normal and the
engine control module judges that it has returned to normal,
the check engine/malfunction indicator lamp goes out. Moreover, when the ignition switch is turned off, the light goes
out. Even if the ignition switch is turned on again, the light does
not come on until the irregularity is detected. Here, immediately after the ignition switch is turned on, the
check engine/malfunction indicator lamp is lit for 5 seconds to
indicate that the check engine/malfunction indicator lamp op-
erates normally.
ITEMS INDICATED BY THE CHECK ENGINE/
MALFUNCTION INDICATOR LAMP
Engine control module
Heated oxygen sensor
Volume air flow sensor
Intake air temperature sensor
Throttle position sensor
Engine coolant temperature sensor
Crankshaft position sensor
Camshaft position sensor
Barometric pressure sensor
Knock sensor
Injector
Fuel pump
EGR
Ignition coil, Ignition power transistor unit
CHECK ENGINE/MALFUNCTION INDICATOR LAMP INSPECTION
(1) Check to be sure, when the ignition switch is set to the “ON” position, that the lamp illuminates for about five sec-
onds and then switches OFF.
(2) If the lamp does not illuminate, check for damage or dis-
connection of the harness, or for a blown fuse or a failed
light bulb.
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13-206FUEL SYSTEM
ON-BOARD DIAGNOSTIC
The engine control module monitors the input/out- put signals (some signals at all times and the others
under specified conditions) of the engine control
module.
When it is noticed that an irregularity has continued
for a specified time or longer from when the irregu- lar signal is initially monitored, passing a certain
number, the engine control module judges that an
irregularity has occurred, memorizes the diagnostic
trouble code, and outputs the signal to the on-board diagnostic output terminal.
There are 16 on-board diagnostic items, including
the normal state, and the diagnostic results can be read out with a voltmeter or scan tool.
Moreover, since memorization of the diagnostic
trouble codes is backed up directly by the battery,
the diagnostic results are memorized even if the ig- nition key is turned off. The diagnostic trouble
codes will, however, be erased when the battery
terminal or the engine control module connector is
DIAGNOSTIC CHART (FAULT TREE) disconnected. In addition, beginning with the engine
control module of 1990 and later models, the diag- nostic trouble code are erased by turning on the ig-
nition switch and sending the diagnostic trouble
code erase signal from the scan tool to the engine
control module.
Caution If the sensor connector is disconnected with
the ignition switch turned on, the diagnostic
trouble code is memorized. In this case, send
the diagnostic trouble code erase signal from
the scan tool to the engine control module or disconnect the battery terminal
(-) for 10 sec-
onds or more, and the diagnosis memory will be erased.
The 16 on-board diagnostic items are provided as
follows, and if plural items are activated, they are all indicated sequentially from the smallest code num-
ber. ti0.
Diagnostic trouble code
Output signal pattern
On-boarddiagnostic
itemCheck item (Remedy)
-Engine (Replace engine control module)
control
H Imodule
L-
J
12A0104
Heatedoxygen
sensor
l Harness and connectorl Heated oxygen sensorl Fuel pressurel Injectors (Replace if defective.) 12A0104l Intake air leaks
12
13 12A0104Volume airl Harness and connector
flow sensor(If harness and connector are
normal, replace volume air flow
sensor assembly.)
Intake air
l Harness and connector
temperaturel intake air temperature sensorsensor 12A0104
Memory
Retained
Retained
Retained
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FUEL SYSTEM
No.
14
Diagnostic trouble code On-board
Output signal pattern diagnostic
item Check item (Remedy)
Memory
Throttle l Harness and connector Retained
:-
position
l Throttle position sensor
sensor l Closed throttle position switch
12A0104
21Engine
l Harness and connector Retained
:nn
coolant
l Engine coolant temperature
temperature sensor
sensor 12A0107
22Crankshaft
l Harness and connector Retained
:nn
position
(If harness and connector are
sensor normal, replace crankshaft
position assembly.) 12A0107
23Camshaft
position
sensor l Harness and connector
(If harness and connector are
normal, replace crankshaft
position assembly.) Retained 12A0107
I
24
25Vehicle l Harness and connector Retained
Hspeed
sensor (reedl Vehicle speed sensor (reed
Lswitch)
switch)
12A0107-.
