Mitsubishi Galant. Manual — part 291

MULTIPORT FUEL INJECTION(MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.0L>

13B-389

STEP 1. Using scan tool MB991502, read the A/T
diagnostic trouble code (DTC).

CAUTION

To prevent damage to scan tool MB991502, always turn the
ignition switch to the "LOCK"(OFF) position before
connecting or disconnecting scan tool MB991502.
(1) Connect scan tool MB991502 to the data link connector.
(2) Turn the ignition switch to the "ON" position.
(3) Check the A/T-DTC.
(4) Turn the ignition switch to the "LOCK"(OFF) position.

Q: Is the A/T-DTC is output?

YES : Refer to GROUP 23A, Automatic Transaxle

Diagnosis

−

Diagnostic Trouble Code Chart(

P.23A-

37

).

NO : If DTC P1751 is output again after the MFI-DTC has

been erased, replace the PCM. Then check that the
DTC P1751 does not reset.

AC003081 AB

16 PIN

MB991502

MULTIPORT FUEL INJECTION(MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.0L>

13B-390

SYMPTOM PROCEDURES

INSPECTION PROCEDURE 1: Communication with Scan Tool Is Not Possible. (Comunication with All
Systems Is Not Possible.)

AK000519

1

RED

RED

RED-BLA

CK

BLA

CK

BLA

CK

BLA

CK

FUSIBLE LINK(1)

C-85

DATA LINK
CONNECTOR

38

1

18

16

4

5

JUNCTION
BLOCK

15 16

26 27 28 29

32 33 34

17 18 19 20 21 22 23 24 25

30 31

36 37

35

38

10

11 12 13

1 2 3

4 5 6 7 8 9

14

C-66

1

6

4

5

11

10

12 13

15

17

16

14

19

18

8 9

7

20

2 3

C-78
MU801457

15

14

13

12

11

10

1 2 3 4 5 6 7 8
9

16

C-23

ACX02447

CONNECTOR:C-23

ACCELERATOR
PEDAL

DATA LINK
CONNECTOR

AH

AK000561

CONNECTOR:C-85

AB

MULTIPORT FUEL INJECTION(MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.0L>

13B-391

CIRCUIT OPERATION

•

A battery positive voltage is applied on the data
link connector power terminal (terminal 16). The
ground terminals (terminal 4, 5) are grounded to
the vehicle body.

COMMENT

•

The cause is probably a defect in power supply
system (including ground) for the on-board
diagnostic test mode line.

TROUBLESHOOTING HINTS (The most likely
causes for this case:)

•

Malfunction of the data link connector.

•

Damaged harness wire.

DIAGNOSIS

STEP 1. Check the power supply voltage at data link
connector C-23.
(1) Measure voltage between terminal 16 and ground.

•

Voltage should be battery positive voltage.

Q: Is the voltage normal?

YES : Go to step 2.
NO : Check harness connectors C-66, C-78 and C-85 at

intermediate connector for damage, and repair or
replace as required. Refer to GROUP 00E, Harness
Connector Inspection(

P.00E-2

). If intermediate

connectors are in good condition, repair harness wire
between fusible link (1) and data link connector C-23
terminal 16 because of open circuit. Then confirm that
the malfunction symptom is eliminated.

STEP 2. Check the continuity at data link connector C-23.
(1) Check for the continuity between terminal 4, 5 and ground.

•

Should be less than 2 ohm.

Q: Is the continuity normal?

YES : Replace the scan tool. Then confirm that the

malfunction symptom is eliminated.

NO : Repair harness wire between data link connector C-

23 terminal 4, 5 and ground because of open circuit or
harness damage. Then confirm that the malfunction
symptom is eliminated.

AK000631AB

CONNECTOR:C-78

AK000632 AB

CONNECTOR:C-66

AKX01430

1 2 3 4

121314

6

5

7 8

16

15

11

10

9

C-23 HARNESS
SIDE CONNECTOR

AE

AKX01431

AKX01431

1 2 3 4 5 6 7 8

16

15

14

13

12

11

10

9

C-23 HARNESS
SIDE CONNECTOR

AD

MULTIPORT FUEL INJECTION(MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.0L>

13B-392

INSPECTION PROCEDURE 2: Scan Tool Communication with PCM Is Not Possible.

AK000520

GRA

Y

-

RED

GRA

Y

-

RED

GRA

Y

-

RED

RED-

WHITE

RED-

WHITE

RED-

WHITE

POWERTRAIN CONTROL
MODULE(PCM)

JOINT
CONNECTOR(1)

DATA LINK
CONNECTOR

1

30

33

9

10

15

12

7

84

85

C-17

7 8

5

3 4

35

34

10 11 12

2122 23 24

13 14 15

25 26 27

16

28

17

18 19 20

29

30 31

32 33

36 37

38

9

1 2

6

C-57

16

15

18

17

14

20

22

21

9

7

1 2

5

19

3

33

32

30 31

29

28

25

24

23

27

26

6

11

13

4

10

8

12

C-23

15

14

13

12

11

10

1 2 3 4 5 6 7 8
9

16

98

78

71

88 89

76 77

72
79
91

73
80

74

75

81
92

82 83
93

84 85

94

86 87

95 96

90

97

C-41
(MU803782)

ACX02447

CONNECTOR:C-23

ACCELERATOR
PEDAL

DATA LINK
CONNECTOR

AH

AK000633 AB

CONNECTOR:C-57