Mitsubishi Lancer Evolution X. Manual - part 312

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI)

13A-313

STEP 4. Measure the power supply voltage at No. 2 
cylinder injector connector.
(1) Disconnect connector B-102 and measure at the harness 

side.

(2) Turn the ignition switch to the "ON" position.
(3) Measure the voltage between terminal No. 1 and ground.

• Voltage should be battery positive voltage.

(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is battery positive voltage (approximately 12 volts) 

present?
YES : Go to Step 14.
NO :  Go to Step 5.

STEP 5. Check harness connector A-25X at injector relay 
for damage.
Q: Is the harness connector in good condition?

YES : Go to Step 6.
NO :  Repair or replace it. Refer to GROUP 00E, Harness 

Connector Inspection 

P.00E-2

. Then go to Step 20.

STEP 6. Check the injector relay.
(1) Remove the injector relay.
(2) Check for continuity between the injector relay terminal No. 

1 and No. 2.
There should be continuity.

(3) Use jumper wires to connect injector relay terminal No. 1 to 

the positive battery terminal and terminal No. 2 to the 
negative battery terminal.

(4) Check for continuity between the injector relay terminal No. 

3 and No. 4 while connecting and disconnecting the jumper 
wire at the negative battery terminal.

• Continuity (2 ohms or less). <Negative battery terminal 

connected>

• Should be open loop. <Negative battery terminal discon-

nected>

(5) Install the injector relay.
Q: Is the measured resistance normal?

YES : Go to Step 7.
NO :  Replace the injector relay. Then go to Step 20.

AK604192

M

1

2

AB

B-102 harness
connector:
component side 

AK604033

1

2

3
4

Injector relay side connector

AB

AK604034

1

2

3
4

AB

Injector relay side connector

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI)

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STEP 7. Check for continuity at injector relay harness side 
connector A-25X.
(1) Disconnect the connector A-25X and measure at the 

harness side.

(2) Check for the continuity between terminal No. 2 and 

ground.

• Continuity (2 ohms or less).

Q: Does continuity exist?

YES : Go to Step 8.
NO :  Repair harness wire between injector relay connector 

A-25X (terminal No. 2) and ground because of open 
circuit or harness damage. Then go to Step 20.

STEP 8. Measure the power supply voltage at injector relay 
harness side connector A-25X.
(1) Disconnect the connector A-25X and measure at the 

harness side.

(2) Turn the ignition switch to the "ON" position.
(3) Measure the voltage between terminal No. 1 and ground.

• Voltage should be battery positive voltage.

Q: Is battery positive voltage (approximately 12 volts) 

present?
YES : Go to Step 10.
NO :  Go to Step 9.

STEP 9. Check harness connector C-304 at ETACS-ECU for 
damage.
Q: Is the harness connector in good condition?

YES : Check harness connector C-50 at intermediate 

connector for damage, and repair or replace as 
required. Refer to GROUP 00E, Harness Connector 
Inspection 

P.00E-2

. If intermediate connector is in 

good condition, repair harness wire between injector 
relay connector A-25X (terminal No. 1) and 
ETACS-ECU connector C-304 (terminal No. 10) 
because of open circuit or short circuit to ground. 
Then go to Step 20.

NO :  Repair or replace it. Refer to GROUP 00E, Harness 

Connector Inspection 

P.00E-2

. Then go to Step 20.

AK604037

2

1

3
4

AD

A-25X harness
connector:
component side

AK604036

2

1

3
4

AD

A-25X harness
connector:
component side

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI)

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STEP 10. Measure the power supply voltage at injector 
relay harness side connector A-25X.
(1) Disconnect the connector A-25X and measure at the 

harness side.

(2) Turn the ignition switch to the "ON" position.
(3) Measure the voltage between terminal No. 4 and ground.

• Voltage should be battery positive voltage.

Q: Is battery positive voltage (approximately 12 volts) 

present?
YES : Go to Step 12.
NO :  Go to Step 11.

STEP 11. Check harness connector A-34X at MFI relay for 
damage.
Q: Is the harness connector in good condition?

YES : Repair harness wire between MFI relay connector 

A-34X (terminal No. 2) and injector relay 
connector A-25X (terminal No. 4) because of open 
circuit or short circuit to ground. Then go to Step 
20.

NO :  Repair or replace it. Refer to GROUP 00E, Harness 

Connector Inspection 

P.00E-2

. Then go to Step 20.

STEP 12. Check for open circuit or short circuit to ground 
between injector relay connector A-25X (terminal No. 3) 
and No. 2 cylinder injector connector B-102 (terminal No. 
1).
NOTE: Check harness after checking intermediate connector 
A-39. If intermediate connector is damaged, repair or replace it. 
Refer to GROUP 00E, Harness Connector Inspection 

P.00E-2

. 

Then go to Step 20 .
Q: Is the harness wire in good condition?

YES : Go to Step 13.
NO :  Repair it. Then go to Step 20.

2

1

3
4

AK604035 AD

A-25X harness
connector:
component side

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI)

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STEP 13. Check harness connector C-304 at ETACS-ECU 
for damage.
Q: Is the harness connector in good condition?

YES : Check harness connector C-50 at intermediate 

connector for damage, and repair or replace as 
required. Refer to GROUP 00E, Harness Connector 
Inspection 

P.00E-2

. If intermediate connector is in 

good condition, repair harness wire between injector 
relay connector A-25X (terminal No. 1) and 
ETACS-ECU connector C-304 (terminal No. 10) 
because of harness damage. Then go to Step 20.

NO :  Repair or replace it. Refer to GROUP 00E, Harness 

Connector Inspection 

P.00E-2

. Then go to Step 20.

STEP 14. Check harness connector A-34X at MFI relay for 
damage.
Q: Is the harness connector in good condition?

YES : Go to Step 15.
NO :  Repair or replace it. Refer to GROUP 00E, Harness 

Connector Inspection 

P.00E-2

. Then go to Step 20.

STEP 15. Check for harness damage between MFI relay 
connector A-34X (terminal No. 2) and injector relay 
connector A-25X (terminal No. 4).
Q: Is the harness wire in good condition?

YES : Go to Step 16.
NO :  Repair it. Then go to Step 20.

STEP 16. Check for harness damage between injector 
relay connector A-25X (terminal No. 3) and No. 2 cylinder 
injector connector B-102 (terminal No. 1).
NOTE: Check harness after checking intermediate connector 
A-39. If intermediate connector is damaged, repair or replace it. 
Refer to GROUP 00E, Harness Connector Inspection 

P.00E-2

. 

Then go to Step 20 .
Q: Is the harness wire in good condition?

YES : Go to Step 17.
NO :  Repair it. Then go to Step 20.

STEP 17. Check harness connector B-09 at ECM for 
damage.
Q: Is the harness connector in good condition?

YES : Go to Step 18.
NO :  Repair or replace it. Refer to GROUP 00E, Harness 

Connector Inspection 

P.00E-2

. Then go to Step 20.