Mitsubishi Lancer Evolution IX. Manual - part 470

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-355

STEP 7. Check harness between C-37 (terminal 
No. 32) A/C-ECU connector and C-119 (terminal 
No. 65) engine-ECU connector.

NOTE: Before checking harness, check intermediate 
connector C-124

*1

 or C-122

*2

, and repair if neces-

sary.

• Check output line for short circuit.

Q: Is the check result normal?

YES : 

Check Air conditioner (Refer to GROUP 55 

− Troubleshooting − Check Chart For 
Trouble Symptoms 

P.55-29

).

NO : 

Repair the damaged harness wire.

STEP 8. Connector check: C-37 A/C-ECU 
connector

Q: Is the check result normal?

YES : 

Check intermediate connector C-124

*1

 or 

C-122

*2

, and repair if necessary. If 

intermediate connector is normal, check and 
repair harness between C-37 (terminal No. 
32) A/C-ECU connector and C-119 (terminal 
No. 65) engine-ECU connector.

• Check output line for open circuit.

NO : 

Repair or replace the connector.

AK502007

28
36

27
35

26
34

25
33

24
32

23
31

22
30

21
29

AB

C-37 (B)

Harness side 
connector

Connector: C-37

AK501994

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

AB

Connector: C-119

C-119 (GR)

C-119 (GR)

Harness side connector

<L. H. drive vehicles>

<R. H. drive vehicles>

AK502007

28
36

27
35

26
34

25
33

24
32

23
31

22
30

21
29

AB

C-37 (B)

Harness side 
connector

Connector: C-37

AK501994

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

AB

Connector: C-119

C-119 (GR)

C-119 (GR)

Harness side connector

<L. H. drive vehicles>

<R. H. drive vehicles>

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-356

Inspection Procedure 30: Ignition Circuit System <L. H. drive vehicles>

1 2 3

1 2 3

AK501836

1 2 3
4 5 6

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

LOCK

ACC

IG1

R

IG2

ST

10 A

Engine-ECU

2

1

1

3

3

2

11

12

Ignition switch

C-208

B-W

Y-G

W

W-R

W-R

B-Y

B

B

B

B

B-G

2

10

C-214

C-129

18

4

A-29

6

C-211

J/B

Ignition circuit

Spark
plug

AB

Ignition coil 2

B-114

(MU802064)

Ignition coil 1

B-103

(MU802064)

C-121

(MU803784)

1

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-357

OPERATION

• The battery voltage is applied to the ignition coil 

(terminal No. 1) from the ignition switch and is 
earthed to the vehicle body from the ignition coil 
(terminal No. 2).

• A power voltage of 12 V is applied to the ignition 

coil output terminal (terminal No. 3) from the 
engine-ECU (terminal No. 11 and No. 12).

FUNCTION

• When the engine-ECU makes the power transis-

tor in the unit be in "OFF" position, the battery 
voltage in the unit is applied to the power transis-
tor unit, and that makes the power transistor unit 
be in "ON" position. The engine-ECU makes the 
power transistor in the unit be in "ON", and that 
makes the power transistor unit be in "OFF" posi-
tion.

• In response to the signal from the engine-ECU, 

the power transistor unit is in "ON" position. The 
primary current is going to the ignition coil. When 
the power transistor unit is in "OFF" position, the 
primary current is interrupted and high voltage is 
generated in the secondary coil.

PROBABLE CAUSES

• Failed ignition coil

• Failed spark plug

• Failed spark plug cable

• Open/short circuit in ignition primary circuit or 

loose connector contact

• Failed engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. Check spark plug cable itself.

• Check spark plug cable itself (Refer to GROUP 

16 

− Ignition System − On-vehicle Service 

P.16-29

).

Q: Is the check result normal?

YES : 

Go to Step 2 .

NO : 

Replace the spark plug cable.

STEP 2. Check spark plug.

Q: Is the check result normal?

YES : 

Go to Step 3 .

NO : 

Replace the spark plug.

STEP 3. Connector check: B-103 and B-114 
ignition coil connectors

Q: Is the check result normal? 

YES : 

Go to Step 4 .

NO : 

Repair or replace the connector.

STEP 4. Check ignition coil itself.

• Check ignition coil itself (Refer to GROUP 16 − 

Ignition System 

− On-vehicle Service 

P.16-28

).

Q: Is the check result normal? 

YES : 

Go to Step 5 .

NO : 

Replace the ignition coil.

STEP 5. Perform voltage measurement at B-103 
and B-114 ignition coil connectors.

• Disconnect connector, and measure at harness 

side.

• Ignition switch: "ON" 

• Voltage between terminal No. 1 and earth.

OK: System voltage

Q: Is the check result normal? 

YES : 

Go to Step 7 .

NO : 

Go to Step 6 .

AK305047

1

2

3

Connector : B-103, B-114

B-114(GR)

B-103(GR)

AB

Harness side 
connector

AK305047

1

2

3

Connector : B-103, B-114

B-114(GR)

B-103(GR)

AB

Harness side 
connector

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-358

STEP 6. Connector check: C-208 ignition switch 
connector

Q: Is the check result normal? 

YES : 

Check intermediate connectors A-29, 

C-129, C-211 and C-214, and repair if 
necessary. If intermediate connectors are 
normal, check and repair harness between 
C-208 (terminal No. 2) ignition switch 
connector and B-114 (terminal No. 1) 
ignition coil connector, also between C-208 
(terminal No. 2) ignition switch connector 
and B-103 (terminal No. 1) ignition coil 
connector.

• Check power supply line for 

open/short circuit.

NO : 

Repair or replace the connector.

STEP 7. Perform voltage measurement at B-103 
and B-114 ignition coil connectors.

• Disconnect connector, and measure at harness 

side.

• Engine: Cranking

• Voltage between terminal No. 3 and earth.

OK: 0.5 

− 4.0 V

Q: Is the check result normal? 

YES : 

Go to Step 13 .

NO : 

Go to Step 8 .

1

2

3

4

5

6

AK305446

Harness side 
connector

Connector: C-208

C-208

AB

AK305047

1

2

3

Connector : B-103, B-114

B-114(GR)

B-103(GR)

AB

Harness side 
connector

AK305047

1

2

3

Connector : B-103, B-114

B-114(GR)

B-103(GR)

AB

Harness side 
connector