check engine MITSUBISHI GALANT 1989 Service Workshop Manual

13-8
FUEL SYSTEM - Troubleshooting
TROUBLESHOOTING
EXPLANATION OF TROUBLESHOOTING PROCEDURESMlBEBAD
Effective troubleshooting procedures related to problems of the MFI
system are described below.
START
1. Confrrmatron of the mal-functron.
2. Read-out of the diag-
nostic trouble code.
I
I
3. Assumption of the prob-
able cause of the mal-
function, and deter-
mrnatron of theappropriate checkpoints.
4. Checking of the engine
control module’s inputand output signals.
6. Checking of the
MFIcomponent itself.
8. Confirmation that repair procedures have been
completed and thatreoccurrence has been
prevented.
I. Confirmation of the malfunction.lCause the malfunction to reoccur and check the details
of the malfunction and the conditions (engine condition,
driving conditions, etc.) when the malfunction reoccurs.
2.Read-out of the diagnostic trouble code.
lWhen the diagnostic trouble code is read out and the diagnostic trouble code is output, refer to the diagnos-
tic chart and repair the indicated location of the mal- function.
3.Assumption of the probable cause of the malfunction, and
determination of the appropriate check points.
lRefer to the “CHECK CHART CLASSIFIED BY PROB-
LEM SYMPTOMS” and confirm the sequence of check-
ing for the indicated malfunction.
4. Checking of the engine control module’s input and output signals.
0Using the scan tool or an oscilloscope, check the input
and output signals of the engine control module.
aIf the input and output signals are normal, sensor input/
actuator control can. be judged to be normal, so check
the input and output signals of the subsequent check point.
5.Checking of the MFI
component’s harness.lIf an abnormal condition of the input and output signals
of the engine control module is discovered, check, and
repair if necessary, the body harness of the
MFI com-
ponent.
lAfter making this repair, again check the input and out- put signals of the engine control module; if they are
normal, proceed to the checking of the input and out-
put signals of the subsequent check point.
6.Checking of the MFI
component itself.aIf the input and output signals of the engine control
module are abnormal even though the body harness is
normal, check the MFI component itself, and repair or
replace as necessary.
lAfter making this repair or replacement, again check
the input and output signals of the engine control mod-
ule; if they are normal, proceed to the checking of the
input and output signals of the subsequent check point.
7.Rechecking of the cause of the malfunction, and repair.lIf the input and output signals of the engine control
module are abnormal even though the harness check-
ing and the checking of the unit itself indicate that the
condition is normal, refer to the troubleshooting hints to recheck the probable cause, and then check other
groups and reapir as necessary.
8. Confirmation that repair procedures have been completed and that reoccurrence has been prevented.
lPerform a test to try to get the malfunction to reoccur,
and confirm that it does not.
aEliminate the true cause of the malfunction so as to
prevent its reoccurrence.
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13-10
FUEL SYSTEM - TroubleshootingTerminal
at sensor side
1\~“‘,““W,O,’ ‘\*N 4-cnDQ5a,, \llllf,,
c 3 c-11 ‘.<-!
( .[&
;%* \ g ~ &.$$~&%,;
0%: E
.Oj-,,
giI lOWI -,n
/ ~ ( ~~‘-~~~
-.mo .u. m,.0 - rj*> ;; Check engine/malfunction
indicator lamp68AOO93
l
If the voltage (power-supply voltage) supplied to a sensor
is not normal, repair the harness. If the voltage to the sensor is still not normal after the har-
ness has been repaired, repalce the engine control module
and check again.
W&K ENGINE/MALFUNCTION INDICATOR
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
andthe
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 turn 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
1 Enaine control module
IOxvaen sensorI
IVolume air flow sensorIIntake air temperature sensor
Throttle position sensor
Engine coolant temperature sensor
Idle speed control motor position sensor
Crankshaft position sensor
Camshaft position sensor
Barometric rxessure sensor
Injector
Fuel pump
EGR
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 failedlight bulb.
