Mitsubishi Montero (2002-2004). Manual - part 345

SYMPTOM PROCEDURES

TSB Revision

SWS SYMPTOM PROCEDURES

54Bb-427

INSPECTION PROCEDURE L-1: Fog Light: Fog lights do not illuminate when the fog light switch is 
operated.

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

."

Fog Light Circuit

SYMPTOM PROCEDURES

TSB Revision

SWS SYMPTOM PROCEDURES

54Bb-428

.

CIRCUIT OPERATION

• The ETACS-ECU sends a fog light illumination 

request signal ("LIGHT ON" signal) to the front-
ECU when the fog light switch is turned on while 
the headlights are on.

• Then the front-ECU switches on its relay to illumi-

nate the fog lights.

.

TECHNICAL DESCRIPTION (COMMENT)
If the headlights illuminate normally, the fog light 
relay, the fog light switch, the front-ECU or the 
ETACS-ECU may be defective.

.

TROUBLESHOOTING HINTS

• The fog light relay may be defective

• The fog light switch may be defective

• The front-ECU may be defective

• The ETACS-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

• MB991502: Scan Tool (MUT-II) 

• MB991862: SWS monitor kit 

STEP 1. Verify the headlight operation.
Q: Do the headlights illuminate normally?

The lights illuminate normally at both high and low 
beams : Go to Step 2.
Headlights do not Illuminate at low beam : Refer to 

Inspection Procedure J-2 "Headlights (low-beam) do 
not illuminate normally 

P.54Bb-308

."

Headlights do not Illuminate at high beam : Refer to 

Inspection Procedure J-3 "Headlights (high-beam) do 
not illuminate normally 

P.54Bb-313

."

AC204183

CONNECTORS : A-07X, A-13X

A-13X

A-07X

AJ

AC204167

CONNECTORS : A-15, A-21, A-25

A-15

AQ

A-25(B)

A-21(B)

SYMPTOM PROCEDURES

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SWS SYMPTOM PROCEDURES

54Bb-429

STEP 2. Check the input signal by using "FUNCTION 
DIAG." menu of the SWS monitor.
Set each switch to the following condition before checking input 
signal from the fog light switch:

• Ignition switch: ON

• Fog light switch: ON

NOTE: Turn the ignition switch to the "ON" position in order to 
disable the headlight automatic shutdown function.

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) Operate scan tool MB991502 according to the procedure 

below to display "F.FOG LIGHT"

1. Select "SYSTEM SELECT."
2. Select "SWS."
3. Select "SWS MONITOR."
4. Select "FUNCTION DIAG."
5. Select "LIGHTING."
6. Select "F.FOG LIGHT."

(4) Check that normal conditions are displayed on the items 

described in the table below.

Q: Are normal conditions displayed on the "IG SW(IG1)" 

and "F.FOG LIGHT"?
YES : Go to Step 3.
NO : 

• Normal condition is not displayed on the "IG 

SW(IG1)": Refer to Inspection Procedure O-2 
"ETACS-ECU does not receive any signal from 
the ignition switch (IG1) 

P.54Bc-7

."

• Normal condition is not displayed on the "F.FOG 

LIGHT": Refer to Inspection Procedure O-3 
"ETACS-ECU does not receive any signal from 
the fog light switch 

P.54Bc-10

."

ITEM NO.

ITEM NAME

NORMAL 
CONDITION

ITEM 30

IG SW(IG1)

ON

ITEM 36

F.FOG LIGHT

ON

AC204222AB

16-pin

13-pin

MB991502

MB991862

SYMPTOM PROCEDURES

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SWS SYMPTOM PROCEDURES

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STEP 3. Check the fog light relay.

Q: Is the fog light relay in good condition?

YES : Go to Step 4.
NO :  Replace the fog light relay. Verify that the fog lights 

illuminate normally.

STEP 4. Check the battery power supply circuit to the fog 
light relay. Test at fog light relay connector A-13X.
(1) Disconnect fog light relay connector A-13X and measure at 

the voltage available at the relay box side of the connector.

(2) Measure the voltage between terminal 3 and ground, and 

also between terminal 4 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 7.
NO :  Go to Step 5.

BATTERY 
VOLTAGE

TESTER 
CONNECTION

SPECIFIED 
CONDITION

Not applied

4 

− 5

Open circuit

3 

− Battery (+) 

terminal,
1 

− Battery (-) 

terminal

4 

− 5

Less than 2 ohms

4

5

3

1

AC204764

1

5

4

3

2

RELAY SIDE

AB

FOG LIGHT RELAY

AC204183

CONNECTOR : A-13X

RELAY BOX SIDE

AF

2 1

5

4

3

A-13X

1

2

3

4

5

ACX01590AB

CONNECTOR A-13X
(RELAY BOX SIDE)