Mitsubishi Galant (2004+). Manual — part 279

SYMPTOM PROCEDURES

TSB Revision

SIMPLIFIED WIRING SYSTEM (SWS)

54B-307

INSPECTION PROCEDURE H-1: Headlight and Taillight: The taillights do not illuminate normally.

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

."

.

TAILLIGHT
RELAY

· FRONT
COMBINATION
LIGHT (LH)
· FRONT SIDE
MARKER
LIGHT (LH)
· LICENSE PLATE
LIGHT
· REAR
COMBINATION
LIGHT (LH)

· FRONT
COMBINATION
LIGHT (RH)
· FRONT SIDE
MARKER
LIGHT (RH)
· REAR
COMBINATION
LIGHT (RH)

· HEADLIGHT
AUTOMATIC
SHUTDOWN
·TAILLIGHT
SWITCH

INPUT SIGNAL

BATTERY

FRONT-ECU

RELAY
BOX

Taillight Relay Circuit

AC305977AE

CONNECTOR: A-11X

SYMPTOM PROCEDURES

TSB Revision

SIMPLIFIED WIRING SYSTEM (SWS)

54B-308

CIRCUIT OPERATION
When the lighting switch is set to "TAIL" position, the
"TAIL" signal is sent through the column-ECU (incor-
porated in the column switch) to the front-ECU. If the
front-ECU receives the "TAIL" signal through the col-
umn-ECU, the front-ECU turns on the taillight relay
(incorporated in the front-ECU), thus causing the tail-
lights to illuminate.

.

TECHNICAL DESCRIPTION (COMMENT)
If the taillights do not illuminate normally, the column
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

SYMPTOM PROCEDURES

TSB Revision

SIMPLIFIED WIRING SYSTEM (SWS)

54B-309

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" menu?
"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-310

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: TAIL

NOTE: Turn the ignition switch to the "ON" position in order to
disable the headlight automatic shutdown function.
(1) Operate scan tool MB991958 according to the procedure

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

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

described in the table below.

Q: Does the scan tool MB991958 display the items

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

Step 3.

Normal condition is not displayed for "TAILLIGHT SW" :

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

illuminate normally.

ITEM NO.

ITEM NAME

NORMAL CONDITION

ITEM 01

TAILLIGHT SW

ON

ITEM 35

H/L AUTO-CUT

OFF

ITEM 70

FRONT ECU ACK

NORMAL ACK

AC305411AB

MB991910

DATA LINK

CONNECTOR

MB991827

MB991824

MB991806

MB991812

AC302210

COLUMN SWITCH
CONNECTOR

COLUMN SWITCH
CONNECTOR AT
HARNESS SIDE

MB991812

AB