Mitsubishi Galant (2004+). Manual - part 282

SYMPTOM PROCEDURES

TSB Revision

SIMPLIFIED WIRING SYSTEM (SWS)

54B-319

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

SYMPTOM PROCEDURES

TSB Revision

SIMPLIFIED WIRING SYSTEM (SWS)

54B-320

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

Check the following ECUs:

• Column switch (column-ECU)

• Front-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. 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

."

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

below to display "ECU COMM Check."
a. Select "Interactive Diagnosis."
b. Select "System select."
c. Select "SWS."
d. Select "SWS MONITOR."
e. Select "ECU COMM Check."

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

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

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

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

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

P.54B-72

."

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

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

P.54B-87

."

AC305411AB

MB991910

DATA LINK

CONNECTOR

MB991827

MB991824

MB991806

MB991812

AC302210

COLUMN SWITCH 
CONNECTOR

COLUMN SWITCH 
CONNECTOR AT 
HARNESS SIDE 

MB991812

AB

SYMPTOM PROCEDURES

TSB Revision

SIMPLIFIED WIRING SYSTEM (SWS)

54B-321

STEP 2. Check the input signal by using "FUNCTION 
DIAG." menu of the SWS monitor.

Check the input signals from the following switches:

• Ignition switch: ON

• Lighting switch: HEAD

• Dimmer switch: ON

(1) Operate scan tool MB991958 according to the procedure 

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

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

described in the table below.

Q: Does the scan tool MB991958 display the items 

"HEADLIGHT SW", "DIMMER SW", "H/L AUTO-CUT" 
and "FRONT ECU ACK" as normal condition?
Normal conditions are displayed for all the items : 

Replace the front-ECU. Verify that the headlights 
(high-beam) illuminate normally.

Normal condition is not displayed for "HEADLIGHT SW" 
: 

Refer to Inspection Procedure M-5 "ETACS-ECU 
does not receive any signal from the headlight switch 

P.54B-505

."

Normal condition is not displayed for "DIMMER SW" : 

Refer to Inspection Procedure M-5 "ETACS-ECU 
does not receive any signal from the dimmer switch 

P.54B-505

."

Normal condition is not displayed for "H/L AUTO-CUT" : 

Refer to Inspection Procedure H-9 "Headlight 
automatic shutoff function does not work normally 

P.54B-373

."

Normal condition is not displayed for "FRONT ECU 
ACK" : Replace the front-ECU. Verify that the headlights 

(high-beam) illuminate normally.

ITEM NO.

ITEM NAME

NORMAL CONDITION

ITEM 00

HEADLIGHT SW

ON

ITEM 02

DIMMER SW

OFF (should turn "ON" 
momentarily when the 
dimmer switch is operated)

ITEM 35

H/L AUTO-CUT

OFF

ITEM 70

FRONT ECU ACK

HI-BEAM ACK

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-322

INSPECTION PROCEDURE H-4: Headlight and Taillight: When the passing switch is turned "ON," the 
headlights (low-beam or high-beam) do not illuminate.

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

."

.

TECHNICAL DESCRIPTION (COMMENT)
If both of the headlights (low-beam and high-beam) 
do not illuminate, the input circuit from the passing 
switch or the front-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 front-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 headlights.
Q: Do the headlights (low-beam and high-beam) illuminate 

normally?
The headlights illuminate normally. : Go to Step 2.
Headlights (low-beam) do not illuminate normally : 

Refer to Inspection Procedure H-2 "The headlights 
(low-beam) do not illuminate normally 

P.54B-313

.

Headlights (high-beam) do not illuminate normally : 

Refer to Inspection Procedure H-3 "The headlights 
(high-beam) do not illuminate normally 

P.54B-318

.