Mitsubishi Galant 9G. Manual — part 77

SYMPTOM PROCEDURES

TSB Revision

SIMPLIFIED WIRING SYSTEM (SWS)

54B-304

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-71

."

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

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

P.54B-86

."

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-305

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-484

."

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-362

."

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-306

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.

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)

SYMPTOM PROCEDURES

TSB Revision

SIMPLIFIED WIRING SYSTEM (SWS)

54B-307

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.

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

."

.

AC305977AH

CONNECTOR: A-11X

RELAY BOX SIDE

HEADLIGHT
RELAY: HIGH

HEADLIGHT
(LH)

HEADLIGHT
(RH)

· HEADLIGHT
AUTOMATIC
SHUTDOWN
· HEADLIGHT
SWITCH

INPUT SIGNAL

BATTERY

FRONT-ECU

RELAY
BOX

Headlight Relay (High-Beam) Circuit