Mitsubishi Galant. Manual — part 278

MULTIPORT FUEL INJECTION(MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.0L>

13B-337

DTC P0500: Vehicle Speed Sensor Malfunction <A/T>

TECHNICAL DESCRIPTION

•

When a malfunction of the vehicle speed sensor
is detected, the transaxle control CPU inside the
powertrain control module (PCM) outputs a
malfunction signal to the engine control CPU in
the PCM.

DTC SET CONDITIONS

Check Conditions, Judgment Criteria

•

Vehicle speed sensor failure signal is input to the
engine control CPU from the transaxle control
CPU.

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

•

Vehicle speed sensor failed.

•

Open or shorted vehicle speed sensor circuit, or
loose connector.

•

PCM failed.

DIAGNOSIS

Required Special Tools
MB991502: Scan Tool (MUT-II)

STEP 1. Using scan tool MB991502, read the A/T
diagnostic trouble code (DTC).

CAUTION

To prevent damage to scan tool MB991502, always turn the
ignition switch to the "LOCK"(OFF) position before
connecting or disconnecting scan tool MB991502.
(1) Connect scan tool MB991502 to the data link connector.
(2) Turn the ignition switch to the "ON" position.
(3) Check the A/T-DTC.
(4) Turn the ignition switch to the "LOCK"(OFF) position.

Q: Is the A/T-DTC is output?

YES : Refer to GROUP 23A, Automatic Transaxle

Diagnosis

−

Diagnostic Trouble Code Chart(

P.23A-37

).

NO : If DTC P0500 is output again after the MFI-DTC has

been erased, replace the PCM. Then check that the
DTC P0500 does not reset.

AC003081 AB

16 PIN

MB991502

MULTIPORT FUEL INJECTION(MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.0L>

13B-338

DTC P0506: Idle Control System RPM Lower Than Expected

AK000515

1 2
3 4

1 2
4 5 6

3

RED-

WHITE

RED-

WHITE

RED-

WHITE

RED

RED

RED

RED-BLA

CK

BR

O

WN-WHITE

GREEN-YELLO

W

BLA

CK-YELLO

W

B-06

IDLE AIR
CONTROL(IAC)
MOTOR

A-21X

BATTERY

MFI
RELAY

1

1

2

2

3

3

4

4

5

6

POWERTRAIN CONTROL
MODULE(PCM)

14

28

15

29

C-39
(MU803784)

2

3 4

5 6

7 8

9

11 12 13 14 15 16 17 18 19 20

30

21 22 23

24 25

26 27 28 29

3132 33

34 35

1

10

MULTIPORT FUEL INJECTION(MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.0L>

13B-339

CIRCUIT OPERATION

•

The idle air control motor power is supplied from
the MFI relay (terminal 1).

•

The PCM (terminals 14, 15, 28, 29) drives the
stepper motor by sequentially turning "ON" the
power transistors in the PCM and providing
ground to the idle air control motor (terminals 1,
3, 4, 6).

TECHNICAL DESCRIPTION

•

The amount of air taken in during idling is
regulated by the opening and closing of the servo
valve located in the air passage that bypasses
the throttle body.

•

If there is a malfunction of the IAC system, the
actual engine speed will not be identical to the
target engine speed.

•

The PCM checks the difference between the
actual engine speed and the target engine speed.

DTC SET CONDITIONS

Check Conditions

•

Under the closed loop idle speed control.

•

The engine coolant temperature is more than
approximately 82

°

C (180

°

F).

•

Battery positive voltage is higher than 10 volts.

•

Power steering pressure switch: "OFF."

•

Volumetric efficiency is lower than 40 percent.

•

Barometric pressure is higher than 76 kPa (11
psi).

•

Intake air temperature is higher than -10

°

C (14

°

F).

Judgment Criteria

•

The actual idle speed is more than 100 r/min
lower than the target idle speed for 12 seconds.

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

•

Idle air control motor failed.

•

Open or shorted idle air control motor circuit, or
loose connector.

•

PCM failed.

DIAGNOSIS

Required Special Tools
MB991502: Scan Tool (MUT-II)
MB991709: Test harness

ACX02523AG

IDLE AIR
CONTROL
MOTOR

CONNECTOR:B-06

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-340

STEP 1. Using scan tool MB991502, read the diagnostic
trouble code (DTC).

CAUTION

To prevent damage to scan tool MB991502, always turn the
ignition switch to the "LOCK"(OFF) position before
connecting or disconnecting scan tool MB991502.
(1) Connect scan tool MB991502 to the data link connector.
(2) Turn the ignition switch to the "ON" position.
(3) Set scan tool MB991502, read the DTC.
(4) Turn the ignition switch to the "LOCK"(OFF) position.

Q: Is the diagnostic trouble code other than P0506 output?

YES : Refer to, Diagnostic Trouble Code Chart(

P.13B-19

).

NO : Go to Step 2.

STEP 2. Check the throttle body (throttle valve area)

Q: Is the throttle valve area dirty?

YES : Perform cleaning. Refer to, Throttle body (throttle

valve area) cleaning(

P.13B-520

). Then go to Step 14.

NO : Go to Step 3.

STEP 3. Check connector B-06 at idle air control motor for
damage.
Q: Is the connector in good condition?

YES : Go to Step 4.
NO : Repair or replace it. Refer to GROUP 00E, Harness

Connector Inspection(

P.00E-2

). Then go to Step 14.

AC003081 AB

16 PIN

MB991502

ACX02523AG

IDLE AIR
CONTROL
MOTOR

CONNECTOR:B-06