Mitsubishi Eclipse / Eclipse Spyder (2000-2002). Service and repair manual — part 148

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <2.4L ENGINE>

13A-291

CIRCUIT OPERATION

•

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

•

The ECM (terminals 4, 5, 17, 18) <M/T> or PCM
(terminals 14, 15, 28, 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 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 ECM <M/T> or PCM <A/T> 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.

•

ECM failed. <M/T>

•

PCM failed. <A/T>

DIAGNOSIS

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

ACX02519 AI

IDLE AIR
CONTROL MOTOR

CONNECTOR:B-34

AK000280

C-49,C-50

ECM<M/T>
OR
PCM<A/T>

CONNECTORS:C-49<M/T>,C-50<A/T>

BC

AK000226

AK000226AB

CONNECTOR : A-21X

MFI RELAY

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <2.4L ENGINE>

13A-292

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.13A-20

).

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-472

). 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 (

P.00E-2

). Then go to Step 14.

AKX01177

16 PIN

MB991502

AB

ACX02519 AI

IDLE AIR
CONTROL MOTOR

CONNECTOR:B-34

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <2.4L ENGINE>

13A-293

STEP 4. Check the idle air control motor coil resistance.
(1) Disconnect the idle air control motor connector B-34.
(2) Measure the resistance between idle air control motor

connector terminal 2 and either terminal 1 or terminal 3.

Standard value: 28

−

33 ohm [at 20

°

C (68

°

F)]

(3) Measure the resistance between idle air control motor

connector terminal 5 and either terminal 4 or terminal 6.

Standard value: 28

−

33 ohm [at 20

°

C (68

°

F)]

Q: Is the resistance normal?

YES : Go to Step 5.
NO : Replace the idle air control motor. Then go to Step 14.

STEP 5. Check the power supply voltage at idle air control
motor harness side connector B-34.
(1) Disconnect the connector B-34 and measure at the harness

side.

(2) Turn the ignition switch to the "ON" position.
(3) Measure the voltage between terminal 2, 5 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 7.
NO : Go to Step 6.

ACX02519 AI

IDLE AIR
CONTROL MOTOR

CONNECTOR:B-34

AKX01561

1 2 3
4 5 6

1 2 3
4 5 6

AB

AKX01428

1

2

3

5 4

6

B-34 HARNESS
SIDE CONNECTOR

AF

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI) <2.4L ENGINE>

13A-294

STEP 6. Check connector A-21X at MFI relay for damage.
Q: Is the connector in good condition?

YES : Repair harness wire between MFI relay connector A-

21X terminal 1 and idle air control motor connector B-
34 terminal 2, 5 because of open circuit or short circuit
to ground. Then go to Step 14.

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

Connector Inspection (

P.00E-2

). Then go to Step 14.

STEP 7. Check the power supply voltage at ECM connector
C-49 <M/T> or PCM connector C-50 <A/T> by backprobing
(1) Do not disconnect the connector C-49 <M/T> or C-50 <A/

T>.

(2) Measure the voltage between terminal (4, 5, 17, 18) <M/T>

or (14, 15, 28, 29) <A/T> and ground by backprobing.

•

The voltage is 1V or lower for approximately 3 seconds,
then changes to the battery positive voltage when the
Ignition switch is turned from the "LOCK" (OFF) position
to the "ON" position.

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

Q: Is the voltage normal?

YES : Go to Step 10.
NO : Go to Step 8.

STEP 8. Check connector C-49 at ECM <M/T> or connector
C-50 at PCM <A/T> 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 14.

AK000226

AK000226AB

CONNECTOR : A-21X

MFI RELAY

AK000306

10

1 2 3 4 5 6 7 8 9

1112 13

141516171819 20 2122 23242526

AC

<M/T>

C-49 CONNECTOR
HARNESS SIDE VIEW

AK000307

1

2

3 4

5 6

7 8

9 10 11 1213 141516 17 1819 20 21 2223

24 25

2627 2829

30 3132 33

3435

AD

C-50 CONNECTOR
HARNESS SIDE VIEW

<A/T>

AK000280

C-49,C-50

ECM<M/T>
OR
PCM<A/T>

CONNECTORS:C-49<M/T>,C-50<A/T>

BC