Mitsubishi Galant 9G. Manual — part 957

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

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DIAGNOSIS

Required Special Tools:

• MB991958: Scan Tool (MUT-III Sub Assembly)

• MB991824: V.C.I.

• MB991827: USB Cable

• MB991910: Main Harness A

• MB991923: Power Plant ECU Check Harness

STEP 1. Using scan tool MB991958, check data list item 13:
Intake Air Temperature Sensor.

CAUTION

To prevent damage to scan tool MB991958, always turn the
ignition switch to the "LOCK" (OFF) position before con-
necting or disconnecting scan tool MB991958.
(1) Connect scan tool MB991958 to the data link connector.
(2) Turn the ignition switch to the "ON" position.

(3) Set scan tool MB991958 to the data reading mode for item

13, Intake Air Temperature Sensor.

• The intake air temperature and temperature shown with

the scan tool should approximately match.

(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the sensor operating properly?

YES : It can be assumed that this malfunction is intermittent.

Refer to GROUP 00, How to Use
Troubleshooting/Inspection Service Points

− How to

Cope with Intermittent Malfunctions

P.00-14

.

NO : Go to Step 2.

STEP 2. Check harness connector B-10 at the intake air
temperature sensor for damage.

Q: Is the harness connector in good condition?

YES : Go to Step 3.
NO : Repair or replace it. Refer to GROUP 00E, Harness

Connector Inspection

P.00E-2

. Then go to Step 11.

AC305412

AB

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

AK303015

2

1

3

4

AB

B-10 (GR)

CONNECTOR: B-10

HARNESS
CONNECTOR:
COMPONENT SIDE

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-129

STEP 3. Check the intake air temperature sensor.

(1) Disconnect the intake air temperature sensor connector

B-10.

(2) Measure the resistance between intake air temperature

sensor side connector terminal No. 1 and No. 4.

• There should be continuity. (0.30 − 20 kΩ)

Q: Is the measured resistance between 0.30 and 20 k

Ω?

YES : Go to Step 4.
NO : Replace the mass airflow sensor. Then go to Step 11.

STEP 4. Measure the sensor supply voltage at intake air
temperature sensor harness side connector B-10.

(1) Disconnect the connector B-10 and measure at the harness

side.

(2) Turn the ignition switch to the "ON" position.

(3) Measure the voltage between terminal No. 1 and ground.

• Voltage should be between 4.5 and 4.9 volts.

(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the measured voltage between 4.5 and 4.9 volts?

YES : Go to Step 8.
NO : Go to Step 5.

AK303015

2

1

3

4

AB

B-10 (GR)

CONNECTOR: B-10

HARNESS
CONNECTOR:
COMPONENT SIDE

1

2

3 4

AK203041

INTAKE AIR TEMPERATURE
SENSOR CONNECTOR

AB

AK303015

2

1

3

4

AB

B-10 (GR)

CONNECTOR: B-10

HARNESS
CONNECTOR:
COMPONENT SIDE

AK303034

2

1

3

4

B-10 HARNESS
CONNECTOR:
COMPONENT SIDE

AB

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-130

STEP 5. Measure the sensor supply voltage at PCM
connector B-22 by using power plant ECU check harness
special tool MB991923.

(1) Disconnect the all PCM connectors and connect power

plant ECU check harness special tool MB991923 between
the separated connectors.

(2) Disconnect the intake air temperature sensor connector

B-10.

(3) Turn the ignition switch to the "ON" position.

AK303016

104

96

94

95

93 92 91

99 98 97

103 102 101 100

108 107 106 105

113 112 111 110 109

CONNECTOR: B-22

B-22 (B)

PCM

AB

HARNESS CONNECTOR:
COMPONENT SIDE

AIR CLEANER

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

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(4) Measure the voltage between terminal No. 107 and ground.

• Voltage should be between 4.5 and 4.9 volts.

(5) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the measured voltage between 4.5 and 4.9 volts?

YES : Go to Step 6.
NO : Go to Step 7.

AK202956

104

96

94

95

93 92 91

99 98 97

103 102 101 100

108 107 106 105

113 112 111 110 109

AB

POWER PLANT ECU
CHECK HARNESS CONNECTOR

MB991923

PCM

104

96

94

95

93 92 91

99 98 97

103 102 101 100

108 107 106 105

113 112 111 110 109

AK203043AB

POWER PLANT ECU
CHECK HARNESS
CONNECTOR