Mitsubishi Lancer Evolution IX. Manual - part 456

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-299

STEP 4. Perform voltage measurement at C-121 
engine-ECU connector.

• Disconnect connector, and measure at harness 

side.

• Ignition switch: "ON"

• Voltage between terminal No. 18 and earth.

OK: 4.9 

− 5.1 V

Q: Is the check result normal?

YES : 

Replace the fan controller.

NO : 

Go to Step 5 .

STEP 5. Connector check: A-17 fan controller 
connector

Q: Is the check result normal?

YES : 

Go to Step 6 .

NO : 

Repair or replace the connector.

STEP 6. Check harness between A-17 (terminal 
No. 2) fan controller connector and C-121 
(terminal No. 18) engine-ECU connector.

NOTE: Before checking harness, check intermediate 
connector A-13*

1

 or 31*

2

, and repair if necessary.

• Check output line for open circuit.

Q: Is the check result normal?

YES : 

Replace the fan controller.

NO : 

Repair the damaged harness wire.

AK501995

2

3

4

5

6

7

8

9

11

12

13

14

15

16

17

18

19

20

30

21

22

23

24

25

26

27

28

29

31

32

33

34

35

1

10

AB

Connector: C-121

C-121 (GR)

C-121 (GR)

Harness side connector

<L. H. drive vehicles>

<R. H. drive vehicles>

AK305256

1

2

3

AB

Connector: A-17

A-17 (GR)

Harness side connector

AK305256

1

2

3

AB

Connector: A-17

A-17 (GR)

Harness side connector

AK501995

2

3

4

5

6

7

8

9

11

12

13

14

15

16

17

18

19

20

30

21

22

23

24

25

26

27

28

29

31

32

33

34

35

1

10

AB

Connector: C-121

C-121 (GR)

C-121 (GR)

Harness side connector

<L. H. drive vehicles>

<R. H. drive vehicles>

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-300

Inspection Procedure 22: Poor A/C Performance

COMMENT ON TROUBLE SYMPTOM

• Failure is possibly caused by short /overcharged 

A/C refrigerant, failed A/C control system, failed 
fan control system or other faults.

PROBABLE CAUSES

• Short or overcharged A/C refrigerant

• Failed A/C compressor

• Failed fan controller

• Failed A/C-ECU

• Failed engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-II/III diagnosis code

Q: Diagnosis code set?

YES : 

Inspection chart for diagnosis code (Refer 

to 

P.13A-17

).

NO : 

Go to Step 2 .

STEP 2. A/C compressor magnet clutch 
operation check.

• Engine: Idling

• A/C set temperature:

Maximum Cool when temperature in cabin is 

25

°C or more

Maximum Hot when temperature in cabin is 25

°C 

or less

OK:

Magnet clutch active (when A/C is ON)
Magnet clutch inactive (when A/C is OFF)

Q: Is the check result normal? 

YES : 

Go to Step 5 .

NO : 

Go to Step 3 .

STEP 3. M.U.T.-II/III data list

• Item No. 28: A/C switch

a. Engine: Idling
b. A/C set temperature:

Maximum Cool when temperature in cabin is 

25

°C or more

Maximum Hot when temperature in cabin is 

25

°C or less

OK: 

ON (when A/C is ON)
OFF (when A/C is OFF)

Q: Is the check result normal?

YES : 

Go to Step 4 .

NO : 

Check A/C switch (Refer to Inspection 
Procedure 27 

P.13A-341

).

STEP 4. M.U.T.-II/III data list

• Item No. 49: A/C relay

a. Engine: Idling
b. A/C set temperature:

Maximum Hot when temperature in cabin is 

25

°C or less

Maximum Cool when temperature in cabin is 

25

°C or more

OK: 

ON (when A/C is ON)
OFF (when A/C is OFF)

Q: Is the check result normal?

YES : 

Check A/C system (Refer to GROUP 55 

− 

Troubleshooting 

P.55-29

).

NO : 

Check A/C compressor relay (Refer to 
Inspection procedure 28 

P.13A-344

).

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-301

STEP 5. Check charged amount of A/C 
refrigerant.

• Check charged amount of A/C refrigerant (Refer 

to GROUP 55 

− On-vehicle Service 

P.55-104

).

Q: Is the check result normal?

YES : 

Go to Step 6 .

NO : 

Adjust charged amount of A/C refrigerant.

STEP 6. M.U.T.-II/III actuator test

• Item No. 21: Fan controller

OK: Fan motor rotates.

Q: Is the check result normal?

YES : 

Check A/C load signal system (Refer to 

Inspection Procedure 29 

P.13A-352

).

NO : 

Check radiator fan control relay system 
(Refer to Inspection Procedure 25 

P.13A-324

).

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-302

Inspection Procedure 23: Engine-ECU Power Supply, Engine Control Relay, Ignition Switch-IG1 
System

1

2

3

4

AK501828

1 2 3
4 5 6

65

43
50

42
49

41
48
60 61

64

46 47
58 59
67 68

45

56
66

52

51

44

53

62

54

63

57

55

80

87

81

94

85

82

84

93

86

98

99

74

92

73

83

88

91

95

97

96

100

89

78

71

90

76 77

75

72
79

R

IG2

ST

LOCK

ACC

IG1

8

20A

8

7.5A

Battery

C-208

Ignition switch

2

1

4

J/B

99

60

Engine
control
relay

B-12X

28

31

30

57

Back-up

power supply

59

47

46

58

Power
supply

Engine-ECU

Relay box

W

B-Y

B-Y

B-Y

R-Y

B-R

R-B

B-W

R-Y

R-Y

R

Power supply and ignition switch-IG circuit

Wire colour code
B: Black  LG: Light green  G: Green  L: Blue  W: White  Y: Yellow  SB: Sky blue  BR: Brown  O: Orange  GR: Gray
R: Red  P: Pink  V: Violet  PU: Purple

AB

W

6 <A-13> (*1) or
13 <C-31> (*2)

1

2

4

3

L (*1) or
B-W (*2)

J/C (6)
C-105

C-119

(MU803782)

C-117

(MU803783)

B

B

NOTE

*1: L.H. drive vehicles
*2: R.H. drive vehicles

B

C-210

C-123

6

C-211