Mitsubishi Grandis. Manual - part 204

SYMPTOM PROCEDURES

SMART WIRING SYSTEM (SWS) USING SWS MONITOR

54C-278

Inspection Procedure M-3: The high-beam headlamps do not illuminate normally.

CAUTION

Whenever the ECU is replaced, ensure that the 
input and output signal circuits are normal.

COMMENTS ON TROUBLE SYMPTOM

If the high-beam headlamps do not illuminate, the 
dimmer switch input circuit or the front-ECU may be 
defective.

POSSIBLE CAUSES

• Malfunction of the column switch

• Malfunction of the front-ECU

• Damaged harness wires and connectors

DIAGNOSIS PROCEDURE

Step 1. ECU check by using the SWS monitor.

Check that the power supply and earth lines to the 
column switch (column-ECU) and the front-ECU and 
the SWS communication lines are normal.

• Ignition switch: OFF

ECUS TO BE CHECKED

• COLUMN ECU

• FRONT ECU

OK: "OK" are displayed for all the items

Q: Are the check result normal?

"OK" are displayed for all the items : 

Go to Step 2.

"NG" is displayed on the "COLUMN ECU" menu. : 

Refer to Inspection Procedure A-2 
"Communication with the column switch 
(column-ECU) is not possible 

P.54C-56

."

"NG" is displayed on the "FRONT ECU" menu. : 

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

P.54C-70

."

FUSIBLE LINK 

26

Wire colour code
B : Black     LG : Light green     G : Green     L : Blue
W : White     Y : Yellow     SB : Sky blue     BR : Brown
O : Orange     GR : Gray     R : Red     P : Pink     V : Violet

FRONT-ECU

HEADLAMP
RELAY: HI

RELAY
BOX

INPUT SIGNAL

· HEADLAMP AUTOMATIC
  SHUTDOWN
· HEADLAMP SWITCH

HEADLAMP (HI: LH)

HEADLAMP (HI: RH)

Headlamp Relay (High-Beam) Circuit

SYMPTOM PROCEDURES

SMART WIRING SYSTEM (SWS) USING SWS MONITOR

54C-279

Step 2. Function diagnosis by using the SWS 
monitor.

Check the SWS communication signal, which are 
related to the high-beam headlamps.

<Selected item> LIGHTING - HEADLAMP HI

• Ignition switch: ON

• Lighting switch: HEAD

• Dimmer switch: from OFF to ON, and then to 

OFF again

OK: Normal conditions are displayed for all 
the items

Q: Are the check result normal?

Normal conditions are displayed for all the items. : 

Go to Step 3.

Normal condition is not displayed for item Nos.00, 
02 or 03. : 

Refer to inspection procedure Q-6 "The 

column switch (lighting and turn-signal lamp 
and headlamp washer switch) signal is not 
received 

P.54C-478

."

Normal condition is not displayed for item No.30. : 

Refer to inspection procedure Q-2 "The 
ignition switch (IG1) signal is not received 

P.54C-460

."

Normal condition is not displayed for item No.35. : 

Refer to Inspection Procedure M-5 "The 
headlamp automatic-shutdown function 
does not work normally 

P.54C-280

."

Normal condition is not displayed for item No.70. : 

Replace the front-ECU.

Step 3. Retest the system.

Check that the high-beam headlamps illuminate 
normally.

Q: Is the check result normal?

YES : 

The trouble can be an intermittent 

malfunction (Refer to GROUP 00 

− How to 

Cope with Intermittent Malfunction 

P.00-5

).

NO : 

Replace the front-ECU.

Inspection Procedure M-4: The high-beam and low-beam headlamps do not illuminate when the 
passing switch is operated.

CAUTION

Whenever the ECU is replaced, ensure that the 
input and output signal circuits are normal.

COMMENTS ON TROUBLE SYMPTOM

If the low-beam and high-beam headlamps are 
normal, the passing switch input signal circuit or the 
front-ECU may be defective.

POSSIBLE CAUSES

• Malfunction of the column switch

• Malfunction of the front-ECU

• Damaged harness wires and connectors

DIAGNOSIS PROCEDURE

Step 1. Check the operation of the headlamps.

Check that the low-beam and high-beam headlamps 
illuminate normally.

Q: Is the check result normal?

YES : 

Go to Step 2.

NO : 

Repair the headlamps. Refer to trouble 
symptom chart 

P.54C-44

.

Item No. Item name

Normal condition

Item 00

HEADLAMP 
SW

ON

Item 02

DIMMER SW

from OFF to ON, and 
then to OFF again ("ON" 
should be displayed 
when the dimmer switch 
is operated)

Item 03

PASSING SW OFF

Item 30

IG SW(IG1)

ON

Item 35

HD 
AUTO-CUT

OFF

Item 70

FRONT ECU 
ACK

NORMAL ACK

SYMPTOM PROCEDURES

SMART WIRING SYSTEM (SWS) USING SWS MONITOR

54C-280

Step 2. SWS monitor data list.

Check the ETACS-ECU signals which are related to 
the headlamps.

