Mitsubishi Montero (2002-2004). Manual - part 478

SIDE STEP LIGHT

TSB Revision

CHASSIS ELECTRICAL

54A-83

.

TECHNICAL DESCRIPTION (COMMENT) 
If all of the side step light do not illuminate the side 
step light-ECU may be defective.

.

TROUBLESHOOTING HINTS

• The side step light-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 Tool:

• MB991223: Harness Set

 STEP 1. Check the battery power supply circuit to the side 
step light-ECU. Test at side step light-ECU connector D-
137.
(1) Disconnect side step light-ECU connector D-137 and 

measure the voltage available at the harness side of the 
connector.

(2) Measure the voltage between terminal numbers 1 and 

ground.

• 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 4.
NO :  Go to Step 2.

AC204173

CONNECTORS : D-209, 221               

AL

D-209

D-221

AC204170

CONNECTOR : D-137

HARNESS SIDE

D-137(GR)

D-137(GR)

AR

1

2

8 7

4

5

10

11

12

6

9

3

AC204599

1

2

8 7

4

5

10

11

12

6

9

3

CONNECTOR D-137
(HARNESS SIDE)

AB

SIDE STEP LIGHT

TSB Revision

CHASSIS ELECTRICAL

54A-84

 STEP 2. Check side step light-ECU connector D-137 for 
loose, corroded or damaged terminals, or terminals 
pushed back in the connector.
Q:  Is side step light-ECU connector D-137 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

. Verify that the side step light illuminate 

normally.

AC204170

CONNECTOR : D-137

HARNESS SIDE

D-137(GR)

D-137(GR)

AR

1

2

8 7

4

5

10

11

12

6

9

3

SIDE STEP LIGHT

TSB Revision

CHASSIS ELECTRICAL

54A-85

 STEP 3. Check the wiring harness between side step light-
ECU connector D-137 (terminal 1) and the fusible link (1).

ACX02274

FUSIBLE LINK (1)

AE

BATTERY

AC204188

CONNECTORS : D-28, D-137

D-137(GR)

AO

HARNESS SIDE

D-137(GR)

D-28

D-28

1

2

8 7

4

5

10

11

12

6

9

3

2 3

27

32

28

33

16

15

4 5

19

18

29

17

34

7 8

35

22

21

9 10

30

36

31

37

25

24

23

6

20

1

14

26

11

13

12

38

SIDE STEP LIGHT

TSB Revision

CHASSIS ELECTRICAL

54A-86

NOTE: Also check intermediate connector D-28, junction block 
connectors D-209 and D-221 for loose, corroded, or damaged 
terminals, or terminals pushed back in the connector. If inter-
mediate connector D-28, junction block connectors D-209 or D-
221 is damaged, repair or replace the connector as described 
in GROUP 00E, Harness Connector Inspection 

P.00E-2

.

Q:  Is the wiring harness between side step light-ECU 

connector D-137 (terminal 1) and the fusible link (1) in 
good condition?
YES : Replace the side step light-ECU. Verify that the side 

step light illuminate normally.

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 side step light illuminate normally.

 STEP 4. Check the ignition switch (IG1) circuit to the side 
step light-ECU. Test at side step light-ECU connector D-
137.
(1) Disconnect side step light-ECU connector D-137 and 

measure the voltage available at the harness side of the 
connector.

(2) Turn the ignition switch to the "ON" position.

(3) Measure the voltage between terminal numbers 2 and 

ground.

• 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 7.
NO :  Go to Step 5.

AC204191

CONNECTORS : D-209, D-221

D-209

AF

HARNESS SIDE

HARNESS SIDE

D-221

D-209

D-221

3

1

4

6 5

7

8

2

1

2

6

7

9

3

4

11

12

10

5

13

8

AC204170

CONNECTOR : D-137

HARNESS SIDE

D-137(GR)

D-137(GR)

AR

1

2

8 7

4

5

10

11

12

6

9

3

AC204600

1

2

8 7

4

5

10

11

12

6

9

3

CONNECTOR D-137
(HARNESS SIDE)

AB