Mitsubishi 380. Manual - part 633

MULTIPORT FUEL INJECTION (MPI) DIAGNOSIS

MULTIPORT FUEL INJECTION (MPI) <3.8L ENGINE>

13A-624

INSPECTION PROCEDURE 26: Ignition Switch-ST System and Transmission Inhibitor Switch System

.

COMMENT

• If the selector lever is moved to "P" or "N" range 

and the ignition switch is turned to "START" posi-
tion, battery positive voltage is supplied to ECU 
(terminal No. 9) through the ignition switch and 
transmission inhibitor switch. Because of this, the 
ECU detects that the engine is cranking. 

• The transmission inhibitor switch detects the 

transmission inhibitor (P, N or other ranges) and 
converts it to a voltage signal (high or low). Then 
the transmission inhibitor switch sends that signal 
to the ECU. 

If the selector lever is moved to "P" or "N" range 
with the ignition switch turned on (except 
"START" position), continuity will exist between 
the ECU and ground through the transmission 
inhibitor switch and starter motor. The terminal 
voltage of the ECU will become low. If the selec-
tor lever is moved to the other ranges, continuity 
will be lost between the ECU and ground. The 
terminal voltage of the ECU will become high. 

.

AK303268AB

TRANSMISSION

RANGE SWITCH

CONNECTOR: B-110

B-110 (B)

16DB400A

COVER

ENGINE

CONTROL

UNIT

AIR

CLEANER

AK303148

CONNECTOR: A-13

AB

A-13(GR)

03DB171A

CONNECTOR: C-29

C-29

03DB170A

CONNECTOR: C-308

C-308

MULTIPORT FUEL INJECTION (MPI) DIAGNOSIS

MULTIPORT FUEL INJECTION (MPI) <3.8L ENGINE>

13A-625

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

• Malfunction of the ignition switch.

• Malfunction of the transmission inhibitor switch.

• Improper connector contact, open circuit or 

short-circuit in the 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

STEP 1. Check connector B-110 at transmission inhibitor 
switch 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.

STEP 2. Check the transmission inhibitor switch.
Refer to GROUP 23A, On-vehicle Service 

− Essential Service − 

Transmission Inhibitor Switch Continuity Check 

P.23A-294

.

Q: Are there any abnormalities?

YES : Repair or replace it. Then confirm that the malfunction 

symptom is eliminated.

NO :  Go to Step 3.

8

9

3

4

5

1

2

6

7

10

AK303269AB

TRANSMISSION

RANGE SWITCH

CONNECTOR: B-110

B-110 (B)

HARNESS

CONNECTOR:

COMPONENT SIDE

MULTIPORT FUEL INJECTION (MPI) DIAGNOSIS

MULTIPORT FUEL INJECTION (MPI) <3.8L ENGINE>

13A-626

STEP 3. Measure the power supply voltage at transmission 
inhibitor switch connector B-110.
(1) Disconnect the connector B-110 and measure at the 

harness side.

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

(3) Measure the voltage between terminal No. 10 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 4.
NO :  Check connector A-13 and C-29 at intermediate 

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

P.00E-2

. If intermediate connector are in 

good condition, repair harness wire between ignition 
switch connector C-308 (terminal No. 5) and 
transmission inhibitor switch connector B-110 
(terminal No. 10) because of open circuit. Then 
confirm that the malfunction symptom is eliminated.

STEP 4. Check connector B-20 at ECU for damage.
Q: Is the connector in good condition?

YES : Go to Step 5.
NO :  Repair or replace it. Refer to GROUP 00E, Harness 

Connector Inspection 

P.00E-2

. Then confirm that the 

malfunction symptom is eliminated.

8

9

3

4

5

1

2

6

7

10

AK303269AB

TRANSMISSION

RANGE SWITCH

CONNECTOR: B-110

B-110 (B)

HARNESS

CONNECTOR:

COMPONENT SIDE

8

9

3

4

5

1

2

6

7

10

AK303270

B-110 HARNESS 

CONNECTOR: 

COMPONENT SIDE

AB

16DB400A

COVER

ENGINE

CONTROL

UNIT

AIR

CLEANER

MULTIPORT FUEL INJECTION (MPI) DIAGNOSIS

MULTIPORT FUEL INJECTION (MPI) <3.8L ENGINE>

13A-627

STEP 5. Check for open circuit and short circuit to ground 
and harness damage between transmission inhibitor 
switch connector B-110 (terminal No. 9) and ECU 
connector B-20 (terminal No. 09).
Q: Is the harness wire in good condition?

YES : Replace the ECU. Then confirm that the malfunction 

symptom is eliminated.

NO :  Repair it. Then confirm that the malfunction symptom 

is eliminated.

8

9

3

4

5

1

2

6

7

10

AK303269AB

TRANSMISSION

RANGE SWITCH

CONNECTOR: B-110

B-110 (B)

HARNESS

CONNECTOR:

COMPONENT SIDE

16DB400A

COVER

ENGINE

CONTROL

UNIT

AIR

CLEANER