Mitsubishi 380. Manual - part 551

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

MULTIPORT FUEL INJECTION (MFI)

13A-296

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

• No.4 cylinder injector failed.

• Open or shorted to ground No.4 cylinder injector 

circuit.

• Shorted to battery, No.4 cylinder injector circuit.

• Harness or connector damage.

• 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

• MB991658: Test Harness Set
• MB992044: Power Plant ECU Check Harness

STEP 1. Using diagnostic tool , check actuator test item 
04: No. 4 injector.

CAUTION

To prevent damage to diagnostic tool , always turn the 
ignition switch to the "LOCK" (OFF) position before con-
necting or disconnecting diagnostic tool .
(1) Connect diagnostic tool to the data link connector.
(2) Start the engine and run at idle.
(3) Set diagnostic tool to the actuator testing mode for item 04, 

No. 4 injector.

(4) Warm up the engine to normal operating temperature: 80

°C 

to 95

°C (176°F to 203°F).

• The idle should become slightly rougher.

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

Q: Does the idle vary or engine run "rough"?

YES : It can be assumed 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 the harness connector B-27 at No. 4 
cylinder injector 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 go to Step 10.

00DB076A

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

AK303110

M

1

2

CONNECTOR: B-27

B-27 (GR)

HARNESS CONNECTOR:

COMPONENT SIDE

AB

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

MULTIPORT FUEL INJECTION (MFI)

13A-297

STEP 3. Check the No. 4 cylinder injector.
(1) Disconnect the No.4 cylinder injector connector B-27.

(2) Measure the resistance between injector side connector 

terminal No. 1 and No. 2.

 Standard value: 10.5 

− 13.5 ohms [at 20°C (68°F)]

Q: Is the measured resistance between 10.5 and 13.5 ohms 

[at 20

°C (68°F)]?

YES : Go to Step 4.
NO :  Replace the No. 4 cylinder injector. Then go to Step 

10.

STEP 4. Measure the power supply voltage at No. 4 
cylinder injector connector B-27.
(1) Disconnect connector B-27 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 6.
NO :  Go to Step 5.

AK303110

M

1

2

CONNECTOR: B-27

B-27 (GR)

HARNESS CONNECTOR:

COMPONENT SIDE

AB

AK000559

2

1

INJECTOR SIDE
CONNECTOR

AB

AK303110

M

1

2

CONNECTOR: B-27

B-27 (GR)

HARNESS CONNECTOR:

COMPONENT SIDE

AB

AK303111

1

2

B-27 HARNESS 

CONNECTOR: 

COMPONENT SIDE

AB

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

MULTIPORT FUEL INJECTION (MFI)

13A-298

STEP 5. Check harness connector B-17X at MFI relay for 
damage.
Q: Is the harness connector in good condition?

YES : Repair harness wire between MFI relay connector 

B-17X (terminal No. 4) and No. 4 cylinder injector 
connector B-27 (terminal No. 1) because of open 
circuit or short circuit to ground.

Then go to Step 10.

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

Connector Inspection 

P.00E-2

. Then go to Step 10.

1

2

3

4

AK303017

CONNECTOR: B-17X

FRONT OF VEHICLE

B-17X

AB

HARNESS

CONNECTOR:

COMPONENT SIDE

RELAY BOX

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

MULTIPORT FUEL INJECTION (MFI)

13A-299

STEP 6. Check for harness damage between MFI relay 
connector B-17X (terminal No. 4) and No. 4 cylinder 
injector connector B-27 (terminal No. 1).
Q: Is the harness wire in good condition?

YES : Go to Step 7.
NO :  Repair it. Then go to Step 10.

1

2

3

4

AK303017

CONNECTOR: B-17X

FRONT OF VEHICLE

B-17X

AB

HARNESS

CONNECTOR:

COMPONENT SIDE

RELAY BOX

AK303110

M

1

2

CONNECTOR: B-27

B-27 (GR)

HARNESS CONNECTOR:

COMPONENT SIDE

AB