Mitsubishi 380. Manual - part 95

SYMPTOM PROCEDURES

SIMPLIFIED WIRING SYSTEM (SWS)

54B-377

CIRCUIT OPERATION

The ETACS-ECU operates the dome lamp dimming 
function according to the input signals from the fol-
lowing switches:

• Ignition switch (IG1): OFF

• Key reminder switch: ON

• Door switches: OFF

• Driver's door lock actuator switch: LOCK or 

UNLOCK

.

TECHNICAL DESCRIPTION (COMMENT)

If the dome lamps do not dim normally, the input cir-
cuits from the switches described in "CIRCUIT 
OPERATION" or the ETACS-ECU may be defective.

.

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 ETACS-ECU may be defective

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 dome lamp.
If a door is opened while the dome lamp switch is at 
"door-linked" position, the dome lamp should illuminate.

Q: Does the dome lamp illuminate normally?

YES : Go to Step 2.
NO :  Refer to Inspection Procedure K-1 "The dome lamp 

do not illuminate and go out normally 

P.54B-359

."

STEP 2. Check the adjustment function.

Q: Has the dome lamp delay-off time been set to other than 

"0 second" by the adjustment function?
YES : Go to Step 3.
NO :  Set the dome lamp delay-off time to "0 second."

SYMPTOM PROCEDURES

SIMPLIFIED WIRING SYSTEM (SWS)

54B-378

STEP 3. Use diagnostic tool MB991958 to select "ECU 
COMM Check" on the SWS monitor display. 
Check the ETACS-ECU.

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

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

COMM Check" menu for the "ETACS ECU" menu.

Q: Is "OK" displayed for the "ETACS ECU" menu?

YES : Go to Step 4.
NO :  Refer to Inspection Procedure A-3 "Communication 

with the ETACS-ECU is not possible 

P.54B-74

."

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-379

STEP 4. Check the input signal by using "DATA LIST" 
menu of the SWS monitor.
Check the input signals from the following switches:

• Ignition switch: OFF

• Driver’s or front passenger’s door: open

(1) Operate diagnostic tool MB991958 according to the 

procedure below to display "ETACS ECU."
a. Select "Interactive Diagnosis."
b. Select "System select."
c. Select "SWS."
d. Select "SWS MONITOR."
e. Select "Data List."
f.

Select "ETACS ECU."

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

described in the table below.

Q: Does the diagnostic tool MB991958 display "IG SW 

(IG1)" as normal condition?
YES : Go to Step 5.
NO :  Refer to Inspection Procedure M-2 "ETACS-ECU 

does not receive any signal from the ignition switch 
(IG1) 

P.54B-408

."

ITEM NO.

ITEM NAME

NORMAL CONDITION

ITEM 30

IG SW (IG1)

OFF

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-380

STEP 5. Check the input signal (by using the pulse check 
mode of the monitor).
Check the input signals from the following switches:

• Key reminder switch

• Door switches

• Trunk lid latch assembly

(1) Operate diagnostic tool MB991958 according to the 

procedure below to display "Pulse check."
a. Select "Interactive Diagnosis."
b. Select "System select."
c. Select "SWS."
d. Select "Pulse Checking."

(2) Check if diagnostic tool MB991958 sounds or not.

Q: When the key reminder switch, any door switch, or the 

trunk lid is operated, does diagnostic tool MB991958 
sound?
Buzzer of diagnostic tool MB991958 sounds normally. : 

Replace the ETACS-ECU. Verify that the dome lamp 
dimming function works normally.

Diagnostic tool MB991958 does not sound when the 
ignition key is removed and reinserted : Refer to 

Inspection Procedure N-1 "ETACS-ECU does not 
receive a signal from the key reminder switch 

P.54B-432

."

Diagnostic tool MB991958 does not sound whenever a 
door switch is operated : Refer to Inspection Procedure 

N-3 "ETACS-ECU does not receive any signal from 
any of the door switches 

P.54B-440

."

When the trunk lid is opened and closed, diagnostic 
tool MB991958 does not sound. : Refer to Inspection 

Procedure N-7 "ETACS-ECU does not receive any 
signal from trunk lid latch assembly 

P.54B-469

."

ITEM NAME

CONDITION

key reminder switch

Remove and reinsert the ignition 
key

door switches

Open or close one of the doors

trunk lid latch assembly

Open or close the trunk lid

00DB076A

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827