Barometric
l Harness and connector Retained
H
ULJuuuvl
pressure
(If harness and connector are
sensor normal, replace barometric
Lpressure sensor assembly.) 12A0107
31Knockl Harness and connector
Retained
:-
sensor
12RO468from 1992
models>
Injector l .Harness and connector
l Injector coil resistance Retained
12AO105I
12Fuel pump
l Harness and connector Retained
Hl Multiport fuel injection relay
Luuul I-Ill
12AO105I
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13-208FUEL SYSTEM
No.
43
Diagnostic trouble codeOn-board
diagnostic Check item (Remedy) Memory
Output signal pattern item
EGRl Harness and connector Retained
H
nia>l EGR valve
l EGR solenoid
L 12A0105
l EGR valve control vacuum
44 Ignition coil,
l Harness and connector Retained
Hl Ignition coil
LUUULnl-lM-
Ignition
power l Ignition power transistor
transistor 12A0105
unit
-Normal --
stateH
Lnm 12A0104
NOTEReplace the engine control module if a diagnostic trouble code is output\
although the inspection reveals that there is no
problem with the check items.
TROUBLESHOOTING TABLE
NOTE
* : The failsafe/back-up function is in operation.
Diagnostic On-boardtroublediagnosticcode No.itemDiagnostic content
Major causeRemarks (trouble
phenomenon, etc.)
-EngineThe engine control module-l Engine stop
control itself is abnormal. l Impossible start
module
11Heated Though the air/fuel mixture (1) The heated oxygen sensor is l Deterioration of
oxygen ratio closed loop control is
troubled.exhaust gas
sensor operated, the signal voltage of
(2) Open-circuit, short-circuit or purifying
the heated oxygen sensor improper connector contactperformance*
does not vary (to be lean/rich). occurs in the heated oxygen
sensor circuit.
(3) The fuel pressure is improper. l Deterioration of
(4) The injector is troubled. exhaust gas
(5) Air is sucked through the purifying
gasket clearance, etc. performance*
(6) The engine control module is l Abnormal start
troubled. l Unstable idling
l Abnormal acceleration
12;zc$rne air Though the engine is running,
(1) Volume air flow sensor is l Abnormal
the signal
frequency of the
troubled. acceleration*
sensor volume air flow sensor is
(2) Open-circuit, short-circuit or l Improper idling
1 OHz or less.
improper connector contact revolution speed*
occurs in the volume air flow l Unstable idling*
sensor circuit.
(3) The engine control module is troubled.
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FUEL SYSTEM
agnostic On-boardtroublediagnosticode No.item
Diagnostic content
Major causeRemarks (trouble
phenomenon, etc.)
13Intake air (1) The signal voltage of the
(1) The intake air temperature l Slightly impropertemperatu-intake air temperature
sensor is troubled.driveability*re sensorsensor is 4.5V or higher.(2) Open-circuit, short-circuit or l At high
(2) The signal voltage of the improper connector contacttemperatures,
intake air temperature occurs in the air intake
(a) Improper start*
sensor is
0.27V or lower. temperature sensor circuit. (b)Unstable
idling’
(3) The engine control module is
troubled.
14Throttle
position
sensor (1) The signal voltage of the
(1) The throttle position sensor is l Slightly improper
throttle position sensor is troubled or improperly acceleration
0.2V or lower.adjusted.
(2) Though the closed throttle (2) Open-circuit, short-circuit or l Improper
position switch is on, the improper connector contact driveability
signal voltage of the occurs in the throttle position
throttle position sensor is
sensor circuit. l Engine stop2V or higher.
(3) The closed throttle position l Engine stop
switch ON is troubled.
(4) The closed throttle position l Racing is
switch signal line is impossible
short-circuited.
(5) The engine control module is
troubled.
