1989 MITSUBISHI GALANT Service Repair Manual

FUEL SYSTEM -On-Vehicle Inspection of
MFI Components13-299
OPERATION
l The amount of air taken in during idling is
regulated by the opening and closing of the
servo valve located in the air passage that
bypasses the throttle valve.
l The servo valve is opened or closed by the
activation of the stepper motor (incorporated
within the idle air control motor) in the forward
or reverse direction.
TROUBLESHOOTING HINTS
Hint 1: If the number of stepper motor steps increases to
IOO- 120 steps or decreases
to 0 step, the cause may be presumed to be a malfunction of the stepper motor or
damaged or disconnected wiring of the
harness.
Hint 2: If the number of stepper motor steps
deviates from the standard value even
though the results of the checking of the
harness of the idle air control motor and of
the comoonent
itself indicate no abnormal
condition, the cause may be presumed to be one of the following.
INSPECTION
Using Scan tool
lBattery power supply is supplied, by way of the
multiport fuel injection relay, to the coil of the
stepper motor. The engine control module
switches ON the power transistors (located
within the engine control module) in sequential
order, and, when current flows to the stepper motor coil, the stepper motor is activated in the
forward or reverse direction.
(1) Improper adjustment of the standard
idling speed.
(2) Deposits adhered to the throttle valve.
(3) Leakage of air into the intake manifold
from a gasket gap, etc.
(4) Incomplete close contact of the EGRvalve seat.
(5) Incomplete combustion within the
cylinder.
(Malfunction of the spark plugs, the
ignition coil, the iniectors,
the
com- pression
pressure, etc.)
FunctionItem No.Data display Check conditions Load conditionsStandard value
Data reading 45Steppermotor steps. Engine coolant tempera-
. Air conditioning
4-14Step
ture:switch: OFF 85-95°C

(185-205°F)
. Lights, electrical cooling
:$b::pfan and accessories: OFF
. Transaxle: neutral
. Closed throttle switch: ON
- Air conditioning 20-60 Step
switch: ON
(The compressor clutchshould be activated when
the air conditioning switch;J-;;o~P
is switched ON.)* Engine: idling
1;:!,1;:!,
/!-I\/!-I\
f$&$:”f$&$:”
! ,‘,! ,‘,
4);4);
;jj\(Q(j!jGZ-);jj\(Q(j!jGZ-)
lili
q#Q~Hq#Q~HF]F]
ii 2 L J 2 L ~ -0SClllO 4ii 2 L J 2 L ~ -0SClllO 4
NOTE
When the vehicle is new (driven approximately 500 km (300 miles) or l\
ess) the number of steps may be about
30 steps greater than the standard value indicated above.
Using Oscilloscope
(1) Connect the probe to each oscilloscope pick-up point as
shown in the circuit diagram.
(2) Start the engine.
(3) When the air conditioning switch is turned on, the idling speed increases to operate the idle air control. Check theinstantaneous waveform.
NOTE
Keep in mind that the waveform can be observed only
when idle air control is in operation.

FUEL SYSTEM - On-Vehicle Inspection
of
MFI Components
HARNESS INSPECTION
connector
@ Harness side7
connectorharnessside connw&
cI
7FUOOlO
Measure the power supply VOltage ofthe idle air control motor.
. e Idle air control motor connec-tor: Disconnected. Ignition switch: ON
Check for an open-circuit, or a short-circuit to ground, between the enginecontrol module and idle air controlmotor.
. Engine control module connec-tor: Disconnected* Idle air control motor connec-‘--R&heharness.tor: Disconnected
ACTUATOR INSPECTION
Checking the Operation Sound
(1) Check that the operation sound of the stepper motor can
be heard after the ignition is switched ON (but without
starting the motor).
(2) If the operation sound cannot be heard, check the stepper
motor’s activation circuit.If the circuit is normal, it is probable that there is a
malfunction of the stepper motor or of the engine control
module.
Checking the Coil Resistance
(1) Disconnect the idle air control motor connector and con- nect the special tool (Test harness).
(2) Measure the resistance between terminal
@ (white clip of
the special tool) and either terminal
@ (red clip) or terminal
$d;!lue clip) of the connector at the idle air control motor
Standard value: 28-33 &
at
20°C (68°F)
(3) Measure the resistance between terminal @ (green clip of
the special tool) and either terminal
@ (yellow clip) or ter-
minal
@ (black clip) of the connector at the idle air control
motor side.
Standard value: 28-33
51 at 20°C (68°F)
J
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FUEL SYSTEM - On-Vehicle
lnsoection
of MFI
ComDonents13-301
<:I989models> d
\’ @
ml
Idle aircontrol motor
10 /(stepper motor)
w-6FUO609
1990 models>
6FU1426L
MD9984f \
7FUOOlli
Operational Check
(1) Remove the throttle body.
(2) Remove the stepper motor
(3) Connect the special tool (Test harness) to the idle air con- trol motor connector.
(4) Connect the positive (+) terminal of a power supply
(approx. 6
V) to the white clip and the green clip.
(5) With the idle air control motor as shown in the illustration, connect the negative (-)
terminal of the power supply to
each clip as described in the following steps, and check
whether or not a vibrating feeling (a feeling of very slight
vibration of the stepper motor) is generated as a result of
the activation of the stepper motor. @ Connect the negative
(-) terminal of the power supply
to the red and black clip.
@ Connect the negative (-) terminal of the power supply
to the blue and black clip. @ Connect the negative
(-) terminal of the power supply
to the blue and yellow clip.
@I Connect the negative (-) terminal of the power supply
to the red and yellow clip. @ Connect the negative
(-) terminal of the power supply
to the red and black clip. @ Repeat the tests in sequence from (5) to
(1).
(6) If, as a result of these tests, vibration is detected, the
stepper motor can be considered to be normal.
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13-302FUEL SYSTEM - On-Vehicle Inspection
of MFI
Components
IGNITION COIL AND IGNITION POWER TRANSISTOR

