Mitsubishi Galant 9G. Manual - part 1048

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-492

STEP 11. Using the oscilloscope, check the No. 1 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 to No.5.
NOTE: When measuring with the PCM side connector, dis-
connect the all PCM connectors and connect check har-
ness special tool (MB991923) between the separated 
connectors. Then connect an oscilloscope probe to the 
check harness connector terminal No.153.

(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 00, How to Use Troubleshooting/Inspection 
Service Points 

− How to Cope with Intermittent 

Malfunctions 

P.00-14

.

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

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

Diagnostic Function 

− OBD-II Drive Cycle − Procedure 6 − 

Other Monitor 

P.13B-6

.

(2) Check the diagnostic trouble code (DTC).
Q: Is DTC P0201 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

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-493

DTC P0202: Injector Circuit Malfunction - Cylinder 2

CAUTION

If DTC P0202 has been set, TCL related DTC 
U1120 is also set. After P0202 has been diag-
nosed, don't forget to erase DTC U1120.

AK400908

YELLO

W

-RED

RED

146

POWERTRAIN CONTROL
MODULE (PCM)

1

2

INJECTOR
NO. 2

1

      B-23

Injector Circuit - Cylinder 2

121 122 123 124 125 126 127

128 129 130 131 132 133

134 135 136 137 138 139 140

141 142 143 144 145 146

147 148 149 150 151 152 153

2

3

4

MFI
RELAY

TO PCM

RED-

WHITE

RED-

WHITE

BATTERY

B-17X

1

2

3

4

B-30

(MU802062)

2

1

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-494

.

CIRCUIT OPERATION

• The injector power is supplied from the MFI relay 

(terminal No. 4).

• The PCM controls the injector by turning the 

power transistor in the PCM "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 PCM.

• A surge voltage is generated when the injectors 

are driven and the current flowing to the injector 
coil is shut off.

• The PCM checks this surge voltage.

.

DESCRIPTIONS OF MONITOR METHODS

Off-surge does not occur after injector is operated.

.

MONITOR EXECUTION

Continuous

.

MONITOR EXECUTION CONDITIONS 
(Other monitor and Sensor)

Other Monitor (There is no temporary DTC stored 

in memory for the item monitored below)

• Not applicable

Sensor (The sensor below is determined to be 

normal)

• Not applicable

.

AK303102

CONNECTOR: B-30

B-30 (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

AK303059

CONNECTOR: B-23

PCM

AB

AIR CLEANER

B-23

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-495

DTC SET CONDITIONS <Circuit continuity 

− open circuit and shorted low>

Logic Flow Chart

.

Check Conditions

• Engine is running.

Judgment Criteria

• The supply voltage is 3 volts or less without the 

injector driving.

.

START

END

NO

NO

NO

YES

YES

YES

MALFUNCTION

GOOD

MONITORING

CONDITIONS

CONTINUOUS

FAILURE FOR 2secs

INJ. SURGE V

<= 3 V

AK401614