21Engine(1) The signal voltage of the (1) The engine coolant During cold weather,
coolant engine coolant temperature sensor is troubled.
l Starting is
temperatu-temperature sensor is(2) Open-circuit, short-circuit or
impossible.*re sensor4.6V or higher.improper connector contact l Unstable idling*
(2) The signal voltage of the occurs in the engine coolant0 Improper
engine coolant temperature sensor circuit.
acceleration*
temperature sensor is (3) The engine control module is
0.1 1 V or lower.troubled.
‘(3) During engine warming-up, the engine
coolant temperature
sensor signal indicates
that the engine coolant
temperature drops.
22Crankshaft Though the engine is cranking (1) The crankshaft position sensor
l Engine s,tOp
position4 seconds or more, the signal is troubled.0 Starting Is
sensor
voltage of the crankshaft (2) Open-circuit, short-circuit or
impossible.
position sensor does not vary improper connector contact
(to be high/low). occurs in the crankshaft
position sensor circuit.
(3) The engine control module is
troubled.
23Camshaft Though the engine is running,
(1) The camshaft pOSitiOn
Sensor iSl Engine stoP*position the signal voltage of the troubled.
sensor camshaft position sensor does
(2) Open-circuit, short-circuit or
not vary (to be high/low). improper connector contact
occurs in the camshaft position
sensor circuit.
(3) The engine control module is
troubled.
24Vehiclespeed
sensor
(reed
switch) During acceleration of engine
(1) The vehicle speed sensor is The engine
revolution speed of 3,000 rpm troubled.sometimes cuts off
or more, the signal voltage of (2) Open-circuit, short-circuit or when stopping after
the vehicle speed sensor does improper connector contact
deceleration.
not vary (to be high/low). occurs in the vehicle speed
sensor circuit.
(3) The engine control module is
troubled.
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c
13-210FUEL SYSTEM
Xaia;;;ic On-boarddiagnostic
code No.item Diagnostic content
Major causeRemarks
(troublephenomenon, etc
25Barometric
(1) The signal voltage of the (1) The barometric pressure sensor l Unstable idling*
pressure barometric pressure is troubled. l Improper
sensor sensor is
4.5V or higher.(2) Open-circuit, short-circuit or
acceleration*
(2) The signal voltage of the improper connector contact0 Improper start*
barometric pressure occurs in the barometric
sensor is
0.2V or lower. pressure sensor circuit.
(3) The engine control module is
troubled.
31Knocksensor Open-circuit in the knock
sensor circuit. (1) The knock sensor is troubled.
(2) Open-circuit, short-circuit or
improper connector contact
occurs in the knock sensor
circuit.
0 Improper acceleration*
(3) The engine control module is troubled.
41Injector Injector is not continuously
driven for 4 seconds during
engine cranking or idle
operation. (1) The injector is troubled.
(2) Open-circuit, short-circuit or
improper connector contact
occurs in the injector sensor
circuit.
(3) The engine control module is
troubled. l Unstable idling0 Improper
acceleration
0 Improper start
42Fuel pump The engine runs but power to (1) Open-circuit, short-circuit or
l Impossible start
drive the motor is not supplied improper connector contactl Engine stop
to the fuel pump. occurs in the fuel pump power
supply circuit.
(2) The
multiport fuel injection
relay is troubled.
(3) The engine control module is
troubled.
43
EGRDuring engine running after (1) The EGR valve is not opened. l Deterioration of
EGR valve control is excessively purifying
(The signal voltage of the low. performance
EGR temperature sensor (3) The EGR solenoid
is troubled.
is excessively high.) (4) The EGR temperature sensor is
(2) The signal voltage of the troubled.
EGR temperature sensor (5) Open-circuit, short-circuit or
is 0.1 V or less.improper connector contact
occurs in the EGR temperature
sensor circuit.
(6) The engine control module
troubled.
44 Ignition
During engine running, the
(1) The ignition coil is troubled. l Unstable idling*
coil/ignitio-ignition signal is not input.
(2) Open-circuit, short-circuit or0 Impropern powerHowever, cases in which
improper connector contact acceleration*
transistor ignition signals are input to all
occurs in the igntion primaryl Improper start*
unit cylinders are excluded.
circuit.
(3) The ignition power transistor
unit is troubled.
(4) The engine control module is
troubled.
