Mitsubishi Lancer Evolution IX. Manual - part 462

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-323

STEP 23. Check harness between B-120 (terminal 
No. 2 and No. 4) fuel pump relay (3) connector 
and B-121 (terminal No. 1) fuel pump resistor 
connector.
NOTE: Before checking harness, check intermediate 
connector C-123, and repair if necessary.

• Check power supply line for damage.

Q: Is the check result normal? 

YES : 

Replace the engine-ECU.

NO : 

Repair the damaged harness wire.

AK305262

2 1

3

4

Harness side connector

Connector: B-120

B-120

B-120

AB

<L. H. drive vehicles>

<R. H. drive vehicles>

Junction block’s
triangle marks

AK305259

1

2

Harness side connector

Connector: B-121

B-121(B)

B-121(B)

AB

<L. H. drive vehicles>

<R. H. drive vehicles>

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-324

Inspection Procedure 25: Radiator Fan Control Relay System

1

2

3

4

1

3

2

4

AK501830

1 2 3

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

20A

Battery

W

W

Radiator fan control relay circuit

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

Engine control relay

Relay relay

To engine-ECU

Engine-ECU

J/C (6)
C-105

B-Y

B-Y

R-Y

B-12X

28

1

2

3

4

Radiator
fan control relay

R-Y

R-Y

1

3

B

33

A-13 (*1)
3  

A-13
2  (*1) or 1  (*2)

B-W

L-B

A-09X

Fusible link (2)

4

3

2

31

L

2

Fan control
circuit

Fan
controller

A-17

(MU802322)

C-121

(MU803784)

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

AB

Engine control system

B-Y

8

C-31 (*2)
12 

L

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-325

OPERATION

• The battery voltage is applied to the fan control 

relay (terminal No. 1) form the engine control 
relay (terminal No. 4) and is earthed to the vehi-
cle body from the radiator fan control relay (termi-
nal No. 3).

• The battery voltage is applied to the radiator fan 

control relay (terminal No. 4).

• When the radiator fan control relay is in "ON" 

position, the battery voltage is supplied to the fan 
controller (terminal No.3) from the radiator fan 
control relay (terminal No. 2).

FUNCTION

• When the engine control relay turns "ON", the 

radiator fan control relay turns "ON" simultane-
ously, and power is supplied to the fan controller. 
The radiator fan motor is driven when the fan 
motor drive signal is input to the fan controller 
from the engine-ECU.

PROBABLE CAUSES

• Failed radiator fan control relay

• Failed fan controller

• Failed radiator fan motor

• Failed engine-ECU

DIAGNOSIS PROCEDURE

NOTE: 

.

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

STEP 1. Connector check: A-09X radiator fan 
control relay connector.

Q: Is the check result normal? 

YES : 

Go to Step 2 .

NO : 

Repair or replace the connector.

STEP 2. Check radiator fan control relay.

• Check radiator fan control relay (Refer to 

GROUP 14 

− On-vehicle Service 

P.14-17

).

Q: Is the check result normal? 

YES : 

Go to Step 3 .

NO : 

Replace the fan control relay.

STEP 3. Perform resistance measurement at 
A-09X radiator fan control relay connector.

• Remove relay, and measure at relay box side.

• Resistance between terminal No.3 and earth.

OK: 2

Ω or less

Q: Is the check result normal?

YES : 

Go to Step 4 .

NO : 

Check and repair harness between A-09X 

(terminal No. 3) radiator fan control relay 
connector and body earth.

• Check and earthing line for open 

circuit and damage.

STEP 4. Perform voltage measurement at A-09X 
radiator fan control relay connector.

• Remove relay, and measure at relay box 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 .

AK305263

3

1

2

4

AB

A-09X

Harness side
connector

Connector: A-09X

AK305263

3

1

2

4

AB

A-09X

Harness side
connector

Connector: A-09X

AK305263

3

1

2

4

AB

A-09X

Harness side
connector

Connector: A-09X

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-326

STEP 5. Connector check: B-12X engine control 
relay connector.

Q: Is the check result normal? 

YES : 

Check intermediate connectors A-13*

1

 or 

C-31*

2

 and C-105, and repair if necessary. If 

intermediate connectors are normal, check 
and repair harness between B-12X (terminal 
No. 4) engine control relay connector and 
A-09X (terminal No. 1) radiator fan control 
relay connector.

• Check power supply line for 

open/short circuit.

NO : 

Repair or replace the connector.

STEP 6. Perform voltage measurement at A-09X 
radiator fan control relay connector.

• Remove relay, and measure at relay box side.

• Voltage between terminal No. 4 and earth.

OK: System voltage

Q: Is the check result normal? 

YES : 

Go to Step 7 .

NO : 

Check and repair harness between battery 

and A-09X (terminal No. 4) radiator fan 
control relay connector.

• Check power supply line for 

open/short circuit.

STEP 7. Connector check: A-17 fan controller 
connector

Q: Is the check result normal? 

YES : 

Go to Step 8 .

NO : 

Repair or replace the connector.

AK305003

2

1

3

4

AB

Connector : B-12X

B-12X

Harness side 
connector

Relay box’s
triangle marks

AK305263

3

1

2

4

AB

A-09X

Harness side
connector

Connector: A-09X

AK305263

3

1

2

4

AB

A-09X

Harness side
connector

Connector: A-09X

AK305256

1

2

3

AB

Connector: A-17

A-17 (GR)

Harness side connector