Mitsubishi Galant (2004+). Manual - part 305

SYMPTOM PROCEDURES

TSB Revision

SIMPLIFIED WIRING SYSTEM (SWS)

54B-411

INSPECTION PROCEDURE J-1: Fog Light: Fog lights do not illuminate when the fog light switch is 
turned on.

NOTE: This troubleshooting procedure requires the 
use of scan tool MB991958 and SWS monitor kit 
MB991813. For details on how to use the SWS mon-
itor, refer to "How to use SWS monitor 

P.54B-15

."

.

BATTERY

FOG
LIGHT
(RH)

FOG
LIGHT
(LH)

FRONT-ECU

RELAY
BOX

FOG LIGHT
RELAY

Fog Light Circuit

AC305977AC

CONNECTORS: A-05X, A-11X

A-11X

A-05X

SYMPTOM PROCEDURES

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SIMPLIFIED WIRING SYSTEM (SWS)

54B-412

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 illuminating at low beam.

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

nate the fog lights.

.

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

.

TROUBLESHOOTING HINTS

• Trouble in input signal system

• The wiring harness or connectors may have 

loose, corroded, or damaged terminals, or termi-
nals pushed back in the connector

• The fog light relay may be defective

• The front-ECU may be defective

• The ETACS-ECU may be defective

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

• MB991910: MUT-III Main Harness A

• MB991813: SWS Monitor Kit

• MB991806: SWS Monitor Cartridge

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

• MB991822: Probe Harness

STEP 1. Check the headlight (low-beam) operation.
Q: Do the headlights illuminate at low beam normally?

YES : Go to Step 2.
NO :  Refer to Inspection Procedure H-2 "The headlights 

(low-beam) do not illuminate normally 

P.54B-313

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SYMPTOM PROCEDURES

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SIMPLIFIED WIRING SYSTEM (SWS)

54B-413

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 MB991958, always turn the 
ignition switch to the "LOCK" (OFF) position before con-
necting or disconnecting scan tool MB991958. Connect 
special tool MB991910 before connecting special tool 
MB991812. Be sure to connect special tool MB991806 after 
turning on special tool MB991824.
(1) Connect the special tool. Refer to "How to connect SWS 

monitor 

P.54B-13

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(2) Operate scan tool MB991958 according to the procedure 

below to display "F.FOG."
a. Select "Interactive Diagnosis."
b. Select "System select."
c. Select "SWS."
d. Select "SWS MONITOR."
e. Select "Function Diag."
f. Select "LIGHTING."
g. Select "F.FOG."

(3) Check that normal conditions are displayed for the items 

described in the table below.

Q: Does the scan tool MB991958 display the items "IG SW 

(IG1)" and "F.FOG LIGHT" as normal condition?
Normal conditions are displayed for all the items : Go to 

Step 3.

Normal condition is not displayed for "IG SW (IG1)" : 

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

P.54B-490

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Normal condition is not displayed for "F.FOG LIGHT" : 

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

P.54B-493

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ITEM NO.

ITEM NAME

NORMAL CONDITION

ITEM 30

IG SW (IG1)

ON

ITEM 36

F.FOG LIGHT

ON

AC305411AB

MB991910

DATA LINK

CONNECTOR

MB991827

MB991824

MB991806

MB991812

AC302210

COLUMN SWITCH 
CONNECTOR

COLUMN SWITCH 
CONNECTOR AT 
HARNESS SIDE 

MB991812

AB

SYMPTOM PROCEDURES

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SIMPLIFIED WIRING SYSTEM (SWS)

54B-414

STEP 3. Check fog light relay connector A-05X for loose, 
corroded or damaged terminals, or terminals pushed back 
in the connector.

Q: Is fog light relay connector A-05X in good condition?

YES : Go to Step 4.
NO :  Repair or replace the damaged component(s). Refer 

to GROUP 00E, Harness Connector Inspection 

P.00E-2

. Verify that the fog lights illuminate normally.

STEP 4. Check the fog light relay.

Q: Is the fog light relay in good condition?

YES : Go to Step 5.
NO :  Replace the fog light relay. Verify that the fog lights 

illuminate normally.

AC305979 AB

CONNECTOR: A-05X

RELAY BOX SIDE

FRONT OF VEHICLE

BATTERY VOLTAGE TESTER 

CONNECTION

SPECIFIED 
CONDITION

Not applied

1 

− 4

Open circuit

• Connect terminal 2 

to the positive 
battery terminal

• Connect terminal 3 

to the negative 
battery terminal

1 

− 4

Less than 2 ohms

1

4

3

2

AC306645

2

1

3

4

FRONT OF 
VEHICLE

FOG LIGHT RELAY

AB

CONNECTOR: A-05X