Mitsubishi Lancer Evolution IX. Manual - part 410

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-115

STEP 10. Connector check: C-121 engine-ECU 
connector

Q: Is the check result normal? 

YES : 

Go to Step 11 .

NO : 

Repair or replace the connector.

STEP 11. Check harness between B-20 (terminal 
No. 2) No. 2 injector connector and C-121 
(terminal No. 9) engine-ECU connector.

• Check output line for open/short circuit or dam-

age.

Q: Is the check result normal? 

YES : 

Go to Step 12 .

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>

AK305012

1

2

Connector : B-20

Harness side connector

B-20(B)

AD

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-116

STEP 12. Perform signal wave pattern 
measurement at C-121 engine-ECU connector 
(Using an oscilloscope).

• Engine: Idling

• Transmission: Neutral

• Voltage between terminal No. 9 and earth.

OK: Waveform should be display on Inspec-
tion procedure using an oscilloscope (Refer 
to 

P.13A-385

).

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.

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-117

Code No. P0203: No. 3 Injector System

AK501809

1

2

1

2

1

2

1

2

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

1

2

3

4

B-12X

Injector
No.1

Injector
No.2

Injector
No.3

Injector resistor

Injector
No.4

B-22

MU802722

B-20

(MU802722)

B-18

(MU802722)

B-17

(MU802722)

B-119

MU802607

4

28

29

3

1

1

4

5

6

1

1

1

2

2

2

2

3

1

2

1

9

24

2

C-121

(MU803784)

Injector circuit

Battery

Engine-ECU

B-Y

B-Y

R-Y

To engine-ECU

R-Y

R

R-W

R-L

R-B

O

W-R

G

R

B-Y

Engine control relay

J/C (6)
C-105

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

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

NOTE

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

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-118

OPERATION

• Power is supplied to the injector (terminal No. 1) 

from the engine control relay (terminal No. 4) via 
the injector resistor.

• The engine-ECU (terminal No. 24) makes the 

power transistor in the unit be in "ON" position, 
and that makes currents go on the injector (termi-
nal No. 2).

FUNCTION

• The engine-ECU controls the power supply inter-

val of the injector.

• The fuel injection amount of the injector depends 

on the power supply interval.

TROUBLE JUDGMENT

Check Conditions

• The engine speed is 50 − 1,000 r/min.

• The throttle position sensor output voltage is 1.15 

V or less.

• Injector not in forced drive (actuator test) mode.

Judgment Criterion

• No surge voltage of the injector detected for 2 

seconds.

PROBABLE CAUSES

• Failed No. 3 injector

• Open/short circuit in No. 3 injector circuit or loose 

connector contact

• Failed engine-ECU 

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-II/III actuator test

• Item No. 03: No. 3 injector

OK: Idling state varies.

Q: Is the check result normal? 

YES : 

Intermittent malfunction (Refer to GROUP 

00 

− How to Use 

Troubleshooting/Inspection Service Points 

P.00-5

).

NO : 

Go to Step 2 .

STEP 2. Connector check: B-18 No. 3 injector 
connector

Q: Is the check result normal? 

YES : 

Go to Step 3 .

NO : 

Repair or replace the connector.

STEP 3. Perform resistance measurement at B-18 
No. 3 injector connector.

• Disconnect connector, and measure at injector 

side.

• Resistance between terminal No. 1 and No. 2.

OK: 2 

− 3 Ω

Q: Is the check result normal? 

YES : 

Go to Step 4 .

NO : 

Replace the No. 3 injector.

AK305012

1

2

Connector : B-18

Harness side connector

B-18(B)

AE

AK305012

1

2

Connector : B-18

Harness side connector

B-18(B)

AE