Mitsubishi Grandis. Manual - part 767

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-319

DIAGNOSIS PROCEDURE

STEP 1. Connector check: C-110 engine-ECU 
<M/T> connector or engine-ECU <A/T> or 
engine-ECU

Q: Is the check result normal?

YES : 

Go to Step 2 .

NO : 

Repair or replace.

STEP 2. Check at C-110 engine-ECU <M/T> 
connector or engine-A/T-ECU <A/T> connector.

• Disconnect connector, and measure at harness 

side.

• Ignition switch: ON

• Short-circuit terminal No. 17 to earth.

OK: Fan motor stops rotating.

Q: Is the check result normal?

YES : 

Go to Step 3 .

NO : 

Go to Step 4 .

STEP 3. Check the trouble symptoms.

Q: Does trouble symptom persist?

YES : 

Replace engine-ECU <M/T> or 

engine-A/T-ECU <A/T>.

NO : 

Intermittent malfunction (Refer to GROUP 
00 

− How to Use 

Troubleshooting/Inspection Service Points 

P.00-5

).

AK305618AB

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Connector: C-110

<L.H. drive vehicles>

<R.H. drive vehicles>

C-110 (GR)

C-110 (GR)

Harness side connector

AK305618AB

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Connector: C-110

<L.H. drive vehicles>

<R.H. drive vehicles>

C-110 (GR)

C-110 (GR)

Harness side connector

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-320

STEP 4. Perform voltage measurement at C-110 
engine-ECU <M/T> connector.

• Disconnect connector, and measure at harness 

side.

• Ignition switch: ON

• Voltage between terminal No. 17 and earth.

OK: 4.9 

− 5.1 V

Q: Is the check result normal?

YES : 

Replace fan controller.

NO : 

Go to Step 5 .

STEP 5. Connector check: A-26 fan controller 
connector

Q: Is the check result normal?

YES : 

Go to Step 6 .

NO : 

Repair or replace.

STEP 6. Check harness between A-26 (terminal 
No. 2) fan controller connector and C-110 
(terminal No. 17) engine-ECU <M/T> connector.

NOTE: Before checking harness, check intermediate 
connector A-16, and repair if necessary.

• Check output line for open circuit.

Q: Is the check result normal?

YES : 

Replace fan controller.

NO : 

Repair.

AK305618AB

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Connector: C-110

<L.H. drive vehicles>

<R.H. drive vehicles>

C-110 (GR)

C-110 (GR)

Harness side connector

AK300999

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3

AC

Harness side connector

Connector: A-26

 A-26 (GR)

AK300999

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3

AC

Harness side connector

Connector: A-26

 A-26 (GR)

AK305618AB

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Connector: C-110

<L.H. drive vehicles>

<R.H. drive vehicles>

C-110 (GR)

C-110 (GR)

Harness side connector

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-321

Inspection Procedure 22: Engine-ECU <M/T> or Engine-A/T-ECU <A/T> Power Supply, Engine Control 
Relay, Ignition Switch-IG1 System

AK305578

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41 42 43

50 51

5253

545556

57 58

33 34

31

353637383940
444546474849

32

1 2 3

4 5 6

1 2

3 4

5 6 7

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8

B-15X

C-111

(MU803803)

C-115

(MU801850)

IG2

ST

R

LOCK

ACC

IG1

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20A

8

7.5A

Fusible link (26)

Ignition switch

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28

J/B

50

C-18

C-205

C-202

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58

Engine 
control 
relay

4

3

1

11

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2

57

Battery
backup

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34

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33

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B

B

B

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11

J/C (4)
C-116

Power
source

2

1

A-16

3

A-16

Relay box

W

W

W-G

W-G

W-G

W-G

W-G

L-B

L-B

L-B

Y-G

R-W

R-W

R-W

Power supply and ignition switch-IG circuit

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

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

C-307

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-322

OPERATION

• The battery voltage is applied to the engine 

control relay (terminal No. 3 and 4).

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

<A/T> (terminal No. 57) makes the power 
transistor in the unit be in "ON" position and 
makes currents go on the engine control relay 
coil, and that makes the relay be in "ON" position.

• When the engine control relay is in "ON" position, 

the battery voltage is supplied to the engine-ECU 
<M/T> or engine-A/T-ECU <A/T> (terminal No. 
34 and No. 43), the sensor and the actuator from 
the engine control relay (terminal No. 1).

FUNCTION

• When the ignition switch ON signal is input to the 

engine-ECU <M/T> or engine-A/T-ECU <A/T>, 
the engine-ECU <M/T> or engine-A/T-ECU 
<A/T> places the engine control relay in the ON 
position. Accordingly, the battery voltage is 
supplied to the engine-ECU <M/T> or 
engine-A/T-ECU <A/T>, sensor and actuator.

PROBABLE CAUSE

• Failed engine control relay

• Open/short circuit in engine control relay circuit or 

loose connector contact

• Failed engine-ECU <M/T>

• Failed engine-A/T-ECU <A/T>

DIAGNOSIS PROCEDURE

STEP 1. Check battery voltage.

• Measure battery voltage during cranking.

OK: 8 V or more

Q: Is the check result normal?

YES : 

Go to Step 2 .

NO : 

Check battery (Refer to GROUP 54A 

− 

Battery 

− On-vehicle Service − Battery test 

P.54A-6

).

STEP 2. Connector check: B-15X engine control 
relay connector

Q: Is the check result normal?

YES : 

Go to Step 3 .

NO : 

Repair or replace.

STEP 3. Check engine control relay.

• Check engine control relay (Refer to 

P.13A-388

).

Q: Is the check result normal?

YES : 

Go to Step 4 .

NO : 

Replace engine control relay.

STEP 4. Perform voltage measurement at B-15X 
engine control relay connector.

• Remove relay, and measure at relay box side.

• Voltage between terminal No. 3 and earth, also 

between terminal No. 4 and earth.

OK: System voltage

Q: Is the check result normal?

YES : 

Go to Step 5 .

NO : 

Check intermediate connector A-16, and 

repair if necessary. If intermediate 
connector is normal, check and repair 
harness between B-15X (terminal No. 3 and 
terminal No. 4) engine control relay 
connector and battery.

• Check power supply line for 

open/short circuit.

AK300967

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1

3

4

AC

Harness side
connector

B-15X

Connector: B-15X

Relay box’s
triangle marks

AK300967

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1

3

4

AC

Harness side
connector

B-15X

Connector: B-15X

Relay box’s
triangle marks