Mitsubishi Lancer Evolution X. Manual - part 427

 

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Mitsubishi Lancer Evolution X. Manual - part 427

 

 

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-773

• When the fuel pump relay 2 is turned ON, the fuel 

pump drive power is supplied from the fuel pump 
relay 2 (C-314 ETACS-ECU connector terminal 
No. 1) to the fuel pump (terminal No. 5).

• When the vehicle is driven at low engine loads, 

the ECM (terminal No. 51) turns OFF the power 
transistor of the unit. The current is not going 
through the fuel pump relay 1, and then the relay 
is turned OFF.

• When the vehicle is driven at high engine loads, 

the ECM (terminal No. 51) turns ON the power 
transistor of the unit. The current is going through 
the fuel pump relay 1 (terminal No. 1), and then 
the relay is turned ON. Thus the fuel pump drive 
power is supplied from the fuel pump relay 1 (ter-
minal No. 3) to the fuel pump relay 2 (C-307 
ETACS-ECU connector terminal No. 1).

.

COMMENT

• The ECM turns ON the fuel pump relay 2 during 

the engine cranking and running, and then sup-
plies the drive power to the fuel pump.

• The ECM supplies the drive power to the fuel 

pump via the resistor during the engine running at 
low engine loads. The ECM supplies the drive 
power directly to the fuel pump during the engine 
running at high engine loads to increase the fuel 
discharge rate of fuel pump. 

.

TROUBLESHOOTING HINTS (The most 
likely causes for this case:)

• Malfunction of the fuel pump relay 1.
• Malfunction of fuel pump relay 2 of ETACS-ECU.
• Malfunction of the fuel pump.
• Malfunction of the fuel pump circuit resistor.
• Improper connector contact, open or short-circu-

lated harness wire.

• Malfunction of the ECM.

DIAGNOSIS

Required Special Tools:

• MB991958: Scan Tool (M.U.T.-III Sub Assembly)

• MB991824: V.C.I.
• MB991827: USB Cable
• MB991910: Main Harness A

STEP 1. Check harness connector C-304, C-307, C314 and 
C-317 at ETACS-ECU for damage.
Q: Is the connector in good condition?

YES : Go to Step 2.
NO :  Repair or replace it. Refer to GROUP 00E, Harness 

Connector Inspection 

P.00E-2

. Then confirm that the 

malfunction symptom is eliminated.

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-774

STEP 2. Check the fuel pump relay 2.
(1) Remove the ETACS-ECU.
(2) Use jumper wires to connect C-317 ETACS-ECU terminal 

No. 6 to the positive battery terminal and C-304 
ETACS-ECU terminal No. 11 to the negative battery 
terminal.

(3) Check for continuity between the C-307 ETACS-ECU 

terminal No. 1 and C-314 ETACS-ECU terminal No. 1 while 
connecting and disconnecting the jumper wire at the 
negative battery terminal.

• Continuity (2 Ω or less) <Negative battery terminal con-

nected>

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

nected>

(4) Install the ETACS-ECU.
Q: Is the measured resistance normal?

YES : Go to Step 3.
NO :  Replace the ETACS-ECU. Then confirm that the 

malfunction symptom is eliminated.

STEP 3. Check harness connector A-27X at fuel pump 
relay 1 for damage.
Q: Is the connector in good condition?

YES : Go to Step 4.
NO :  Repair or replace it. Refer to GROUP 00E, Harness 

Connector Inspection 

P.00E-2

. Then confirm that the 

malfunction symptom is eliminated.

1 2 3 4

5 6 7

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131415

12

1 2

1 2

1

6

4

5

9

8

10 11

13

15

14

12

16

7

2 3

AK703917AC

C-314
ETACS-ECU
side connector

C-307
ETACS-ECU
side connector

C-304
ETACS-ECU
side connector

C-317 ETACS-ECU
side connector

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI)

13A-775

STEP 4. Check the fuel pump relay 1.
(1) Remove the fuel pump relay 1.
(2) Check for continuity between the throttle actuator control 

motor relay terminal No. 1 and No. 2.

• There should be continuity.

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

2 to the positive battery terminal and terminal No. 1 to the 
negative battery terminal.

(4) Check the continuity between the  fuel pump relay 1 

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

• Continuity (2 Ω or less) <Negative battery terminal con-

nected.>

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

nected.>

(5) Install the throttle actuator control motor relay.
Q: Is the measured resistance normal?

YES : Go to Step 5.
NO :  Replace the fuel pump relay 1. Then confirm that the 

malfunction symptom eliminated.

STEP 5. Check harness connector A-58 fuel pump circuit 
resistor.
Q: Is the 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 confirm that the 

malfunction symptom is eliminated.

STEP 6. Check the fuel pump circuit resistor.
(1) Disconnect the fuel pump circuit resistor connector.
(2) Measure the resistance between terminals.

Standard value: 0.45 − 0.65 Ω [at 20° C (68° F)]

Q: Is the measured resistance normal?

YES : Go to Step 7.
NO :  Replace the fuel pump circuit resistor. Then confirm 

that the malfunction symptom eliminated.

AK604234

1

2

3
4

Fuel pump relay 1
side connector

AC

AK604235

1

2

3
4

AD

Fuel pump relay 1
side connector

1 2

AK202413 AC

Fuel pump circuit
resistor side connector

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI)

13A-776

STEP 7. Check harness connector B-10 at ECM for 
damage.
Q: Is the connector in good condition?

YES : Go to Step 8.
NO :  Repair or replace it. Refer to GROUP 00E, Harness 

Connector Inspection 

P.00E-2

. Then confirm that the 

malfunction symptom is eliminated.

STEP 8. Measure the power supply voltage at ECM 
connector B-10.
(1) Disconnect the connector B-10 and measure at the harness 

side.

(2) Turn the ignition switch to the "ON" position.
(3) Measure the voltage between terminal No. 96 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 9.
NO :  Repair harness wire between ETACS-ECU connector 

C-304 (terminal No. 11) and ECM connector B-10 
(terminal No. 96) because of open circuit. Then 
confirm that the malfunction symptom is eliminated.

STEP 9. Check harness connector B-09 at ECM for 
damage.
Q: Is the connector in good condition?

YES : Go to Step 10.
NO :  Repair or replace it. Refer to GROUP 00E, Harness 

Connector Inspection 

P.00E-2

. Then confirm that the 

malfunction symptom is eliminated.

AK604054

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AC

B-10 harness
connector:
component side

 

 

 

 

 

 

 

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