Mitsubishi Galant (2004+). Manual - part 1444

IGNITION SWITCH

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CHASSIS ELECTRICAL

54A-19

SYMPTOM PROCEDURES

INSPECTION PROCEDURE 1: Communication with Scan Tool MB991958 is Impossible.

MFI
RELAY

POWERTRAIN
CONTROL
MODULE (PCM)

POWER
SUPPLY

JOINT
CONNECTOR (2)

IMMOBILIZER-
ECU

Immobilizer-ECU Power Supply, Ground and PCM CommunicationLine Circuit

IGNITION SWITCH

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CHASSIS ELECTRICAL

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.

CIRCUIT OPERATION
The Immobilizer-ECU is energized by the MFI relay 
when the ignition switch is turned "ON". The PCM 
transmits a signal from scan tool MB991958 to the 
immobilizer-ECU as it is. In the same way, a signal 
from the immobilizer-ECU is also transmitted to scan 
tool MB991958 as it is.

.

TECHNICAL DESCRIPTION (COMMENT)

• This malfunction may be caused by a defective 

immobilizer-ECU, PCM, or a defect in the com-
munication line between the immobilizer-ECU 
and PCM. If this malfunction appears when the 
MFI system and scan tool MB991958 can com-
municate each other, MFI system DTC P0513 will 
reset.

• If the MFI system is normal, the MFI relay can be 

determined as normal. In addition, if the MFI sys-
tem and scan tool MB991958 can communicate 
each other, the circuits between the data link con-
nector and the PCM can determined as normal.
NOTE: If this malfunction appears, MFI system 
DTC P0513 will be output.

.

TROUBLESHOOTING HINTS

• Malfunction of the immobilizer-ECU

• Malfunction of the PCM

• The wiring harness or connectors may have 

loose, corroded, or damaged terminals, or termi-
nals pushed back in the connector

.

DIAGNOSIS

Required Special Tools:

• MB991223: Harness Set

• MB991958: Scan Tool (MUT-III Sub Assembly)

• MB991824: Vehicle Communication Interface (V.C.I.)

• MB991827: MUT-III USB Cable

• MB991911: MUT-III Main Harness A (Vehicles with CAN 

communication system)

AC305210

CONNECTOR: A-13

AS

A-13 (GR)

AC305977

CONNECTOR: B-17X

AM

AC305229AE

CONNECTOR: B-19

B-19 (B)

AC305231

CONNECTORS: C-03, C-29, C-124

CS

C-03

C-29

C-124

IGNITION SWITCH

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CHASSIS ELECTRICAL

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STEP 1. Using scan toll MB991958, read the MFI system 
diagnostic trouble code.

CAUTION

To prevent damage to scan tool MB991958, always turn the 
ignition switch to "LOCK" (OFF) position before connect-
ing or disconnecting scan tool.
 Use scan tool MB991958 to confirm the MFI system DTC.
(1) Connect scan tool MB991958 to the data link connector.
(2) Turn the ignition switch "ON" to position.
(3) Read the MFI system diagnosis code.

NOTE: If the scan tool MB991958 cannot communicate 
with the MFI system, refer to GROUP 13A, MFI Diagnosis 

−

 

Symptom Procedures 

P.13A-944

 or GROUP 13B, MFI 

Diagnosis 

−

 Symptom Procedures 

P.13B-968

.

Q: Is an MFI system DTC P0513 output?

YES : Refer to GROUP 13A, MFI Diagnosis 

− Diagnostic 

Trouble Code Chart 

P.13A-753

 or GROUP 13B, MFI 

Diagnosis 

− Diagnostic Trouble Code Chart 

P.13B-796

.

NO :  Go to Step 2.

STEP 2. Check the immobilizer-ECU power supply circuit 
by backprobing.

(1) Do not disconnect immobilizer-ECU connector C-124.
(2) Turn the ignition switch to the "ON" position.

(3) Measure the voltage between terminal 1 and ground by 

backprobing.

• The voltage should measure approximately 12 volts 

(battery positive voltage).

Q: Is the measured voltage approximately 12 volts (battery 

positive voltage)?
YES : Go to Step 5.
NO :  Go to Step 3.

AC305412

AB

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

AC305231CQ

CONNECTOR: C-124

HARNESS SIDE

AC209365HR

CONNECTOR C-124 
(HARNESS SIDE)

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STEP 3. Check immobilizer-ECU connector C-124 and MFI 
relay connector B-17X for loose, corroded or damaged 
terminals, or terminals pushed back in the connector.

Q: Are immobilizer-ECU connector C-124 and MFI relay 

connector B-17X in good condition?
YES : Go to Step 4.
NO :  Repair or replace the component(s). Refer to GROUP 

00E, Harness Connector Inspection 

P.00E-2

. Confirm 

that scan tool MB991958 communicates normally.

AC305977

RELAY BOX SIDE

CONNECTOR: B-17X

AM

AC305231CQ

CONNECTOR: C-124

HARNESS SIDE