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FUEL SYSTEM - Troubleshooting13-11
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 15 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 disconnected. In addition, beginning with the engine
control module of
1990 and later models, the diag-
nostic trouble codes are erased by turning on the
ignition 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 diagnostic memory will
be erased.
The 15 on-board diagnostic items are provided as
follows, and if plural items are activated, they are all
indicated sequentially from the smallest code num-
I---
terminal or the engine control module connector is
uer
DIAGNOSTIC CHART (FAULT TREE)
No.
-
Diagnostic trouble code On-board
diagnostic
Check item (Remedy) MemoryOutput signal patternitem
-Engine(Replace engine control module)
control
:r
module 12A0104
11Oxygenl Harness and connector
Retained
sensor0 Oxygen sensor
:-JLJ--
. Fuel pressure
l Injectors (Replace if defective.)
l Intake air leaks 12A0104
12Volume air
l Harness and connector
Retained
flow sensor (if harness and connector are
:-JJ-M-
normal, replace volume air flow
sensor assembly.) 12A0104
13 Intake air
l Harness and connector
Retained
temperature l Intake air temperature sensor
:n
sensor 12A0104
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13-12
FUEL SYSTEM - Troubleshooting
No.
14
Diagnostic trouble code
On-board
diagnostic Check item (Remedy)
Memory
Output signal pattern item
Throttle l Harness and connector
Retained
position l Throttle position sensor
:-
sensor l Closed throttle position switch 12A0104
15
Idle
speed l Harness and connector
Retained
control l Idle speed control motor
n
motor
position sensor
position l Throttle position sensor
sensor 12A0104
21
Enginel Harness and connector Retained
coolant l Engine coolant temperature
“=
temperature
sensor
sensor 12A0107
22Crankshaft
l Harness and connector
Retained
position (If harness and connector are
:-
sensor normal, replace distributor
assembly.) 12A0107
23Camshaft
l Harness and connector
Retained
position (If harness and connector are
:=
sensor normal, replace distributor
assembly.) 12A0107
24Vehicle
l Harness and connector
Retained
speed l Vehicle speed sensor (reed
H
uulnnn
sensor (reed
switch)
switch)
L 12A0107
25Barometric
l Harness and connector
Retained
pressure (If harness and connector are
H
ULnMnn
sensor
normal, replace barometric
pressure sensor assembly.)
L 12A0107
41Injector
l Harness and connector
Retained0 Injector coil resistance
:a 12A0105
42Fuel pump
l Harness and connector
Retained
l Multiport fuel injection relay
Luuul nn
12A0105
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FUEL SYSTEM - Troubleshooting13-13
No.
43
4
-
Diagnostic trouble code
Output signal pattern On-board
diagnostic item Check item (Remedy)
Memory
EGRl Harness and connector
Retainedl EGR valve
l EGR solenoid
L u u u I nnnl EGR valve control vacuum12A0105
Normal -state
-
H
L12A0104I 1
NOTEReplace the engine control module if a diagnostic trouble code is output\
although the inspection reveals that there is no
oroblem
with the check items.
TROUBLESHOOTING TABLE NOTE
*:The failsafe back-up function is in operation.
Diagnostic On-board
trouble diagnostic Diagnostic content
code No.item Major cause
Remarks (trouble
phenomenon, etc.)
-EngineThe engine control module-l Engine stop
control itself is abnormal. l Impossible start
module
11Oxygen Though the air/fuel mixture (1) The oxygen sensor is troubled.
l Deterioration of
sensor ratio closed loop control is (2) Open-circuit, short-circuit or
exhaust gas
operated, the signal voltage of improper connector contactpurifying
the oxygen sensor does not occurs in the oxygen sensorperformance*
vary (to be lean/rich). 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
12Volume
air flow
sensor Though the engine is running,(I) Volume air flow sensor is
l Abnormal
the signal frequency of the air troubled.acceleration*
flow sensor is
1 OHz or less. (2) Open-circuit, short-circuit or
improper connector contact
occurs in the volume air flow
sensor circuit.
