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Mitsubishi Eclipse. Manual - part 283

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <2.4L>

13A-625

DTC P0506: Idle Control System RPM Lower Than Expected

AK101522

23 24 25 26

5 6

7 8

13
27

14
28

15
29

17
30

18
31

19
32

20
33

22
34

23
35

1 2
4 5 6

RED

WHITE

RED

WHITE

RED

WHITE

RED

GREEN-BL

ACK

GREEN-RED

GREEN-

WHITE

ACK

-YELL

C-49 <M/T>
(MU803773)

C-50 <A/T>
(MU803784)

B-34

IDLE AIR
CONTROL (IAC)
MOTOR

BATTERY

Idle Air Control (IAC) Motor Circuit

MFI
RELAY

ENGINE CONTROL
MODULE (ECM) <M/T>
OR
POWERTRAIN CONTROL
MODULE (PCM) <A/T>

4 <M/T>
14 <A/T>

17 <M/T>
28 <A/T>

5 <M/T>
15 <A/T>

18 <M/T>
29 <A/T>

3 4

1 2

A-18X

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <2.4L>

13A-626

CIRCUIT OPERATION

• The idle air control motor power is supplied from

the MFI relay (terminal No. 4).

• The ECM (terminals No. 4, No. 5, No. 17, No. 18)

<M/T> or PCM (terminals No. 14, No. 15, No. 28,
No. 29) <A/T> drives the stepper motor by
sequentially turning "ON" the power transistors in
the ECM <M/T> or PCM <A/T> and providing
ground to the idle air control motor (terminals No.
1, No. 3, No. 4, No. 6).

TECHNICAL DESCRIPTION

• The amount of air taken in during idling is regu-

lated 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 ECM <M/T> or PCM <A/T> checks the differ-

ence between the actual engine speed and the
target engine speed.

DESCRIPTIONS OF MONITOR METHODS
Difference between actual and target idle speed is

over the specified value.

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)

• Misfire monitor

• Exhaust gas recirculation (EGR) system monitor

• Fuel system monitor

Sensor (The sensor below is determined to be

normal)

• Volume airflow sensor

• Engine coolant temperature sensor

• Intake air temperature sensor

• Barometric pressure sensor

• Throttle position sensor

AK300056

CONNECTOR: B-34

IDLE AIR
CONTROL MOTOR

B-34 (B)

AK300060

ECM

CONNECTOR: C-49 <M/T>

C-49 (G)

AK300060AD

C-50 (GR)

PCM

CONNECTOR: C-50 <A/T>

AK300121

MFI RELAY

CONNECTOR: A-18X

A-18X

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <2.4L>

13A-627

DTC SET CONDITIONS

Logic Flow Chart

Check Conditions

• Under the closed loop idle speed control.

• Engine coolant temperature is more than 77°C

(171

°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 (22.4

in.Hg).

• Intake air temperature is higher than −10°C

(14

°F).

• 25 seconds have elapsed from the start of the

previous monitoring.

• Target idle air control motor position is more than

100 steps.

Judgment Criteria

• The actual idle speed is more than 100 r/min

lower than the target idle speed for 12 seconds.

OBD-ll DRIVE CYCLE PATTERN
Refer to Diagnostic Function

− OBD-ll Drive Cycle −

Procedure 6

− Other Monitor

P.13A-5

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

harness damage, or connector damage.

• ECM failed. <M/T>

• PCM failed. <A/T>

DIAGNOSIS

Required Special Tools:

• MB991958 (MUT-III Sub Assembly)

• MB991824: V.C.I.

END

YES

MALFUNCTION

GOOD

START

CALCULATE

MONITORING

CONDITIONS

Ne = (ACTUAL-Ne) - (TARGET-Ne)

Ne: ENGINE SPEED

Ne < -100 r/min OR

> 200 r/min

HAVE 10secs PASSED?

AK204002

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <2.4L>

13A-628

• MB991827: USB Cable

• MB991911: Main Harness B

• MB991709: Test harness Set

STEP 1. Using scan tool MB991958, read the diagnostic
trouble code (DTC).

CAUTION

To prevent damage to scan tool MB991958, always turn the
ignition switch to the "LOCK" (OFF) position before con-
necting or disconnecting scan tool MB991958.
(1) Connect scan tool MB991958 to the data link connector.
(2) Turn the ignition switch to the "ON" position.
(3) Set scan tool MB991958, 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.13A-24

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.13A-926

. Then go to Step 14.

NO : Go to Step 3.

STEP 3. Check connector B-34 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