Mitsubishi 380. Manual - part 629

MULTIPORT FUEL INJECTION (MPI) DIAGNOSIS

MULTIPORT FUEL INJECTION (MPI) <3.8L ENGINE>

13A-608

STEP 5. Measure the ignition switch-IG signal voltage at 
ECU harness side connector B-21.
(1) Disconnect the connector B-21 and measure at the harness 

side.

(2) Turn the ignition switch to the "ON" position.

(3) Measure the voltage between terminal No. 70 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 :  Check harness connector C-214 and C-215 at 

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

P.00E-2

. If intermediate 

connectors are in good condition, repair harness wire 
between ignition switch connector C-308 (terminal 
No. 2) and ECU connector B-21 (terminal No. 70) 
because of open circuit. Then confirm that the 
malfunction symptom is eliminated.

16DB400A

COVER

ENGINE

CONTROL

UNIT

AIR

CLEANER

03DB161A

B-21 HARNESS 

CONNECTOR 

MULTIPORT FUEL INJECTION (MPI) DIAGNOSIS

MULTIPORT FUEL INJECTION (MPI) <3.8L ENGINE>

13A-609

STEP 6. Measure the backup power supply voltage at ECU 
harness side connector B-21.
(1) Disconnect the connector B-21 and measure at the harness 

side.

(2) Measure the voltage between terminal No. 16 and ground.

• Voltage should be battery positive voltage.

Q: Is battery positive voltage (approximately 12 volts) 

present?
YES : Go to Step 7.
NO :  Repair harness wire between relay box (9) and ECU 

connector B-21 (terminal No. 16) because of short 
circuit. Then confirm that the malfunction symptom is 
eliminated.

16DB400A

COVER

ENGINE

CONTROL

UNIT

AIR

CLEANER

03DB162A

B-21 HARNESS 

CONNECTOR 

MULTIPORT FUEL INJECTION (MPI) DIAGNOSIS

MULTIPORT FUEL INJECTION (MPI) <3.8L ENGINE>

13A-610

STEP 7. Check for continuity at ECU harness side 
connector B-21.
(1) Disconnect the connector B-21 and measure at the harness 

side.

(2) Check for the continuity between terminals (No. 04, No. 06) 

and ground.

• Should be less than 2 ohms.

Q: Does continuity exist?

YES : Go to Step 8.
NO :  Check harness connector A-14 at grounding 

connector for damage, and repair or replace as 
required. Refer to, GROUP 00E, Harness Connector 
Inspection. If grounding connector is good condition, 
repair harness wire between ECU connector B-21 
(terminal No. 04, No. 06) and ground because of open 
circuit. Then confirm that the malfunction symptom is 
eliminated.

16DB400A

COVER

ENGINE

CONTROL

UNIT

AIR

CLEANER

03DB163A

B-21 HARNESS 

CONNECTOR 

MULTIPORT FUEL INJECTION (MPI) DIAGNOSIS

MULTIPORT FUEL INJECTION (MPI) <3.8L ENGINE>

13A-611

STEP 8. 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) Measure the voltage between terminal No. 24 and ground.

• Voltage should be battery positive voltage.

Q: Is battery positive voltage (approximately 12 volts) 

present?
YES : Go to Step 9.
NO :  Repair harness wire between MPI relay connector 

B-17X (terminal No. 3) and ECU connector B-20 
(terminal No. 24) because of open circuit. Then 
confirm that the malfunction symptom is eliminated.

16DB400A

COVER

ENGINE

CONTROL

UNIT

AIR

CLEANER

03DB164A

B-20 HARNESS 

CONNECTOR