Mitsubishi Montero (2002-2004). Manual - part 315

SYMPTOM PROCEDURES

TSB Revision

SWS SYMPTOM PROCEDURES

54Bb-307

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 5 and ground.

• The voltage should be approximately 12 volts (battery 

positive voltage).

Q: Is the measured voltage approximately 12 volts (battery 

positive voltage)?
YES : Replace the front-ECU. Verify that the taillights 

illuminate normally.

NO :  Go to Step 4.

STEP 4. 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 5.
NO :  Repair or replace the damaged component(s). Refer 

to GROUP 00E, Harness Connector Inspection 

P.00E-2

. Verify that the taillights illuminate normally.

AC204183

CONNECTOR : A-07X

AB

2 1

3

4

6

7

8

9

5

11 10

RELAY BOX SIDE

AC102043

1

2

3

4

5

6

7

8

9

10

11

AC

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

SYMPTOM PROCEDURES

TSB Revision

SWS SYMPTOM PROCEDURES

54Bb-308

STEP 5. Check the wiring harness between front-ECU 
connector A-07X (terminal 5) and the battery.
Q: Is the wiring harness between front-ECU connector A-

07X (terminal 5) 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. Verify that 
the taillights illuminate normally.

INSPECTION PROCEDURE J-2: Headlight and Taillight: Headlights (low-beam) do not illuminate.

NOTE: This troubleshooting procedure requires the 
use of scan tool MB991502 and SWS monitor kit 
MB991862. For details on how to use the SWS mon-
itor, refer to "How to use SWS monitor 

P.54Ba-8

."

AC204183

CONNECTOR : A-07X

AB

2 1

3

4

6

7

8

9

5

11 10

RELAY BOX SIDE

Headlight Relay (Low-beam) Circuit

SYMPTOM PROCEDURES

TSB Revision

SWS SYMPTOM PROCEDURES

54Bb-309

.

CIRCUIT OPERATION

• When the lighting switch is set to "HEAD" posi-

tion, the "HEAD" signal is sent through the col-
umn-ECU (incorporated in the column switch) to 
the front-ECU. If the front-ECU receives the 
"HEAD" signal through the column-ECU, the 
front-ECU turns on the headlight relay (incorpo-
rated in the front-ECU), thus causing the head-
lights to illuminate. The headlights always 
illuminate at low-beam by the headlight dimmer 
switch automatic resetting function.

• If the SWS communication line is defective, the 

front-ECU operates the headlights by using the 
other communication lines (headlight backup cir-
cuit) instead of that line.

.

TECHNICAL DESCRIPTION (COMMENT)
If the headlights (low-beam) do not illuminate nor-
mally, the column switch or the front-ECU may be 
defective. 

.

TROUBLESHOOTING HINTS

• The column switch (turn-signal light and lighting 

switch) 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

AC204183

CONNECTOR : A-07X

AG

SYMPTOM PROCEDURES

TSB Revision

SWS SYMPTOM PROCEDURES

54Bb-310

DIAGNOSIS

Required Special Tools:

• MB991223: Harness Set

• MB991502: Scan Tool (MUT-II) 

• MB991862: SWS monitor kit 

STEP 1. Use scan tool MB991502 to select "ECU COMM 
CHK" on the SWS monitor display.
Check the following ECUs:

• Column-ECU

• Front-ECU

CAUTION

To prevent damage to scan tool MB991502, always turn the 
ignition switch to the "LOCK" (OFF) position before con-
necting or disconnecting scan tool MB991502.
(1) Connect scan tool MB991502 to the data link connector 

(16-pin).

(2) Connect SWS monitor kit MB991862 to the data link 

connector (13-pin).

(3) Turn the ignition switch to the "LOCK" (OFF) position.
(4) Operate scan tool MB991502 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."

(5) Scan tool MB991502 should show "OK" on the "ECU 

COMM CHK" menus for both the "COLUMN ECU" and the 
"FRONT ECU" menus.

Q: Is "OK" displayed on both the "COLUMN ECU" and 

"FRONT ECU" menus?
"OK" are displayed for all the items : Go to Step 2.
"NG" is displayed on the "COLUMN ECU" menu : Refer 

to Inspection Procedure A-2 "Communication with 
column switch (column-ECU) is not possible 

P.54Bb-

16

."

"NG" is displayed on the "FRONT ECU" menu : Refer to 

Inspection procedure A-4 "Communication with front-
ECU is not possible 

P.54Bb-32

."

AC204222AB

16-pin

13-pin

MB991502

MB991862