Mitsubishi Lancer Evolution IX. Manual - part 466

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-339

STEP 22. Connector check: C-121 engine-ECU 
connector.

Q: Is the check result normal? 

YES : 

Check intermediate connectors A-29*

1

 or 

C-31*

2

, and repair if necessary. If 

intermediate connectors are normal, check 
and repair harness between A-07X (terminal 
No. 3) condenser fan relay (high) connector 
and C-121 (terminal No. 30) engine-ECU 
connector.

• Check power supply for open circuit 

and damage.

NO : 

Repair or replace the connector.

STEP 23. Perform voltage measurement at A-34 
condenser fan motor connector.

• Disconnect connector, and measure at harness 

side.

• Disconnect C-121 engine-ECU connector, and 

earth terminal No. 30.

• Ignition switch: "ON"

AK501995

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35

1

10

AB

Connector: C-121

C-121 (GR)

C-121 (GR)

Harness side connector

<L. H. drive vehicles>

<R. H. drive vehicles>

AK305267

2

1

3

4

A-07X

Connector: A-07X

AB

Harness side
connector

Relay box’s
triangle marks

AK305266

1

2

A-34(B)

AB

Harness side 
connector

Connector: A-34

AK305267

2

1

3

4

A-07X

Connector: A-07X

AB

Harness side
connector

Relay box’s
triangle marks

AK501995

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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-340

• Voltage between terminal No. 2 and earth.

OK: System voltage

Q: Is the check result normal?

YES : 

Go to Step 24 .

NO : 

Check intermediate connectors A-29*

1

 or 

C-31*

2

, and repair if necessary. If 

intermediate connectors are normal, check 
and repair harness between A-07X (terminal 
No. 3) condenser fan relay (high) connector 
and C-121 (terminal No. 30) engine-ECU 
connector.

• Check power supply for open circuit 

and damage.

STEP 24. Connector check: A-34 condenser fan 
motor connector.

Q: Is the check result normal? 

YES : 

Go to Step 25 .

NO : 

Repair or replace the connector.

STEP 25. Check harness between A-07X 
(terminal No. 3) condenser fan relay (high) 
connector and C-121 (terminal No. 30) 
engine-ECU connector.

NOTE: Before checking harness, check intermediate 
connector A-29*

1

 or C-31*

2

, and repair if necessary.

• Check output line for damage.

Q: Is the check result normal? 

YES : 

Go to Step 26 .

NO : 

Repair the damaged harness wire.

AK305266

1

2

A-34(B)

AB

Harness side 
connector

Connector: A-34

AK305267

2

1

3

4

A-07X

Connector: A-07X

AB

Harness side
connector

Relay box’s
triangle marks

AK501995

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3

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30

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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-341

STEP 26. Connector check: A-35 condenser fan 
motor connector.

Q: Is the check result normal? 

YES : 

Go to Step 27 .

NO : 

Repair or replace the connector.

STEP 27. Perform resistance measurement at 
A-35 condenser fan motor connector.

• Disconnect connector, and measure at harness 

side.

• Resistance between terminal No. 2 and earth.

OK: 2 

Ω or less

Q: Is the check result normal? 

YES : 

Replace the engine-ECU.

NO : 

Repair the damaged harness wire.

Inspection Procedure 27: A/C Switch System

AK305443

1

2

A-35(GR)

AB

Harness side 
connector

Connector: A-35

AK305443

1

2

A-35(GR)

AB

Harness side 
connector

Connector: A-35

AK501832

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83

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100

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78

71

90

76 77

75

72
79

P

Engine-ECU

83

A/C-ECU

A/C Switch circuit

C-117

(MU803783)

AB

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

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-342

OPERATION

• The battery voltage is applied to the engine-ECU 

(terminal No. 83) from the A/C-ECU (terminal No. 
1).

FUNCTION

• When the A/C switch is in "ON" position, A/C 

switch ON signal is inputted to the engine-ECU 
from the A/C-ECU. In response to the signal, the 
engine-ECU controls the A/C compressor relay.

PROBABLE CAUSES

• Failed A/C

• Failed A/C system

• Open/short circuit in A/C circuit or loose connec-

tor contact

• Failed engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. Perform voltage measurement at C-117 
engine-ECU connector.

• Measure engine-ECU terminal voltage.

• 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

• Voltage between terminal No. 83 and earth.

OK: 

System voltage (when A/C is ON)
0.5 V or less (when A/C is OFF)

Q: Is the check result normal?

YES : 

Go to Step 2 .

NO : 

 Check A/C system (Refer to GROUP 55 

− 

Troubleshooting 

− Check Chart for Trouble 

Symptoms 

P.55-29

)

AK501996

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87

81

94

85

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93

86

98

99

74

92

73

83

88

91

95

97 96

100

89

78

71

90

76

77

75

72
79

AB

Connector: C-117

C-117 (GR)

C-117 (GR)

Harness side connector

<L. H. drive vehicles>

<R. H. drive vehicles>