Mitsubishi Galant. Manual — part 191

ON-VEHICLE SERVICE

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <2.4L>

13A-445

Check using oscilloscope
1. Disconnect the throttle position sensor connector and

connect the test harness special tool (MB991348) in
between.(All terminals should be connected.)

2. Connect the oscilloscope probe to the throttle position

sensor side connector terminal 3.

3. Turn the ignition switch "ON" position.

4. Slowly move the throttle lever from the idle position to the

full-throttle position and check then if the waveform is free
from any noise.

5. If any noise is recognized, replace the throttle position

sensor.

NOTE: After replacement, the throttle position sensor should
be adjusted. (Refer to

P.13A-437

.)

HEATED OXYGEN SENSOR CHECK

M1131005000099

Required Special Tools:
MB991658: Test Harness Set
MD998464: Test Harness
<Heated oxygen sensor (rear)>
1. Using scan tool MB991502, observe HO

2

S reading. If

values are unsatisfactory, or if Scan tool is not available, use
the following procedure:

(1) Disconnect the heated oxygen sensor connector and

connect special tool MB991658 to the connector on the
heated oxygen sensor side.

(2) Make sure that there is continuity [11-18

Ω

at 20

°

C

(68°

F)] between terminal 3 and terminal 4 on the heated
oxygen sensor connector

(3) If there is no continuity, replace the heated oxygen

sensor.

(4) Warm up the engine until engine coolant is 80

°

C (176

°

F

)

or higher

.

CAUTION

Be very careful when connecting the jumper wires;
incorrect connection can damage the heated oxygen
sensor.

(5) Use the jumper wires to connect terminal 3 of the heated

oxygen sensor connector to the positive battery terminal
and terminal 4 to the negative battery terminal.

(6) Connect a digital voltage meter between terminal 1 and

terminal 2.

2. While repeatedly revving the engine, measure the heated

oxygen sensor output voltage.

AKX01461AB

THROTTLE POSITION
SENSOR CONNECTOR

OSCILLOSCOPE

1 2 3 4

AKX01462AB

NORMAL WAVEFORM

THROTTLE LEVER
FULL-THROTTLE
POSITION

THROTTLE
LEVER
IDLE
POSITION

AK000121AB

HEATED OXYGEN SENSOR
EQUIPMENT SIDE CONNECTOR

MB991658

AK000122

JUMPER
WIRES

MB991658

AB

ON-VEHICLE SERVICE

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <2.4L>

13A-446

Standard value:

3. If the sensor is defective, replace the heated oxygen sensor.

NOTE: For removal and installation of the heated oxygen
sensor, refer to GROUP 15, Exhaust Pipe and Main Muffler
(

P.15-18

).

<Heated oxygen sensor (front)>
1. Using the scan tool MB991502, observe HO

2

S reading. If

values are unsatisfactory, or if Scan tool is not available, use
the following procedure:

(1) Disconnect the heated oxygen sensor connector and

connect special tool MD998464 to the connector on the
heated oxygen sensor side.

(2) Make sure that there is continuity [4.5

−

8.0

Ω

at 20

°

C

(68°

F)] between terminal 1 (red clip of special tool ) and

terminal 3 (blue clip of special tool ) on the heated oxygen
sensor connector

(3) If there is no continuity, replace the heated oxygen

sensor.

(4) Warm up the engine until engine coolant is 80

°

C (176

°

F)

or higher.

CAUTION

Be very careful when connecting the jumper wires;
incorrect connection can damage the heated oxygen
sensor.

(5) Use the jumper wires to connect terminal 1 (red clip) of

the heated oxygen sensor connector to the positive
battery terminal and terminal 3 (blue clip) to the negative
battery terminal.

(6) Connect a digital voltage meter between terminal 2 (black

clip) and terminal 4 (white clip).

2. While repeatedly revving the engine, measure the heated

oxygen sensor output voltage.

Standard value:

ENGINE

HEATED OXYGEN
SENSOR OUTPUT
VOLTAGE

REMARKS

When revving
engine

0.6

−

1.0V

If you make the air/
fuel ratio rich by
revving the engine
repeatedly, a
normal heated
oxygen sensor will
output a voltage of
0.6

−

1.0V.

