Mitsubishi Galant. Manual — part 230

MULTIPORT FUEL INJECTION(MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.0L>

13B-145

CIRCUIT OPERATION

•

Power is supplied from the MFI relay (terminal 1)
to the right bank heated oxygen sensor (rear)
heater.

•

The PCM (terminal 27) controls continuity to the
right bank heated oxygen sensor (rear) heater by
turning the power transistor in the PCM "ON" and
"OFF."

BACKGROUND

•

The PCM checks whether the heater current is
within a specified range when the heater is
energized.

DTC SET CONDITIONS

Check Conditions

•

Engine coolant temperature is higher than 20

°

C

(68

°

F).

•

While the right bank heated oxygen sensor (rear)
heater is on.

•

Battery positive voltage is at between 11 and 16
volts.

Judgment Criteria

•

Heater current of the right bank heated oxygen
sensor (rear) heater has continued to be lower
than 0.2 ampere or higher than 3.5 ampere for 6
seconds.

•

Only one monitor during one drive cycle

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

•

Open or shorted right bank heated oxygen
sensor (rear) heater circuit.

•

Open circuit in right bank heated oxygen sensor
(rear) heater.

•

PCM failed.

DIAGNOSIS

Required Special Tools
MB991316: Test Harness

ACX02493AG

CONNECTOR:B-31

RIGHT BANK
HEATED OXYGEN
SENSOR (REAR)

AK000555AB

CONNECTOR : A-21X

MFI RELAY

AK000280

CONNECTOR : C-39

PCM

AW

MULTIPORT FUEL INJECTION(MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.0L>

13B-146

STEP 1. Check connector B-31 at the right bank heated
oxygen sensor (rear) 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 go to Step 12.

STEP 2. Check the right bank heated oxygen sensor (rear).
(1) Disconnect right bank heated oxygen sensor (rear)

connector B-31 and connect test harness special tool,
MB991316, to the connector on the right bank heated
oxygen (rear) sensor side.

(2) Measure the resistance between heated oxygen sensor

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

Standard value: 11

−−−−

18 ohm [at 20

°°°°

C (68

°°°°

F)]

Q: Is the resistance normal?

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

Then go to Step 12.

STEP 3. Check the power supply voltage at right bank
heated oxygen sensor (rear) harness side connector B-31.
(1) Disconnect the connector B-31 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.

AK000617

CONNECTOR:B-31

AC

ACX02493AG

CONNECTOR:B-31

RIGHT BANK
HEATED OXYGEN
SENSOR (REAR)

AKX01624 AB

MB991316

HEATED
OXYGEN
SENSOR
EQUIPMENT
SIDE
CONNECTOR

BLUE

RED

AKX01496

B-31 HARNESS
SIDE CONNECTOR

2

4

1

3

AG

MULTIPORT FUEL INJECTION(MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.0L>

13B-147

STEP 4. Check harness 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 right bank heated oxygen sensor
(rear) connector B-31 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 27 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

AKX01537

AKX01537

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-148

STEP 7. Check for open circuit or short circuit to ground
between right bank heated oxygen sensor (rear) connector
B-31 terminal 3 and PCM connector C-39 terminal 27.
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.

AK000617

CONNECTOR:B-33

AB

AK000280

CONNECTOR : C-39

PCM

AW

AK000280

CONNECTOR : C-39

PCM

AW