Batterv
tm3wAAa
@ Harness sideconnector
@ Harness sideconnector
/gnition, coil ,fz ,
,
5EL1401/
fY@gT$J p$=ppt.~~or JJ$& Spark
7b b b APlug
Engine control module connector
2 q$gFQ%y@TgLQIgnitionNo 2 No.3 No 4 No 1
tlmlng
adjustment
0
connecfor
31 E$;control
01 LO838
OPERATION
l When ignition power transistor unit A i

s
switched ON by signals from the engine control module, primary current flows to ignition coil A.
When ignition power transistor unit A is
switched OFF, the primary current is inter-
rupted, high voltage is generated at secondary
coil A, and the spark plug for the
No.1 and No.4
cylinders sparks. When, however, ignition
power transistor unit
6 is switched from ON to
OFF, the spark plug for the
No.2 and No.3 cylin-
ders sparks.
lWhen the engine control module switches OFF
the power transistor inside the unit, battery vol-
tage is applied to the ignition power transistor unit, and the ignition power transistor unit is
switched ON.
When the engine switches ON the ignition power transistor within the unit, however, the
ignition power transistor unit is switched OFF.
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r
FUEL SYSTEM -On-Vehicle Inspection
of
MFI Components13-303
INSPECTION
Using Scan tool
Function Item No.
Data reading 44
Data displayInspection conditionsEngine condition Standard value
Ignition
advance
. Engine: warm
. Timing light: set750 rpm (idling)5-15” BTDC
(Use the timing light to
check the actual ignition 2,000 rpm32 - 4 1 “BTDCtiming.)
Oscillo 1
Normal waveform
Oscilio 2
!
1ov --
-
ovNormal waveform
HARNESS INSPECTION
Harness side
connectorE 0-0
J
El0
connectorI
lEnginecontrol
module
harness
sideconnector
Using Oscilloscope
1. Primary signal of ignition coil
(1) Run the engine at an idle revolution speed.
(2) Connect the probe to oscilloscope pick-up point
1 as
shown in the circuit diagram, and check the primary
signal of the ignition coil.
2.Control signal of ignition power transistor
(3) Connect the probe to oscilloscope pick-up point 2 as
shown in the circuit diagram, and check the control
signal of the ignition power transistor.
Measure the power supply voltage ofthe ignition coil.
. Connector: Disconnected. Ignition switch: ON
Voltage (VI
IBattery positive voltageIIIgnitionswitch)
Check for an open-circuit, or a
short-circuit to ground, between the engine
control module and the ignition coil.
* Engine control module connec- tor: Disconnected
* Ignition coil connector: Discon-nected
i
Repair theharness.
N23l3k-m)
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13-304FUEL SYSTEM - On-Vehicle
Inspection
of MFI
Components
Harness side
connector
Check for an open-circuit, or a short-circuit to around, between the iani- ~
tion power transistor and the ignisoncoil
.
* ignition coil connector: Discon-netted. Ignition power transistor connec-tor: Disconnected
Harness side
6FU1381
Harness side@ connector
+-
6FU1382
Ignition timing
adjustmentI’ 7l-i---3connector
0 l-
t!-
:6FU1287
ACTUATOR INSPECTION
Refer to GROUP 16-Ignition System.
I
Check for continuity of the groundcircuit.
‘. Connector: Disconnected
cl5
Repair theharness.
KBEil-Ground)
Measure the voltage of the control
signal circuit of the ignition power
transistor.
* Ignition power transistor connec-tor: Disconnected. Ignition switch: START
Measure the voltage of the ignition
timing adjustment terminal.
. Ignition switch: ON
Voltage (V)
1 4.0-5.2 1Repair theharness.
KaIl--~)
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FUEL SYSTEM -On-Vehicle Inspection
of MFI
Components13-305
IGNITION COIL AND IGNITION POWER TRANSISTOR
Ml3WAAb
@ Harness sideconnector
@ Harness sideconnector
5EL13031
@ Component sideconnector
15EL1700
Battery
@CompmntStde con-
control
module
a
Spark
PlUGI .-
'. 1
Enoine
Engine control module connector
OPERATION
INSPECTION
Using Scan tool
Refer to P.13-302.
cm
i
Function Item No.
Data displayInspection conditionsEngine condition Standard valueI
reading445- 15” BTDC
BTDC ) BTDC
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13-306FUEL SYSTEM - On-Vehicle
Inspection
of
MFI
Components
Harnesscirio
-.-.,@ connector
Measure the power supply voltage ofthe ignition coil.
. Connector: Disconnected. Ignition switch: ON
HARNESS INSPECTION
Harness side
I
Measure the power supply voltage ofthe ignition coil.
. Connector: Disconnected. ignition switch: ON
control module and the ignition
power transistor.
. Engine control module connec-tor: Disconnected. Ignition power transistor connec-tor: DisconnectedRepair theharness.
KI3zil-m)
6FU1387I
t III1an open-circuit, or a short-ground, between the igni-
power transistor and the ignition
coil connector: Discon-
* Ignition power transistor connec-tor: DisconnectedReoair the
t
hamess.
KBEI-GUI~GZWBXZl)
IJ
5
Harness side@ connector
J
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Check for continuity of the groundcircuit.
. Connector: Disconnected