Mitsubishi Galant (2004+). Manual - part 281

 

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Mitsubishi Galant (2004+). Manual - part 281

 

 

SYMPTOM PROCEDURES

TSB Revision

SIMPLIFIED WIRING SYSTEM (SWS)

54B-315

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-316

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

(1) Operate scan tool MB991958 according to the procedure 

below to display "HEADLIGHT LO."
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 LO."

(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", "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 "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 "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 

(low-beam) illuminate normally.

ITEM NO.

ITEM NAME

NORMAL 
CONDITION

ITEM 00

HEADLIGHT 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

SYMPTOM PROCEDURES

TSB Revision

SIMPLIFIED WIRING SYSTEM (SWS)

54B-317

STEP 3. Check front-ECU connector A-11X for loose, 
corroded or damaged terminals, or terminals pushed back 
in the connector.

Q: Is front-ECU connector A-11X 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 headlights (low-beam) 

illuminate normally.

STEP 4. Check the battery power supply circuit to the 
front-ECU. Measure the voltage at front-ECU connector 
A-11X.

(1) Disconnect front-ECU connector A-11X and measure the 

voltage available at the relay box side of the connector.

(2) Measure the voltage between terminal numbers 8 and 

ground, and also between terminal 9 and ground.

• The voltage should measure approximately 12 volts 

(battery positive voltage).

Q: Is the measured voltage approximately 12 volts (battery 

positive voltage)?
YES : 
Replace the front-ECU. Verify that the headlights 

(low-beam) illuminate normally.

NO :  Go to Step 5.

STEP 5. Check the wiring harness between front-ECU 
connector A-11X (terminals 8 and 9) and the battery.

Q: Is the wiring harness between front-ECU connector 

A-11X (terminals 8 and 9) and the battery in good 
condition?
YES : 
No action is necessary and testing is complete.
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 headlights (low-beam) illuminate normally.

AC305977AH

CONNECTOR: A-11X

RELAY BOX SIDE 

AC305977AH

CONNECTOR: A-11X

RELAY BOX SIDE 

AC209364CT

5

11

9

10

8 7 6

2

4 3

1

CONNECTOR A-11X
(RELAY BOX SIDE)

AC305977AH

CONNECTOR: A-11X

RELAY BOX SIDE 

SYMPTOM PROCEDURES

TSB Revision

SIMPLIFIED WIRING SYSTEM (SWS)

54B-318

INSPECTION PROCEDURE H-3: Headlight and Taillight: The headlights (high-beam) 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

."

.

CIRCUIT OPERATION
When the dimmer switch is turned on, the column 
switch sends a signal to the front-ECU. Then the 
front-ECU switches the headlights from low-beam to 
high beam or vice versa.

.

TECHNICAL DESCRIPTION (COMMENT)
If the headlights (high beam) do not illuminate nor-
mally, 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

HEADLIGHT
RELAY: HIGH

HEADLIGHT
(LH)

HEADLIGHT
(RH)

· HEADLIGHT
  AUTOMATIC
  SHUTDOWN
· HEADLIGHT
  SWITCH

INPUT SIGNAL

BATTERY

FRONT-ECU

RELAY 
BOX

Headlight Relay (High-Beam) Circuit

 

 

 

 

 

 

 

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