Mitsubishi 380. Manual — part 630

MULTIPORT FUEL INJECTION (MPI) DIAGNOSIS

MULTIPORT FUEL INJECTION (MPI) <3.8L ENGINE>

13A-612

STEP 9. Measure the power supply voltage at ECU harness
side connector B-20.
(1) Disconnect the connector B-20 and measure at the harness

side.

(2) Using a jumper wire, connect terminal No. 24 to ground.

(3) Measure the voltage between terminals (No. 05) and

ground.

• Voltage should be battery positive voltage.

Q: Is battery positive voltage (approximately 12 volts)

present?
YES : Replace the ECU. Then confirm that the malfunction

symptom is eliminated.

NO : Repair harness wire between MPI relay connector

B-17X (terminal No. 4) and ECU connector B-20
(terminal No. 05) because of open circuit. Then
confirm that the malfunction symptom is eliminated.

16DB400A

COVER

ENGINE

CONTROL

UNIT

AIR

CLEANER

03DB165A

B-20 HARNESS

CONNECTOR

MULTIPORT FUEL INJECTION (MPI) DIAGNOSIS

MULTIPORT FUEL INJECTION (MPI) <3.8L ENGINE>

13A-613

INSPECTION PROCEDURE 25: Fuel pump system.

.

CIRCUIT OPERATION

• Battery positive voltage is applied to the fuel

pump relay 1 (terminal No. 3) from the ignition

switch-IG.
Ground is provided through terminal No. 2 to
chassis ground.

03DB166A

CONNECTOR: C-208, C-210

JUNCTION

BLOCK

HARNESS

CONNECTOR

C-208

C-210

3

4

1

2

3

4

1

2

03DB171A

CONNECTOR: C-29

C-29

1

2

3

4

5

03DB168A

SERVICE

HOLE

FUEL PUMP MODULE

(INCORPORATING FUEL

LEVEL SENSOR (MAIN)

CONNECTOR: D-18

D-18 (GR)

HARNESS

CONNECTOR:

COMPONENT SIDE

03DB174A

CONNECTOR: C-214

JUNCTION

BLOCK

C-214

16DB400A

COVER

ENGINE

CONTROL

UNIT

AIR

CLEANER

03DB173A

CONNECTOR: C-215

JUNCTION

BLOCK

C-215

03DB170A

CONNECTOR: C-308

C-308

03DB172A

CONNECTOR: C-211

C-211

JUNCTION

BLOCK

MULTIPORT FUEL INJECTION (MPI) DIAGNOSIS

MULTIPORT FUEL INJECTION (MPI) <3.8L ENGINE>

13A-614

• When the ignition switch is turned to the "ON"

position, the battery positive voltage is applied to
the fuel pump relay 2 (terminal No. 1) from the
fuel pump relay 1 (terminal No. 1).

• Battery positive voltage is applied to the fuel

pump relay 2 (terminal No. 3) from the ignition
switch-IG.

• During cranking and while the engine is running,

the ECU turns the power transistor in the ECU
ON to ground the fuel pump relay 2 coil. With this,
the fuel pump relay turns ON, and the battery
positive voltage is supplied to the fuel pump from
the fuel pump relay 2 (terminal No. 4).

.

TROUBLESHOOTING HINTS (The most
likely causes for this code to be set are:)

• Malfunction of the fuel pump relay.

• Malfunction of the fuel pump.

• Improper connector contact, open or short-circu-

lated harness wire.

• Malfunction of the ECU.

• Refer to component locations GROUP-

70

• Refer to configuration diagrams GROUP-

80

• Refer to circuit diagrams GROUP-

90

DIAGNOSIS

Required Special Tools:

• Diagnostic tool(MUT-III Sub Assembly)

• MB991824: V.C.I.

• MB991827: USB Cable

• MB991910: Main Harness A

STEP 1. Check fuel pump operation.
(1) Turn the ignition switch to "ON". Listen for fuel pump

running for approximately 2 seconds. Pump will
automatically stop after this time.

NOTE: As the fuel pump is an in-tank type, the fuel pump
sound is hard to hear. Remove the fuel tank filler tube cap
and check from the tank inlet.

(2) Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is the fuel pump operating properly?

YES : That this malfunction is intermittent. Refer to GROUP

00, How to Use Troubleshooting/Inspection Service
Points

− How to Cope with Intermittent Malfunctions

P.00-14

.

NO : Go to Step 2.

STEP 2. Check harness connector C-210 at fuel pump relay
1 and harness connector C-208 at fuel pump relay 2 for
damage.
Q: Is the harness connector in good condition?

YES : Go to Step 3.
NO : Repair or replace it. Refer to GROUP 00E, Harness

Connector Inspection

P.00E-2

. Then confirm that the

malfunction symptom is eliminated.

03DB166A

CONNECTOR: C-208, C-210

JUNCTION

BLOCK

HARNESS

CONNECTOR

C-208

C-210

3

4

1

2

3

4

1

2

MULTIPORT FUEL INJECTION (MPI) DIAGNOSIS

MULTIPORT FUEL INJECTION (MPI) <3.8L ENGINE>

13A-615

STEP 3. Check the fuel pump relay 1 and 2.

CAUTION

Because it is not possible to distinguish the top and the
bottom of the fuel pump relay, inspect it with the triangle
mark printed on the relay facing upward.
(1) Remove the fuel pump relay 1 and 2.

(2) Check for continuity between the each fuel pump relay

terminals No. 2 and No. 3.

• There should be continuity. (approximately 70 ohms)

(3) Use jumper wires to connect each fuel pump relay terminal

No. 3 to the positive battery terminal and terminal No. 2 to
the negative battery terminal.

(4) Check for continuity between the each fuel pump relay

terminals No. 1 and No. 4 while connecting and
disconnecting the jumper wire at the negative battery
terminal.

• Should be less than 2 ohms. (Negative battery terminal

connected)

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

nected)

(5) Install the fuel pump relay 1 and 2.

Q: Is the measured resistance normal?

YES : Go to Step 4.
NO : Replace the fuel pump relay 1 and/or 2. Then confirm

that the malfunction symptom is eliminated.

03DB166A

CONNECTOR: C-208, C-210

JUNCTION

BLOCK

HARNESS

CONNECTOR

C-208

C-210

3

4

1

2

3

4

1

2

AK104052

2

3 4

1

FUEL PUMP

RELAY SIDE

CONNECTOR

AB

AK104053

1 2

3 4

AB

FUEL PUMP

RELAY SIDE

CONNECTOR