Mitsubishi Grandis. Manual — part 776

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-355

Inspection Procedure 26: Ignition Circuit System

AK305582

31

35363738394041 42 43
444546474849

50 51

5253

545556

57 58

32

33 34

1 2 3

1 2 3

1 2 3

1 2 3

1 2 3

4 5 6

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

LOCK

ACC

IG1 IG2

ST

10A

Ignition coil 1

Engine-ECU <M/T> or
engine-A/T-ECU <A/T>

B-02

(MU802064)

B-03

(MU802064)

B-04

(MU802064)

B-05

(MU802064)

Ignition coil 2

Ignition coil 3

Ignition coil 4

2

3

31

32

35

52

Capacitor

B-113

Ignition switch

L-B

W

W

W

W

W

W

B-L

W-L

B-P

Y

B

B

B

B

2

6

10

C-205

C-18

1

C-202

J/B

Ignition circuit

C-111

(MU803803)

AB

Spark
plug

2

1

1

1

1

1

3

Spark
plug

2

3

Spark
plug

2

3

Spark
plug

C-307

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-356

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 <M/T> or engine-A/T-ECU <A/T>
(terminals No. 31, No. 32, No. 35 and No. 52).

FUNCTION

• When the engine-ECU <M/T> or engine-A/T-ECU

<A/T> makes the power transistor in the unit be
in OFF position, the battery voltage in the unit is
applied to the power transistor unit, and that
makes the power transistor unit be in ON
position. The engine-ECU <M/T> or
engine-A/T-ECU <A/T> makes the power
transistor in the unit be in ON, and that makes the
power transistor unit be in OFF position.

• In response to the signal from the engine-ECU

<M/T> or engine-A/T-ECU <A/T>, 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 CAUSE

• Failed ignition coil

• Failed spark plug

• Failed spark plug cable

• Open/short circuit in ignition primary circuit or

loose connector contact

• Failed engine-ECU <M/T>

• Failed engine-A/T-ECU <A/T>

DIAGNOSIS PROCEDURE

STEP 1. Check spark plug.

Q: Is the check result normal?

YES :

Go to Step 2 .

NO :

Replace spark plug.

STEP 2. Connector check: B-02, B-03, B-04 and
B-05 ignition coil connectors

Q: Is the check result normal?

YES :

Go to Step 3 .

NO :

Repair or replace.

STEP 3. Check ignition coil itself.

• Check ignition coil itself (Refer to GROUP 16 −

Ignition System

− On-vehicle Service − Ignition

coil check

P.16-26

).

Q: Is the check result normal?

YES :

Go to Step 4 .

NO :

Replace ignition coil.

STEP 4. Perform voltage measurement at B-02,
B-03, B-04 and B-05 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 6 .

NO :

Go to Step 5 .

AK300980

1

2

3

AC

B-02 (GR) B-03 (GR) B-04 (GR) B-05 (GR)

Connectors: B-02, B-03, B-04, B-05

Harness side connector

AK300980

1

2

3

AC

B-02 (GR) B-03 (GR) B-04 (GR) B-05 (GR)

Connectors: B-02, B-03, B-04, B-05

Harness side connector

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-357

STEP 5. Connector check: C-307 ignition switch
connector

Q: Is the check result normal?

YES :

Check intermediate connectors C-18, C-202

and C-205, and repair if necessary. If
intermediate connectors are normal, check
and repair harness between ignition switch
connector and ignition coil connector

a. Check and repair harness between

C-307 (terminal No. 2) ignition switch
connector and B-02 (terminal No. 1)
No. 1 ignition coil connector

b. Check and repair harness between

C-307 (terminal No. 2) ignition switch
connector and B-03 (terminal No. 1)
No. 2 ignition coil connector

c. Check and repair harness between

C-307 (terminal No. 2) ignition switch
connector and B-04 (terminal No. 1)
No. 3 ignition coil connector

d. Check and repair harness between

C-307 (terminal No. 2) ignition switch
connector and B-05 (terminal No. 1)
No. 4 ignition coil connector

• Check power supply line for

open/short circuit.

NO :

Repair or replace.

STEP 6. Perform voltage measurement at B-02,
B-03, B-04 and B-05 ignition coil connectors.

• Disconnect connector, and measure at harness

side.

• Engine: Cranking

• Voltage between terminal No. 3 and earth.

OK: 0.3

− 3.0 V

Q: Is the check result normal?

YES :

Go to Step 12 .

NO :

Go to Step 7 .

1

2

3

4

5

6

AK305629

C-307

C-307

Connector: C-307

Harness side connector

<R.H.drive vehicle>

<L.H.drive vehicle>

AB

AK300980

1

2

3

AC

B-02 (GR) B-03 (GR) B-04 (GR) B-05 (GR)

Connectors: B-02, B-03, B-04, B-05

Harness side connector

AK300980

1

2

3

AC

B-02 (GR) B-03 (GR) B-04 (GR) B-05 (GR)

Connectors: B-02, B-03, B-04, B-05

Harness side connector

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-358

STEP 7. Perform voltage measurement at C-111
engine-ECU <M/T> connector or engine-A/T-ECU
<A/T>.

• Measure engine-ECU <M/T> or engine-A/T-ECU

<A/T> terminal voltage.

• Disconnect B-02, B-03, B-04 and B-05 ignition

coil connectors.

• Engine: Cranking

a. Voltage between terminal No. 31 and earth

(No. 1 Ignition coil).

b. Voltage between terminal No. 32 and earth

(No. 2 Ignition coil).

c. Voltage between terminal No. 35 and earth

(No. 3 Ignition coil).

d. Voltage between terminal No. 52 and earth

(No. 4 Ignition coil).

OK: 0.3

− 3.0 V

Q: Are the check results normal?

YES :

Go to Step 8 .

NO :

Go to Step 9 .

STEP 8. Connector check: C-111 engine-ECU
<M/T> connector or engine-A/T-ECU <A/T>
connector

Q: Is the check result normal?

AK305625AB

Connector: C-111

<L.H. drive vehicles>

<R.H. drive vehicles>

C-111 (GR)

C-111 (GR)

Harness side connector

31

32

33

34

35

36

37

38

39

40

41

42

43

44

45

46

47

48

49

52

53

54

55

56

57

58

50

51

AK300980

1

2

3

AC

B-02 (GR) B-03 (GR) B-04 (GR) B-05 (GR)

Connectors: B-02, B-03, B-04, B-05

Harness side connector

AK305625AB

Connector: C-111

<L.H. drive vehicles>

<R.H. drive vehicles>

C-111 (GR)

C-111 (GR)

Harness side connector

31

32

33

34

35

36

37

38

39

40

41

42

43

44

45

46

47

48

49

52

53

54

55

56

57

58

50

51

AK300980

1

2

3

AC

B-02 (GR) B-03 (GR) B-04 (GR) B-05 (GR)

Connectors: B-02, B-03, B-04, B-05

Harness side connector