(3) The engine control module is l Unstable idling*
troubled.
13Intake air (1) The signal voltage of the (1) The intake air temperature
l Slightly impropertemperatu-intake air temperaturesensor 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 contact
temperatures,
intake air temperature occurs in the air intake
(a) Improper start*
sensor is
0.27V or lower. temperature sensor circuit.
(3) The engine control module is(b) ;J;pe
troubled.
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13-16
FUEL SYSTEM - Troubleshooting
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 according to the preset control logic.
Trouble item Control content for trouble
Volume air flow Fuel injection timing and ignition timing are determined according to th\
e throttle position
sensor sensor
(TPS) and engine revolution speed signal (crankshaft position sensor signal)\
.
Intake air temperature The control is executed with the suction air temperature regarded as
25°C (77°F).
sensor
Throttle position The fuel injection rate is not increased for acceleration according to t\
he throttle position
sensor
(TPS)sensor signal.
Idle speed control After the idle speed control motor plunger is driven and contracted, the\
idle revolution speed
motor position sensor is not controlled.
Engine coolant The control is executed with the engine coolant temperature regarded as \
8OO.C (176°F).temperature sensor (Even if the sensor signal becomes normal again, the control is continued
until the ignltlon
switch is turned off.)
Camshaft position Simultaneous injection of fuel is executed for all cylinders. (In this \
case, the
No.1 cylinder top
sensor dead center is not detected at all after the ignition key is turned on.)\
Barometric pressure The control is executed with the pressure regarded as 760 mmHg
(30
in.Hg).
sensor
Oxygen sensor Closed loop control of the air/fuel mixture ratio is not executed.
i
READ OUT OF DIAGNOSTIC TROUBLE CODE
Precautions for operation
(1) When battery voltage is low, no detection of failure is possible. Be sure to check the battery for voltage and
other conditions before starting the test.
(2) On-board diagnostic item is erased if the battery or the engine control module connector is discon-
nected. Do not disconnect the battery before the di-
agnostic result is completely read.
Using Scan Tool
(1) Switch OFF the ignition switch.
(2) Connect the power-source terminal of the scan tool to the
cigarette lighter socket.
(3) Connect the scan tool to the data link connector. (4) Turn ignition switch to ON.
(5) Using the scan tool, read out and make a note of the
on-
board diagnostic output.
(6) Refer to the diagnostic chart, and repair the indicated loca-
tion of malfunction.
(7) Erase the diagnostic trouble code. (Refer to
P.13-17.)
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FUEL SYSTEM - Troubleshooting 13-17
\ I\-\\\\\\6FUO807
Using Voltmeter
(1) Connect an analog-type voltmeter between the ground/
terminal and the on-board diagnostic output terminal of the
data link connector.
(2) Set the ignition switch to the “ON” position.
(3) Make a note of the pattern of the on-board diagnostic out- put indicated by the voltmenter’s indicator.
(4) Refer to the diagnostic chart, and repair the indicated loca- tion of malfunction.
(5) Erase the diagnostic trouble code.
On-board
diagnostic
output
terminal
LGround
EbLbtR MEMORY OF DIAGNOSTIC TROUBLE
If the Scan Tool is Used
Connect the scan tool to the data link connector, and then
erase by following the steps below.)
(1) To erase diagnostic trouble code for the engine coolant
temperature sensor or idle speed control motor positionsensor, first turn the ignition switch OFF once and then ON
(2) EE?$t
“4. SPECIAL TEST” of the scan tool’s function-select
menu.
(3) Then select item No.5, “ERASE DIAG.“.
(4) If “ERASE DIAG. CODE?” is displayed, press the “YES” k\
ey.
(5) Input ID code “19”.
(6) When “FINISHED ERASING DIAG. CODE” is displayed,> Ipress the “CLEAR” key.
