Mitsubishi 380. Manual - part 77

SYMPTOM PROCEDURES

SIMPLIFIED WIRING SYSTEM (SWS)

54B-305

INSPECTION PROCEDURE H-9: Headlamp and Taillamp: Headlamp automatic shutoff function does 
not work normally.

NOTE: This troubleshooting procedure requires the 
use of Diagnostic Tool MB991958 and SWS monitor 
kit MB991813. For details on how to use the SWS 
monitor, refer to "How to connect SWS monitor 

P.54B-13

."

.

CIRCUIT OPERATION

The ETACS-ECU operates the headlamp automatic 
shutdown function according to the following signals:

• Ignition switch (IG1): OFF

• Driver's door switch: ON

• Taillamp switch: ON

• Headlamp switch: ON

The ETACS-ECU operates the headlamp automatic 
shutdown function under the following conditions:

• Ignition key: Other than "ON" position

• Driver's door: open

• Taillamps or headlamps: on

.

TECHNICAL DESCRIPTION (COMMENT)

If the function does not work normally, the input cir-
cuit system from the switches, the ETACS-ECU or 
the front-ECU may be defective (refer to "CIRCUIT 
OPERATION").

.

TROUBLESHOOTING HINTS

• Refer to circuit diagrams GROUP-

90

• Refer to configuration diagrams GROUP-

80

• 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

· 

DRIVER'S DOOR

 SWITCH

· IGNITION SWITCH (IG1)

· TAILLIGHT SWITCH

ETACS-

ECU

INPUT SIGNAL

Headlight Automatic Shutt-Down Function

SYMPTOM PROCEDURES

SIMPLIFIED WIRING SYSTEM (SWS)

54B-306

DIAGNOSIS

Required Special Tools:

• MB991223: Harness Set

• MB991958: Diagnostic 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: Test Probe Harness

STEP 1. Check the adjustment function.

Q: Has a setting other than "No auto-shutoff" been 

selected for the headlamp automatic shutdown 
function?
YES : Go to Step 2.
NO :  Set the headlamp automatic shutdown function to 

another setting other than "No auto-shutoff".

SYMPTOM PROCEDURES

SIMPLIFIED WIRING SYSTEM (SWS)

54B-307

STEP 2. Check the input signal by using "DATA LIST" 
menu of the SWS monitor.
Check the input signals from the following switches:

• Ignition switch: "ON" to "OFF"

• Lighting switch: "TAIL" or "HEAD"

CAUTION

To prevent damage to Diagnostic Tool MB991958, always 
turn the ignition switch to the "LOCK" (OFF) position 
before connecting or disconnecting Diagnostic Tool 
MB991958. Connect special tool MB991910 before con-
necting 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 Diagnostic Tool MB991958 according to the 

procedure below to display "H/L AUTO-CUT."
a. Select "Interactive Diagnosis."
b. Select "System select."
c. Select "SWS."
d. Select "SWS MONITOR."
e. Select "Function Diag."
f.

Select "LIGHTING."

g. Select "H/L AUTO-CUT."

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

described in the table below.

(5) When the driver's door is opened, check that normal 

conditions are displayed for the items described in the table 
below.

Q: Does the Diagnostic Tool MB991958 display the items 

"TAILLAMP SW", "IG SW IG1", "FRONT DOOR SW" and 
"H/L AUTO-CUT" as normal condition?
Normal conditions are displayed for all the items : 

Replace the front-ECU. Verify that the headlamp 
automatic shutdown function works normally.

Normal condition is not displayed for "TAILLAMP SW" : 

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

P.54B-420

."

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 

ITEM NO.

ITEM NAME

NORMAL CONDITION

ITEM 01

TAILLAMP SW

ON

ITEM 30

IG SW (IG1)

OFF

ITEM NO.

ITEM NAME

NORMAL CONDITION

ITEM 32

FRONT DOOR SW

ON

ITEM 35

H/L AUTO-CUT

ON

00DB076A

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

AC302210

COLUMN SWITCH 
CONNECTOR

COLUMN SWITCH 
CONNECTOR AT 
HARNESS SIDE 

MB991812

AB

SYMPTOM PROCEDURES

SIMPLIFIED WIRING SYSTEM (SWS)

54B-308

(IG1) 

P.54B-408

."

Normal condition is not displayed for "FRONT DOOR 
SW" : Refer to Inspection Procedure M-4 "ETACS-ECU 

does not receive any signal from the front door 
switches 

P.54B-413

."

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

Replace the front-ECU. Check that the headlamp 
automatic shutdown function works normally.

INSPECTION PROCEDURE H-10: Headlamp and Taillamp: Headlamp dimmer switch automatic 
resetting function does not work normally.

.

CIRCUIT OPERATION

The headlamp dimmer switch automatic resetting 
function is controlled by the front-ECU.

.

TECHNICAL DESCRIPTION (COMMENT)

If the headlamp dimmer switch automatic resetting 
function does not work normally, the front-ECU may 
be defective.

.

TROUBLESHOOTING HINT

• Refer to circuit diagrams GROUP-

90

• Refer to configuration diagrams GROUP-

80

The front-ECU may be defective

DIAGNOSIS

Replace the front-ECU.
Check that the headlamp dimmer switch automatic resetting 
function works normally.

· 

DIMMER

 SWITCH

· HEADLIGHT SWITCH

ETACS-

ECU

INPUT SIGNAL

Headlight (Dimmer/Passing) Input Signal