Mitsubishi Lancer Evolution IX. Manual - part 467

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-343

STEP 2. Connector check: C-117 engine-ECU 
connector

Q: Is the check result normal?

YES : 

Go to Step 3 .

NO : 

Repair or replace the connector.

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 : 

Intermittent malfunction (Refer to GROUP 

00 

− How to Use 

Troubleshooting/Inspection Service Points 

P.00-5

).

NO : 

Replace the engine-ECU.

AK501996

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

AB

Connector: C-117

C-117 (GR)

C-117 (GR)

Harness side connector

<L. H. drive vehicles>

<R. H. drive vehicles>

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-344

Inspection Procedure 28: A/C Compressor Relay System

3

4 5 6

1 2

1

2

3

4

1

AK501833

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

3132 33

34 35

1

10

R

IG2

ST

LOCK

ACC

IG1

5

7.5A

9

10A

L-B

W-B

W-B

W-B

P

Ignition switch

C-208

4

2

C-211

13

C-210

3<C-124> (

*1) or

1

<C-122> (

*2)

17 (

*1) or 11 

(

*2)

J/C (2)
C-101

14 (

*1) or 8 

(

*2)

J/B

A/C compressor relay

Battery

Relay box

L-G

B-Y

B-Y

L-G

W

W

1

2

A-13 (

*1)

1

1

4

C-31 (

*2)

6

3

B-13X

A-36

MU802653

A/C refrigerant
temperature
switch

A/C compressor
assembly

Magnetic
clutch

4

C-31 (*2)

A-29 (*1)

6

A/C compressor relay Circuit

20

AB

C-121

(MU803784)

Engine-ECU

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

NOTE

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

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-345

OPERATION

• The battery voltage is applied to the A/C com-

pressor relay (terminal No. 1).

• The battery voltage is applied to the A/C com-

pressor relay (terminal No. 2) from the ignition 
switch. The engine-ECU (terminal No. 20) makes 
the power transistor in the unit be in "ON" posi-
tion and makes currents go on the A/C compres-
sor relay coil, and that makes the relay be in "ON" 
position.

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

battery voltage is supplied to the A/C compressor 
(terminal No. 4) from the A/C compressor relay 
assembly (terminal No. 1).

FUNCTION

• When the A/C switch "ON" signal is input to the 

engine-ECU, the engine-ECU places the A/C 
compressor relay in the "ON" position. Accord-
ingly, the battery voltage supplied to the A/C com-
pressor operates the magnet clutch.

PROBABLE CAUSES

• Failed A/C compressor relay

• Failed A/C compressor magnet clutch

• Open/short circuit in A/C compressor relay circuit 

or loose connector contact

• Failed engine-ECU

DIAGNOSIS PROCEDURE

NOTE: 

.

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

STEP 1. Connector check: B-13X A/C 
compressor relay connector

Q: Is the check result normal?

YES : 

Go to Step 2 .

NO : 

Repair or replace the connector.

STEP 2. A/C compressor relay check.

• Check A/C compressor relay (Refer to GROUP 

55 

− On-vehicle Service − Power Relay Check 

P.55-107

).

Q: Is the check result normal?

YES : 

Go to Step 3 .

NO : 

Replace the A/C compressor relay.

STEP 3. Perform voltage measurement at B-13X 
A/C compressor relay connector.

• Remove relay, and measure at relay box side.

• Ignition switch: "ON"

• Voltage between terminal No. 2 and earth.

OK: System voltage

Q: Is the check result normal?

YES : 

Go to Step 5 .

NO : 

Go to Step 4 .

AK305270

2

1

3

4

B-13X

Connector: B-13X

AB

Harness side
connector

Relay box’s
triangle marks

AK305270

2

1

3

4

B-13X

Connector: B-13X

AB

Harness side
connector

Relay box’s
triangle marks

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-346

STEP 4. Connector check: C-208 ignition switch 
connector

Q: Is the check result normal?

YES : 

Check intermediate connectors C-124

*1

or 

C-122

*2

, C-210 and C-211, and repair if 

necessary. If intermediate connectors are 
normal, check and repair harness between 
B-13X (terminal No. 2) A/C compressor 
relay connector and C-208 (terminal No. 4) 
ignition switch connector.

• Check power supply line for 

open/short circuit.

NO : 

Repair or replace the connector.

STEP 5. Perform voltage measurement at B-13X 
A/C compressor relay connector.

• Remove relay, and measure at relay box side.

• Voltage between terminal No. 1 and earth.

OK: System voltage

Q: Is the check result normal?

YES : 

Go to Step 6 .

NO : 

Check intermediate connector A-29

*1

or 

C-31

*2

, and repair if necessary. If 

intermediate connector is normal, check and 
repair harness between B-13X (terminal No. 
1) A/C compressor relay connector and 
battery.

• Check power supply line for 

open/short circuit.

STEP 6. Connector check: A-36 A/C compressor 
assembly connector

Q: Is the check result normal?

YES : 

Go to Step 7 .

NO : 

Repair or replace the connector.

AK305251

1

2

3

4

5

6

Harness side connector

Connector: C-208

C-208

<L. H. drive vehicles>

<R. H. drive vehicles>

C-208

AB

AK305270

2

1

3

4

B-13X

Connector: B-13X

AB

Harness side
connector

Relay box’s
triangle marks

AK305270

2

1

3

4

B-13X

Connector: B-13X

AB

Harness side
connector

Relay box’s
triangle marks

AK502005

1

AB

Connector: A-36

Harness side 
connector

A-36 (B)