Mitsubishi Colt Ralliart. Manual - part 34

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI) <4A9>

13A-90

OPERATION

• Power is supplied to the injector (terminal No. 1) 

from the engine control relay (terminal No. 4).

• The engine-ECU <M/T> or engine-CVT-ECU 

<CVT> (terminal No. 8) makes the power transis-
tor in the unit be in ON position, and that makes 
currents go on the injector (terminal No. 2).

FUNCTION

• The engine-ECU <M/T> or engine-CVT-ECU 

<CVT> controls the power supply interval of the 
injector.

• The fuel injection amount of the injector depends 

on the power supply interval.

TROUBLE JUDGMENT

Check Conditions

• Engine speed is between 50 and 1000 r/min.

• Throttle position sensor (main) output is 1.0 V or 

less.

• Injector operation (by carrying out actuator test) 

is not in progress.

Judgment Criterion

• Injector coil surge voltage (battery positive volt-

age +2 V) has not been detected for 4 seconds.

PROBABLE CAUSES

• Failed No. 1 injector

• Open/short circuit in No. 1 injector circuit or loose 

connector contact

• Failed engine-ECU <M/T> or engine-CVT-ECU 

<CVT>

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III actuator test

• Item 01: No. 1 injector

OK: Idling state varies.

Q: Is the check result normal?

YES : 

Intermittent malfunction (Refer to GROUP 

00 

− How to Use 

Troubleshooting/Inspection Service Points 

− 

How to Cope with Intermittent Malfunctions 

P.00-13

).

NO : 

Go to Step 2 .

STEP 2. Connector check: A-102 No. 1 injector 
connector

Q: Is the check result normal?

YES : 

Go to Step 3 .

NO : 

Repair or replace the connector.

STEP 3. Perform resistance measurement at 
A-102 No. 1 injector connector.

• Disconnect connector, and measure at injector 

side.

• Resistance between terminal No. 1 and No. 2.

OK: 14 

− 15 Ω (at 20°C)

Q: Is the check result normal?

YES : 

Go to Step 4 .

NO : 

Replace No. 1 injector.

AK402147

M

1

2

A-102 (G)

Connector: A-102

AC

A-102 Harness side

connector

AK402164

1 2

A-102 (G)

Connector: A-102

AC

A-102 Equipment side

connector

Main

Index

Group

TOC

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI) <4A9>

13A-91

STEP 4. Perform voltage measurement at A-102 
No. 1 injector connector.

• Disconnect connector, and measure at harness 

side.

• Ignition switch: ON

• Voltage between terminal No. 1 and earth.

OK: System voltage

Q: Is the check result normal?

YES : 

Go to Step 6 .

NO : 

Go to Step 5 .

STEP 5. Connector check: B-106 engine control 
relay connector

Q: Is the check result normal?

YES : 

Check intermediate connector A-17 and 

B-112, and repair if necessary. If 
intermediate connectors are normal, check 
and repair harness between B-106 (terminal 
No. 4) engine control relay connector and 
A-102 (terminal No. 1) No. 1 injector 
connector.

• Check power supply line for 

open/short circuit.

NO : 

Repair or replace the connector.

AK402147

M

1

2

A-102 (G)

Connector: A-102

AC

A-102 Harness side

connector

3

2

1

4

AK402060

B-106
J/B side 
connector

B-106

Connector: B-106
J/B (front side)

AC

AK402147

M

1

2

A-102 (G)

Connector: A-102

AC

A-102 Harness side

connector

Main

Index

Group

TOC

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI) <4A9>

13A-92

STEP 6. Connector check: A-114 engine-ECU 
connector or engine-CVT-ECU connector

Q: Is the check result normal?

YES : 

Go to Step 7 .

NO : 

Repair or replace the connector.

STEP 7. Check harness between B-106 (terminal 
No. 4) engine control relay connector and A-102 
(terminal No. 1) No. 1 injector connector.

NOTE: Before checking harness, check intermediate 
connectors A-17 and B-112, and repair if necessary.

• Check power supply line for damage.

Q: Is the check result normal?

YES : 

Go to Step 8 . 

NO : 

Repair the damaged harness wire.

AK402745

6

4

2

5

3

1

9

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L

AD

A-114

Connector: 

A-114

Harness side connector

Engine-ECU <M/T> or
engine-CVT-ECU <CVT>

Battery

3

2

1

4

AK402060

B-106
J/B side 
connector

B-106

Connector: B-106
J/B (front side)

AC

AK402147

M

1

2

A-102 (G)

Connector: A-102

AC

A-102 Harness side

connector

Main

Index

Group

TOC

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI) <4A9>

13A-93

STEP 8. Check harness between A-102 (terminal 
No. 2) No. 1 injector connector and A-114 
(terminal No. 8) engine-ECU connector or 
engine-CVT-ECU connector.

• Check output line for open/short circuit and dam-

age.

Q: Is the check result normal?

YES : 

Go to Step 9 .

NO : 

Repair the damaged harness wire.

STEP 9. Perform signal wave pattern 
measurement at A-114 engine-ECU connector or 
engine-CVT-ECU connector (Using an 
oscilloscope).

• Disconnect engine-ECU connector or 

engine-CVT-ECU connector, and connect special 
tool power plant ECU check harness 
(MB991987), and then measure the voltage on 
the check connector.

• Engine: Idling

• Transmission: P range

• Voltage between terminal No. 8 and earth.

OK: Waveforms should be display on 
Inspection procedure using an oscilloscope 
(Refer to 

P.13A-348

).

Q: Is the check result normal?

YES : 

Intermittent malfunction (Refer to GROUP 

00 

− How to Use 

Troubleshooting/Inspection Service Points 

− 

How to Cope with Intermittent Malfunctions 

P.00-13

).

NO : 

Replace engine-ECU <M/T> or 
engine-CVT-ECU <CVT>.

AK402147

M

1

2

A-102 (G)

Connector: A-102

AC

A-102 Harness side

connector

AK402745

6

4

2

5

3

1

9

7

8

10

11

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64

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66

L

AD

A-114

Connector: 

A-114

Harness side connector

Engine-ECU <M/T> or
engine-CVT-ECU <CVT>

Battery

AK402745

6

4

2

5

3

1

9

7

8

10

11

12

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66

L

AE

A-114

Connector: 

A-114

Engine-ECU <M/T> or
engine-CVT-ECU <CVT>

Battery

A-114 Special tool power plant ECU check 
harness

Main

Index

Group

TOC