Mitsubishi Galant. Manual — part 236

MULTIPORT FUEL INJECTION(MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.0L>

13B-169

STEP 1. Check connector B-28 at the left bank heated
oxygen sensor (front) for damage.
Q: Is the harness 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 go to Step 12.

STEP 2. Check the left bank heated oxygen sensor (front).
(1) Disconnect left bank heated oxygen sensor (front)

connector B-28 and connect test harness special tool,
MD998464, to the connector on the left bank heated
oxygen (front) sensor side.

(2) Measure the resistance between heated oxygen sensor

connector terminal 1 (red clip) and terminal 3 (blue clip).

Standard value: 4.5

−−−−

8.0 ohm [at 20

°°°°

C (68

°°°°

F)]

Q: Is the resistance normal?

YES : Go to Step 3.
NO : Replace the left bank heated oxygen sensor (front).

Then go to Step 12.

STEP 3. Check the power supply voltage at left bank
heated oxygen sensor (front) harness side connector B-28.
(1) Disconnect the connector B-28 and measure at the harness

side.

(2) Turn the ignition switch to the "ON" position.
(3) Measure the voltage between terminal 1 and ground.

•

Voltage should be battery positive voltage.

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

Q: Is the voltage normal?

YES : Go to Step 5.
NO : Go to Step 4.

AK000619

CONNECTOR:B-28

AB

ACX02489 AF

CONNECTOR:B-28

LEFT BANK
HEATED OXYGEN
SENSOR (FRONT)

AKX01624

HEATED
OXYGEN
SENSOR
EQUIPMENT
SIDE
CONNECTOR

MD998464

BLUE

RED

AC

AKX01498

B-28 HARNESS
SIDE CONNECTOR

2

4

1

3

AM

MULTIPORT FUEL INJECTION(MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.0L>

13B-170

STEP 4. Check connector A-21X at the MFI relay for
damage.
Q: Is the connector in good condition?

YES : Repair harness wire between MFI relay connector A-

21X terminal 1 and left bank heated oxygen sensor
(front) connector B-28 terminal 1 because of open
circuit or short circuit to ground. Then go to Step 12.

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

Connector Inspection(

P.00E-2

). Then go to Step 12.

STEP 5. Check the power supply voltage at PCM connector
C-39 by backprobing.
(1) Do not disconnect the connector C-39.
(2) Turn the ignition switch to the "ON" position.
(3) Measure the voltage between terminal 3 and ground by

backprobing.

•

Voltage should be battery positive voltage.

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

Q: Is the voltage normal?

YES : Go to Step 8.
NO : Go to Step 6.

STEP 6. Check connector C-39 at PCM for damage.
Q: Is the connector in good condition?

YES : Go to Step 7.
NO : Repair or replace it. Refer to GROUP 00E, Harness

Connector Inspection(

P.00E-2

). Then go to Step 12.

AK000555AB

CONNECTOR : A-21X

MFI RELAY

AKX01540

AKX01540

1

2

3 4

5 6

7 8

9 10 1112 13 141516 1718 19 20 212223

24 25

26 2728 29

303132 33

3435

AE

C-39 CONNECTOR
HARNESS SIDE VIEW

AK000280

CONNECTOR : C-39

PCM

AW

MULTIPORT FUEL INJECTION(MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.0L>

13B-171

STEP 7. Check for open circuit or short circuit to ground
between left bank heated oxygen sensor (front) connector
B-28 terminal 3 and PCM connector C-39 terminal 3.
Q: Is the harness wire in good condition?

YES : Replace the PCM. Then go to Step 12.
NO : Repair it. Then go to Step 12.

STEP 8. Check connector C-39 at PCM for damage.
Q: Is the connector in good condition?

YES : Go to Step 9.
NO : Repair or replace it. Refer to GROUP 00E, Harness

Connector Inspection(

P.00E-2

). Then go to Step 12.

AK000619

CONNECTOR:B-28

AB

AK000280

CONNECTOR : C-39

PCM

AW

AK000280

CONNECTOR : C-39

PCM

AW

MULTIPORT FUEL INJECTION(MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.0L>

13B-172

STEP 9. Check for harness damage between MFI relay
connector A-21X terminal 1 and left bank heated oxygen
sensor (front) connector B-28 terminal 1.
Q: Is the harness wire in good condition?

YES : Go to Step 10.
NO : Repair it. Then go to Step 12.

STEP 10. Check for harness damage between left bank
heated oxygen sensor (front) connector B-28 terminal 3
and PCM connector C-39 terminal 3.
Q: Is the harness wire in good condition?

YES : Go to Step 11.
NO : Repair it. Then go to Step 12.

AK000555AB

CONNECTOR : A-21X

MFI RELAY

AK000619

CONNECTOR:B-28

AB

AK000619

CONNECTOR:B-28

AB

AK000280

CONNECTOR : C-39

PCM

AW