Mitsubishi Grandis. Manual - part 203

SYMPTOM PROCEDURES

SMART WIRING SYSTEM (SWS) USING SWS MONITOR

54C-274

"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

."

Step 2. Function diagnosis by using the SWS 
monitor.

Check the SWS communication signal, which are 
related to the tail lamps.

<Selected item> LIGHTING - TAIL LAMP

• Ignition switch: ON

• Lighting switch: TAIL

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 00, 01 or 
03. : 

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.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. Connector check: A-14X front-ECU 
connector.

Q: Is the check result normal?

YES : 

Go to Step 4.

NO : 

Repair the defective connector.

Step 4. Voltage measurement at A-14X front-ECU 
connector.

(1) Remove the front-ECU, and measure at the relay 

box side.

(2) Voltage between A-14X front-ECU connector 

terminal No.5 and body earth

OK: System voltage

Q: Is the check result normal?

YES : 

Go to Step 6.

NO : 

Go to Step 5.

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 03

PASSING SW

OFF

Item 30

IG SW(IG1)

ON

Item 35

HD AUTO-CUT

OFF

Item 70

FRONT ECU ACK

NORMAL ACK

AC311521AB

Connector: A-14X

Relay box side

AC311521AB

Connector: A-14X

Relay box side

AC310507CE

Connector A-14X 
(Relay box side)

SYMPTOM PROCEDURES

SMART WIRING SYSTEM (SWS) USING SWS MONITOR

54C-275

Step 5. Check the wiring harness between A-14X 
front-ECU connector terminal No.5 and the 
fusible link (26).

• Check the power supply line for open circuit.

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 : 

Repair the wiring harness.

Step 6. Retest the system.

Check that the tail/stop lamps 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-2: The low-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 low-beam headlamps do not illuminate, the 
headlamp 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

AC311521AB

Connector: A-14X

Relay box side

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: LO

RELAY
BOX

INPUT SIGNAL

· HEADLAMP AUTOMATIC
  SHUTDOWN
· HEADLAMP SWITCH

HEADLAMP (LO: LH)

HEADLAMP (LO: RH)

Headlamp Relay (Low-Beam) Circuit

FUSIBLE LINK 

26

SYMPTOM PROCEDURES

SMART WIRING SYSTEM (SWS) USING SWS MONITOR

54C-276

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

."

Step 2. Function diagnosis by using the SWS 
monitor.

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

<Selected item> LIGHTING - HEADLAMP LO

• Ignition switch: ON

• Lighting switch: HEAD

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 No.00 or 
03. : 

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.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. Connector check: A-14X front-ECU 
connector.

Q: Is the check result normal?

YES : 

Go to Step 4.

NO : 

Repair the defective connector.

Step 4. Voltage measurement at A-14X front-ECU 
connector.

(1) Remove the front-ECU, and measure at the relay 

Item No.

Item name

Normal 
condition

Item 00

HEADLAMP SW

ON

Item 03

PASSING SW

OFF

Item 30

IG SW(IG1)

ON

Item 35

HD AUTO-CUT

OFF

Item 70

FRONT ECU ACK

NORMAL ACK

AC311521AB

Connector: A-14X

Relay box side

AC311521AB

Connector: A-14X

Relay box side

SYMPTOM PROCEDURES

SMART WIRING SYSTEM (SWS) USING SWS MONITOR

54C-277

box side.

(2) Voltage between A-14X front-ECU connector 

terminal Nos.3, 4 and body earth

OK: System voltage

Q: Is the check result normal?

YES : 

Go to Step 6.

NO : 

Go to Step 5.

Step 5. Check the wiring harness between A-14X 
front-ECU connector terminal Nos.3, 4 and the 
fusible link (26).

• Check the power supply line for open circuit.

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 : 

Repair the wiring harness.

Step 6. Retest the system.

Check that the low-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.

AC310507CD

Connector A-14X
(Relay box side)

AC311521AB

Connector: A-14X

Relay box side