AKX01624

HEATED
OXYGEN
SENSOR
EQUIPMENT
SIDE
CONNECTOR

MD998464

BLUE

RED

AC

AKX01625AC

BLUE

RED

BLACK

JUMPER
WIRES

WHITE

MD998464

ON-VEHICLE SERVICE

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <2.4L>

13A-447

3. If the sensor is defective, replace the heated oxygen sensor.

NOTE: For removal and installation of the heated oxygen
sensor, refer to GROUP 15, Exhaust Pipe and Main Muffler
(

P.15-18

).

INJECTOR CHECK

M1131005200082

Measurement of Resistance between Terminals

1. Disconnect the injector intermediate connector.

2. Measure resistance between terminals.

Standard value: 13

−−−−

16

Ω

Ω

Ω

Ω

[at 20

°°°°

C (68

°°°°

F)]

3. If not within specification, replace the injector.

4. Install the injector connector

Checking operation sound

Using a stethoscope or long blade screwdriver, check the
operation sound ("tick-tick-tick") of injectors during idling or
during cranking. Check that as the engine speed increases, the
frequency of the operating sound also increases.
1. If the injector you are checking is not operating, you may

hear the operating sound of the other injectors.

2. If no operating sound is heard from the injector that is being

checked, check the injector drive circuit. If there is nothing
wrong with the circuit, a defective injector or powertrain
control module (PCM) is suspected.

IDLE AIR CONTROL MOTOR (STEPPER MOTOR)
CHECK

M1131005400105

Required Special Tool:
MB991709: Test Harness Set

ENGINE

HEATED OXYGEN
SENSOR OUTPUT
VOLTAGE

REMARKS

When revving
engine

0.6

−

1.0V

If you make the air/
fuel ratio rich by
revving the engine
repeatedly, a
normal heated
oxygen sensor will
output a voltage of
0.6

−

1.0V.

AK000602AB

1 2

AK000124 AB

STETHOSCOPE

ON-VEHICLE SERVICE

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <2.4L>

13A-448

Checking the Operation Sound
1. Check that the engine coolant temperature is 20

°

C (68

°

F

)

ορ βελοω.

NOTE: If necessary, you can disconnect the engine coolant
temperature sensor connector and connect the harness-side
of the connector to another engine coolant temperature
sensor that is at 20

°

C (68

°

F) or below

.

2. Check that the operation sound of the stepper motor can be

heard after the ignition is switched ON (but without starting
the motor).

3. 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
powertrain control module (PCM).

Checking the Coil Resistance
1. Disconnect the idle air control motor connector.

2. Measure resistance between terminal 2 and either terminal

1 or terminal 3 of the connector at the idle air control motor
side.

Standard value: 28

−−−−

33

Ω

Ω

Ω

Ω

[at 20

°°°°

C

(68

°°°°

F)]

3. If resistance is not within the standard value, replace the IAC

motor.

4. Measure the resistance between terminal 5 and either

terminal 6 or terminal 4 of the connector at the idle air
control motor side.

Standard value: 28

−−−−

33

Ω

Ω

Ω

Ω

[at 20

°°°°

C (68

°°°°

F)]

5. If resistance is not within the standard value, replace the IAC

motor.

<Operation Check>

1. Remove the throttle body.

2. Remove the idle air control motor.

3. Connect special tool MB991709 to the idle air control motor

connector.

4. Connect the positive (+) terminal of a power supply

(approximately 6 V) to terminal 2 and the terminal 5.

5. Connect the negative (-) terminal of the power supply to

each clip as described in the following steps. Then check
whether or not the stepper motor vibrates slighly as it
operates.

(1) Connect the negative terminal of the power supply to

terminal 1 and terminal 4.

(2) Connect the negative terminal of the power supply to

terminal 3 and terminal 4.

AKX01561

1 2 3
4 5 6

1 2 3
4 5 6

AB

AKX01627AB

TERMINAL 2

IAC MOTOR

TERMINAL 5

MB991709