(7) Read out the on-board diagnostic output and check to be
sure that the correct code is being output.
If the Scan Tool is not Used
(1) Turn the ignition switch to OFF.
(2) Disconnect the ground cable from the battery terminal forten seconds or longer, and then reconnect it.
(3) Read out the on-board diagnostic output and check to be
sure that the correct code is being output.
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13-18
FUEL SYSTEM - Troubleshooting
CHECK CHART CLASSIFIED BY PROBLEM SYMPTOMS
:heck items
GR solenoid uel pressure
@El@lEloEloElom
0: W

arm engine (Figures inside the
0 indicate the checking sequence.)0: Cold engine (Figures inside the
q indicate the checking sequence.)
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13-32
FUEL SYSTEM - Troubleshooting/Service Adjustment Procedures
FUEL TANK AND FUEL LINEMlBEAAA
Symptom Probable cause Remedy
Engtne malfunctions
Bent or kinked fuel pipe or hose Repair or replace3ue to insufficient fuel
SUPPlYClogged fuel pipe or hoseClean or replace
Clogged fuel filter or in-tank fuel filter Replace
Water in fuel filter Replace the fuel filter or clean the fuel tank
and fuel line
Dirty or rusted fuel tank interior Malfunctioning fuel pump
(Clogged filter in the pump) Clean or replace
Replace
Evaporative emission Mispiping of vapor line
Correct
control system malfunc-
tions (When fuel tank Disconnect vapor line piping joint Correct
filler tube cap is re- moved, pressure releas-
Folded, bent, cracked or clogged vapor line Replace
ng noise is heard) Faulty fuel tank filler tube cap
Malfunctioning fuel tank pressure control
valve Replace
Replace
LL
m ~~ : Paper clip-
F l!;“I /yFp- -
izd--_7-01
A0086SERVICE ADJUSTMENT PROCEDURES
CURB IDLE SPEED INSPECTION
MlBFHAFt
(1) The vehicle should be prepared as follows before the inspection.
lEngine coolant temperature: 85-95°C (185-203°F)
l Lights, electric cooling fan and accessories: OFF
l Transaxle: Neutral
(P for vehicles with an automatic
transaxle)
(2) Connect a tachometer or connect the scan tool to the data
link connector.
NOTE
Refer to
P.13-33 for information concerning connection Of
a tachometer.
(3) Set a timing light in position.
(4) Ground the terminal for adjustment of ignition timing.
(5) Start the engine and let it idle.
(6) Check whether or not the ignition timing is the standard
value; if not, adjust.
Standard value:
5”BTDC + 2”
(7) Stop grounding the terminal for adjustment of ignition timing. .
(8) Let the engine idle for two minutes.
(9) Check the idling rpm.
Curb idle speed:
7502 100 rpm
NOTE
The idling rpm is automatically regulated by the idle-speed control system.
1
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FUEL SYSTEM -Service Adjustment Procedures 13-33
For a female
pin
For a male pin
(insert at side (Insert at lock tab side.,
opposite from lock tab.)
OlLO246
(10)lf not within the standard value range, refer to the CHECK
CHART CLASSIFIED BY PROBLEM SYMPTOMS and check the
MFI component.
BASIC IDLE SPEED ADJUSTMENT
MlBFHBA
(1) The vehicle should be prepared as follows before the inspection and adjustment.
l Engine coolant temperature:
85-95°C (185-205°F)
l Lights, electric cooling fan and accessories: OFF
l Transaxle: Neutral
(P for vehicles with an automatic
transaxle)
(2) Slacken the accelerator cable enough.
(3) Connect the scan tool to the data link connector (white).
(4) If the scan tool is not used, follow the steps below.
@I Insert a paper clip (from the harness side) into the l-pin connector shown in the figure at the left.
Take care not to disconnect the connector.
Caution
The paper clip should be inserted between the
terminals as shown in the figure at the left., @ Connect a primary-voltage-detection type of tacho-
meter to the paper clip.
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