Mitsubishi Montero (2004+). Manual — part 512

IGNITION SWITCH

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CHASSIS ELECTRICAL

54A-17

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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 set.

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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

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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 B

AC204171BI

CONNECTORS: D-116, D-134

D-134(GR)

D-116

AC204176

CONNECTOR: E-111

AK

IGNITION SWITCH

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CHASSIS ELECTRICAL

54A-18

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

−

Symptom Procedures

P.13A-834

.

Q: Is an MFI system DTC P0513 set?

YES : Go to Step 2.
NO : Refer to GROUP 13A, MFI Diagnosis

− Diagnostic

Trouble Code Procedures

P.13A-672

.

AC306409AF

MB991911

MB991824

MB991827

IGNITION SWITCH

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CHASSIS ELECTRICAL

54A-19

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

(1) Do not disconnect immobilizer-ECU connector D-121.
(2) Turn the ignition switch to the "ON" position.

(3) Measure the voltage between terminal 7 and ground by

backprobing.

Q: Is battery voltage (approximately 12 volts) present?

YES : Go to Step 5.
NO : Go to Step 3.

STEP 3. Check immobilizer-ECU connector D-121 and MFI
relay connector B-22X for loose, corroded or damaged
terminals, or terminals pushed back in the connector.

Q: Are immobilizer-ECU connector D-121 and MFI relay

connector B-22X damaged?
YES : Repair or replace them. Refer to GROUP 00E,

Harness Connector Inspection

P.00E-2

. Confirm that

scan tool MB991958 communicates normally.

NO : Go to Step 4.

AC204170

CONNECTOR : D-121

CV

HARNESS SIDE

2

3

8 7

9

10

1
6

5

12

4

11

AC204738 EB

HARNESS SIDE: D-121

4

3

2
7 8 9 10 11

5

12

1

6

AC204745

CONNECTOR : B-22X

AB

1
3 4

2

AC204170

CONNECTOR : D-121

CV

HARNESS SIDE

2

3

8 7

9

10

1
6

5

12

4

11

IGNITION SWITCH

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CHASSIS ELECTRICAL

54A-20

STEP 4. Check the harness wires between
immobilizer-ECU connector D-121 (terminal 7) and MFI
relay connector B-22X (terminal 1).

NOTE: Also check intermediate connector E-111 and joint con-
nector D-116,check the wires. If intermediate connector E-111
and joint connector D-116 are damaged, repair or replace
them. Refer to GROUP 00E, Harness Connector Inspection

P.00E-2

.

Q: Are the harness wires between immobilizer-ECU

connector D-121 (terminal 7) and MFI relay connector
B-22X (terminal 1) damaged?
YES : Replace them. Confirm that scan tool MB991958

communicates normally.

NO : There is no action to be taken.

AC204745

CONNECTOR : B-22X

AB

1
3 4

2

AC204170

CONNECTOR : D-121

CV

HARNESS SIDE

2

3

8 7

9

10

1
6

5

12

4

11

AC204171

CONNECTOR : D-116

AD

9 10

8

6 7

31 32

30

29

18 19 20 21

5

4

2

1

3

27

26

24

23

25

12 13 14 15 16 17

28

11
22
33

AC204176

CONNECTOR : E-111

BF

15

4

14

37

36

26 27

12

11

35

34

23 24

3

13

25

9

2

8

32

20 21

6

5

17

29

30

18

1

7

19

31

10

22

33

16

28

38