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1
FUEL SYSTEM
FAILSAFE/BACK-UP FUNCTIONS LIST
If trouble with any major sensor is detected by the on-board diagnostic,\
the vehicle will be kept in the safe
driving conditions-accdrding
to the preset control
logic.
Trouble item
Volume air flow
sensor Control content for trouble
(1) Fuel injection timing and ignition timing are determined according\
to the throttle positior
sensor (TPS) and engine revolution speed signal (crankshaft position \
sensor signal).
(2) The idle air control motor is fixed at the specified position, and\
the idle revolution speec
control is not executed.
Intake air
temperature sensor The control is executed with the suction air temperature regarded as
25’C (77°F).
Throttle positron
sensor (TPS)The fuel injection rate is not increased for acceleration according to t\
he throttle positionsensor signal.
Engine coolant
temperature sensor The control IS executed with the engine coolant temperature regarded as 80°C
(176°F).(Even if the sensor signal becomes normal again, the control is continu\
ed until the ignition
switch is turned off.)
Camshaft position
sensor (1) Simultaneous injection of fuel is executed for all cylinders.
(In this case, the No.
1 cylinder top dead center is not detected at all after the ignition
key is turned on.)
(2) Fuel is cut 4 seconds after trouble is detected. (In this case, the No. 1 cylinder top dead center IS not detected at all after the ignition
key is turned on.)
Barometric pressure
sensor The control is executed with the pressure regarded as 760
mmHg (30 in.Hg.).
Knocksensor
The ignition timing is retarded further from the normal state, and ignit\
ion is executed even
when knocking does not occur.
Ignition coil, ignition
power transistor unitFuel is cut in the cylinder where the ignition signal is abnormal.
Heated oxygen sensor Closed loop control of the air/fuel mixture ratio is not executed.
TSB RevisionREAD OUT OF DIAGNOSTIC TROUBLE CODE
Refer to
P.13-16.
CLEAR MEMORY OF DIAGNOSTIC TROUBLE
CODE
Refer to P.13-17.
13-212
FUEL SYSTEM
CHECK CHART CLASSIFIED BY PROBLEM SYMPTOMS Starting Idling
stability Driving
>
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zx .-
E
EE 2-80’
52FCheck
Itemsz gp ~ =
gif8e
5;ms00 a,L%a‘;E
2
F5i5 .-
5scp ‘-re,t2aDo’6%.fP .xz YPfbz 2 ‘5 uE22
%il= 5
8
8 8gzzg-c$z8
z
Power
supply
and
ignition switch-IGOnI
255
Engine
control
module power ground
@ [ZI
45
Fuel
pumpoI51oulolIioDloiIl258
Jolume
air
flow sensorcam@Ea@@l@EilO[41@ q 261
‘ntake
air
temperature sensor0OlEiiOEtl@ q 263
3arometric
pressure
sensor0@lB@El@ q 266
Fngine coolant temperature sensorEloiIlomoaol7loEloDO@ 268
Throttle
position
sensor
@[email protected]
Closed throttle
position
switch0[51@D@D0[[email protected]
Tamshaft position
sensorOrnOlsl@Elam277,27
Crankshaft
position
sensor@El@[email protected]
gnltion
switch-ST
anitlon switch-ST and park/neutral)os,t,on switch @ElODl@ 78
/ehlcle
speed
sensor
00
80
‘ower
steering
oil
pressure
switch081
w conditlonlng swtch andr/C compressor clutch relay0285
knock sensor:Turbo. Non-Turbo From 1992 models>@ q 287
ieated oxygen
sensor
@290.29
njectors
@,[Hl@lzl@lz3@,161@Di080151@El
295
die air
control
motor (stepper
motor)0[63@!zl@al0863298 gnition
coil
and ignition
power transistor 0 m@El @El@ a 302.30’ Evaporative emission
purge
solenoid
0
99
iGR
solenoid@LaOK3@II3101
uel
pressure
solenoid
urbocharger waste gate contrololenoid
309
‘uel
pressureOD@l5l@D@D012100
312
0:
Warm
engine (Figures
inside
the 0 indicate the checking sequence.)a: Cold engine (Figures
inside
the q indicate
the checking
sequence.)
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