Mitsubishi Montero (2004+). Manual - part 698

SYMPTOM PROCEDURES

TSB Revision

SIMPLIFIED WIRING SYSTEM (SWS)

54B-49

Front-ECU Power Supply and SWS Communication Circuit

SYMPTOM PROCEDURES

TSB Revision

SIMPLIFIED WIRING SYSTEM (SWS)

54B-50

.

CIRCUIT OPERATION

• The power supply to the front-ECU is provided by 

the battery and the ignition switch (IG2).

•  If the power supply system from the battery is 

defective, the system operates by the power sup-
ply from the ignition switch (IG2).

.

TECHNICAL DESCRIPTION (COMMENT)
It is suspected that the power supply circuit to the 
front-ECU is defective, or the wiring harness 
between the SWS monitor kit and the front-ECU or 
their connector(s) is damaged. If the battery power 
supply circuit to the ECU (terminal 7 of the 
front-ECU) is damaged, also check the power supply 
circuit from the ignition switch (IG2) (terminal 30 of 
the front-ECU), and repair if necessary.

.

TROUBLESHOOTING HINTS

• The ETACS-ECU may be defective

• The front-ECU may be defective

• 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 B

• MB991813: SWS Monitor Kit

• MB991806: SWS Monitor Cartridge

• MB991812: SWS Monitor Harness (For Column-ECU)

• MB991822: Probe Harness

AC204183

CONNECTORS : A-07X, A-08X

A-08X

A-07X

AI

AC204170

CONNECTORS: D-02, D-28

BI

D-28

D-02

AC204174

CONNECTOR : D-224

D-224(B)

AG

SYMPTOM PROCEDURES

TSB Revision

SIMPLIFIED WIRING SYSTEM (SWS)

54B-51

STEP 1. Use scan tool MB991958 to select "ECU COMM 
CHK" on the SWS monitor display.
Check the ETACS-ECU.

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 the special tool. Refer to "How to connect SWS 

monitor 

P.54B-7

.

(2) Turn the ignition switch to the "LOCK" (OFF) position.
(3) Operate scan tool MB991958 according to the procedure 

below to display "ECU COMM CHK."

1. Select "SYSTEM SELECT."
2. Select "SWS."
3. Select "SWS MONITOR."
4. Select "ECU COMM CHK."

(4) Scan tool MB991958 should show "OK" on the "ECU 

COMM CHK" menu for the "ETACS ECU" menu.

Q: Is "OK" displayed on the "ETACS ECU" menu?

YES : Go to Step 2.
NO :  Refer to Inspection Procedure A-3 "Communication 

with ETACS-ECU is not possible 

P.54B-42

."

STEP 2. Check the front-ECU connector A-07X for loose, 
corroded or damaged terminals, or terminals pushed back 
in the connector. 

Q: Is the front-ECU connector A-07X in good condition?

YES : Go to Step 3.
NO :  Repair or replace the damaged component(s). Refer 

to GROUP 00E, Harness Connector Inspection 

P.00E-2

. The system should communicate with the 

front-ECU normally.

AC309091

MB991911

MB991827

MB991824 

AB

MB991806

MB991862

DATA LINK
CONNECTOR 
(16-PIN)

DATA LINK
CONNECTOR 
(13-PIN)

AC204183

CONNECTOR : A-07X

AB

2 1

3

4

6

7

8

9

5

11 10

RELAY BOX SIDE

SYMPTOM PROCEDURES

TSB Revision

SIMPLIFIED WIRING SYSTEM (SWS)

54B-52

STEP 3. Check the battery power supply circuit to the 
front-ECU. Test at front-ECU connector A-07X.
(1) Disconnect front-ECU connector A-07X and measure the 

voltage available at the relay box side of the connector.

(2) Measure the voltage between terminal 7 and ground.

• The voltage should be 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 4.

STEP 4. Check the wiring harness between front-ECU 
connector A-07X (terminal 7) and the battery.

Q: Is the wiring harness between front-ECU connector 

A-07X (terminal 7) and the battery in good condition?
YES : No action is necessary and testing is complete.
NO :  The wiring harness may be damaged or the 

connector(s) may have loose, corroded or damaged 
terminals, or terminals pushed back in the connector. 
Repair the wiring harness as necessary. The system 
should communicate with the front-ECU normally. 

STEP 5. Check the front-ECU connector A-08X for loose, 
corroded or damaged terminals, or terminals pushed back 
in the connector.

Q: Is front-ECU connector A-08X in good condition?

YES : Go to Step 6.
NO :  Repair or replace the damaged component(s). Refer 

to GROUP 00E, Harness Connector Inspection 

P.00E-2

. The system should communicate with the 

front-ECU normally.

AC204183

CONNECTOR : A-07X

AB

2 1

3

4

6

7

8

9

5

11 10

RELAY BOX SIDE

1

2

3

4

5

7

9

10

6

8

11

ACX01287AB

CONNECTOR A-07X
(RELAY BOX SIDE)

AC204183

CONNECTOR : A-07X

AB

2 1

3

4

6

7

8

9

5

11 10

RELAY BOX SIDE

AC204183

CONNECTOR : A-08X

AC

22

23

21

26 25

27

28

31 30 29

24

RELAY BOX SIDE

A-08X