<Selected item> COLUMN ECU

• Passing lamp switch: ON

OK: Normal condition is displayed.

Q: Is the check result normal?

YES : 

Go to Step 3.

NO : 

Refer to inspection procedure Q-6 "The 
column switch (lighting and turn-signal lamp 
and headlamp washer switch) signal is not 
received 

P.54C-478

."

Step 3. Retest the system.

When the passing switch is turned on, check if the 
headlamps illuminate normally.

Q: Is the check result normal?

YES : 

The trouble can be an intermittent 

malfunction (Refer to GROUP 00 

− How to 

Cope with Intermittent Malfunction 

P.00-5

).

NO : 

Replace the front-ECU.

Inspection Procedure M-5: The headlamp automatic-shutdown function does not work normally.

CAUTION

Whenever the ECU is replaced, ensure that the 
input and output signal circuits are normal.

COMMENTS ON TROUBLE SYMPTOM

The ETACS-ECU operates this function in 
accordance with the input signals below.

• Ignition switch (IG1)

• Driver's door switch

• Tail lamp switch

• Headlamp switch

If this function does not work normally, these input 
signal circuit(s), the front-ECU or the ETACS-ECU 
may be defective. On vehicles with keyless entry 
system, note that this function can be 
disabled/enabled by the customize function (default 
setting; enabled).

POSSIBLE CAUSES

• Malfunction of the driver's door switch

• Malfunction of the front-ECU

• Malfunction of the column switch

• Malfunction of the ETACS-ECU

• Damaged harness wires and connectors

Item No.

Item name

Normal 
condition

Item 03

PASSING SW

ON

ETACS-ECU

INPUT SIGNAL

· DRIVER'S DOOR SWITCH

· TAIL LAMP SWITCH

· IGNITION SWITCH (IG1)

· HEADLAMP SWITCH

Headlamp Automatic Shutdown Function

SYMPTOM PROCEDURES

SMART WIRING SYSTEM (SWS) USING SWS MONITOR

54C-281

DIAGNOSIS PROCEDURE

Step 1. Check the SWS monitor Customize 
function function.

Check that "H/L AUTO CUT" is set to "W.FUNCTION 
(A)" or "W.FUNCTION (D)" by using the adjustment 
function.

Q: Is the check result normal?

YES : 

Go to Step 2.

NO : 

Set "H/L AUTO CUT" to "W.FUNCTION (A)" 
or "W.FUNCTION (D)" by using the 
adjustment function. (Refer to 

P.54C-574

).

Step 2. ECU check by using the SWS monitor.

Check that the power supply and earth lines to the 
column switch (column-ECU), the ETACS-ECU and 
the front-ECU and the SWS communication lines are 
normal.

• Ignition switch: OFF

ECUS TO BE CHECKED

• COLUMN ECU

• ETACS ECU

• FRONT ECU

OK: "OK" are displayed for all the items

Q: Are the check result normal?

"OK" are displayed for all the items : 

Go to Step 3.

"NG" is displayed on the "COLUMN ECU" menu. : 

Refer to Inspection Procedure A-2 
"Communication with the column switch 
(column-ECU) is not possible 

P.54C-56

."

"NG" is displayed on the "ETACS ECU" menu. : 

Refer to Inspection Procedure A-3 
"Communication with the ETACS-ECU is 
not possible 

P.54C-63

."

"NG" is displayed on the "FRONT ECU" menu. : 

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

P.54C-70

."

Step 3. SWS monitor data list.

Check the SWS communication signal, which are 
related to the headlamp automatic-shutdown 
function.

<Selected item> LIGHTING - HD AUTO-CUT

• Ignition switch: from ON to OFF

• Lighting switch: "TAIL" or "HEAD"

Check that the MUT-III displays normal condition 
when the condition above is changed to the condition 
below.

• Driver's door: open

OK: Normal conditions are displayed for all 
the items

Q: Are the check result normal?

Normal conditions are displayed for all the items : 

Go to Step 4.

Normal condition is not displayed for item Nos.00 
or 01. : 

Refer to inspection procedure Q-6 "The 

column switch (lighting and turn-signal lamp 
switch) signal is not received 

P.54C-478

."

Normal condition is not displayed for item No.30. : 

Refer to inspection procedure Q-2 "The 
ignition switch (IG1) signal is not received 

P.54C-460

."

Normal condition is not displayed for item No.32. : 

Refer to inspection procedure Q-5 "The 
driver's door switch signal is not received 

P.54C-474

 <LH drive vehicles> or 

P.54C-476

 <RH drive vehicles>."

Normal condition is not displayed for item Nos.35 
or 70. : 

Replace the front-ECU.

Item No.

Item name

Normal 
condition

Item 00

HEADLAMP SW ON when the 

lighting switch is 
at HEAD

Item 01

TAIL LAMP SW

ON when the 
lighting switch is 
at TAIL

Item 30

IG SW(IG1)

from ON to OFF

Item 70

FRONT ECU 
ACK

SLEEP ACK or 
NORMAL ACK

Item No.

Item name

Normal 
condition

Item 32

DR DOOR SW

ON

Item 35

HD AUTO-CUT

OFF