Mitsubishi 380. Manual - part 550

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

MULTIPORT FUEL INJECTION (MFI)

13A-292

STEP 8. Check for harness damage between MFI relay 
connector B-17X (terminal No. 4) and intermediate 
connector B-32 (terminal No. 9).
Q: Is the harness wire in good condition?

YES : Go to Step 9.
NO :  Repair it. Then go to Step 12.

1

2

3

4

AK303017

CONNECTOR: B-17X

FRONT OF VEHICLE

B-17X

AB

HARNESS

CONNECTOR:

COMPONENT SIDE

RELAY BOX

AK303053

3

4

5

8

9

1

2

6

7

10

CONNECTOR: B-32

HARNESS CONNECTOR:

COMPONENT SIDE

AB

B-32 (B)

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

MULTIPORT FUEL INJECTION (MFI)

13A-293

STEP 9. Check harness connector B-20 at ECU for 
damage.
Q: Is the harness 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 go to Step 12.

STEP 10. Check for open circuit and short circuit to 
ground and harness damage between intermediate 
connector B-32 (terminal No. 10) and ECU connector B-20 
(terminal No. 34).
Q: Is the harness wire in good condition?

YES : Go to Step 11.
NO :  Repair it. Then go to Step 12.

16DB400A

COVER

ENGINE

CONTROL

UNIT

AIR

CLEANER

AK303053

3

4

5

8

9

1

2

6

7

10

CONNECTOR: B-32

HARNESS CONNECTOR:

COMPONENT SIDE

AB

B-32 (B)

16DB400A

COVER

ENGINE

CONTROL

UNIT

AIR

CLEANER

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

MULTIPORT FUEL INJECTION (MFI)

13A-294

STEP 11. Using the oscilloscope, check the No. 3 cylinder 
injector.
(1) Disconnect the intermediate connector B-32 and connect 

the test harness MB991658 between the separated 
connectors.

(2) Connect the oscilloscope probe to injector intermediate 

connector terminal No. 10.

NOTE: When measuring with the ECU side connector, dis-
connect the all ECU connectors and connect check harness 
special tool (MB992044) between the separated connec-
tors. Then connect an oscilloscope probe to the check har-
ness connector terminal No. 34.

(3) Start the engine and run at idle.

(4) Measure the waveform.

• The waveform should show a normal pattern similar to 

the illustration.

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

Q: Is the waveform normal?

YES : It can be assumed that this malfunction is intermittent. 

Refer to 00E, How to Use Troubleshooting/Inspection 
Service Points 

− How to Cope with Intermittent 

Malfunctions 

P.00-14

.

NO :  Replace the ECU. Then go to Step 12.

STEP 12. Test the EOBD drive cycle.
(1) Carry out a test drive with the drive cycle pattern. Refer to 

Diagnostic Function 

− EOBD Drive Cycle −

P.13A-11

.

(2) Check the diagnostic trouble code (DTC).

Q: Is DTC P0203 set?

YES : Retry the troubleshooting.
NO :  The inspection is complete.

AK303053

3

4

5

8

9

1

2

6

7

10

CONNECTOR: B-32

HARNESS CONNECTOR:

COMPONENT SIDE

AB

B-32 (B)

1 2 3
6 7 8

4 5
9 10

AK203300

OSCILLOSCOPE

MB991658

B-32 INTERMEDIATE

CONNECTOR

AB

AKX01557 AB

A

NORMAL  WAVEFORM

A:INJECTOR DRIVE TIME

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

MULTIPORT FUEL INJECTION (MFI)

13A-295

DTC P0204: Injector Circuit Malfunction - Cylinder 4. 

.

CIRCUIT OPERATION

• Refer to DTC P0300 - Random/Multiple Misfire- 

P.13A-330

 and Misfire Cylinder 4- 

P.13A-340

.

• The injector power is supplied from the MPI relay 

(terminal No. 4).

• The ECU controls the injector by turning the 

power transistor in the ECU "ON" and "OFF".

.

TECHNICAL DESCRIPTION

• The amount of fuel injected by the injector is con-

trolled by the amount of continuity time the coil is 
grounded by the ECU.

• A surge voltage is generated when the injectors 

are switched on/off.

• The ECU monitors this surge voltage.

.

DTC SET CONDITIONS <Circuit continuity 

− open circuit and shorted low>

Check Conditions

• Battery voltage is between 9.04 and 16.01vols.

• Engine speed is above 801 r/min.

Judgment Criteria

• IC internal test (open circuit, short to earth, short 

to battery).

• MIL on after 2 drive cycles.

• Misfire present.

.

EOBD DRIVE CYCLE PATTERN

Refer to Diagnostic Function 

− EOBD Drive Cycle − 

P.13A-11

.

.

AK303109

CONNECTOR: B-27

B-27 (GR)

AB

1

2

3

4

1

2

3

4

1

2

3

4

1

2

3

4

AK303014

CONNECTOR: B-17X

MFI RELAY

MFI RELAY

FRONT OF VEHICLE

B-17X

AB

16DB400A

COVER

ENGINE

CONTROL

UNIT

AIR

CLEANER