Mitsubishi Grandis. Manual - part 152

SYMPTOM PROCEDURES

SMART WIRING SYSTEM (SWS) USING SWS MONITOR

54C-70

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

CAUTION

Whenever the ECU is replaced, ensure that the 
power supply circuit, the earthing circuit and the 
communication circuit are normal.

SYMPTOM PROCEDURES

SMART WIRING SYSTEM (SWS) USING SWS MONITOR

54C-71

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

IGNITION
SWITCH (IG2)

DIAGNOSIS
CONNECTOR

ETACS-ECU

POWER
SOURCE

FRONT-ECU

26

FUSIBLE
LINK

RELAY
BOX

FRONT SIDE

Front-ECU Power Supply and SWS Communication Circuit

SYMPTOM PROCEDURES

SMART WIRING SYSTEM (SWS) USING SWS MONITOR

54C-72

COMMENTS ON TROUBLE SYMPTOM

It is suspected that the power supply circuit to the 
front-ECU is defective, or the wiring harness 
between the SWS monitor and the front-ECU or their 
connector(s) is damaged. If the battery power supply 
circuit to the ECU (terminal No.7 of the front-ECU) is 
damaged, also check the power supply circuit from 
the ignition switch (IG2) (terminal No.30 of the 
front-ECU), and repair if necessary.

POSSIBLE CAUSES

• Malfunction of the front-ECU

• Malfunction of the ETACS-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 
ETACS-ECU and the SWS communication lines are 
normal.

• Ignition switch: OFF

ECUS TO BE CHECKED

• ETACS ECU

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

Q: Is the check result normal?

YES : 

Go to Step 2.

NO : 

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

P.54C-63

."

Step 2. Connector check: A-14X front-ECU 
connector

Q: Is the check result normal?

YES : 

Go to Step 3.

NO : 

Repair the defective connector.

Step 3. Voltage measurement at A-14X front-ECU 
connector.

(1) Disconnect the connector, and measure at the 

relay box side.

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

No.7 and body earth

OK: System voltage

Q: Is the check result normal?

YES : 

Go to Step 6.

NO : 

Go to Step 4.

Step 4. Check the wiring harness between A-14X 
front-ECU connector terminal No.7 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.

AC311521AB

Connector: A-14X

Relay box side

AC311521AB

Connector: A-14X

Relay box side

AC310507CJ

Connector A-14X 
(Harness side)

AC311521AB

Connector: A-14X

Relay box side

SYMPTOM PROCEDURES

SMART WIRING SYSTEM (SWS) USING SWS MONITOR

54C-73

Step 5. Connector check: A-15X front-ECU 
connector

Q: Is the check result normal?

YES : 

Go to Step 6.

NO : 

Repair the defective connector.

Step 6. Resistance measurement at A-15X 
front-ECU connector.

(1) Disconnect the connector, and measure at the 

relay box side.

(2) Resistance between A-15X front-ECU connector 

terminal No.31 and body earth

OK: 2 

Ω or less

Q: Is the check result normal?

YES : 

Go to Step 9.

NO : 

Go to Step 7.

Step 7. Connector check: A-25 earth connector

Q: Is the check result normal?

YES : 

Go to Step 8.

NO : 

Repair the defective connector.

AC311521AC

Connector: A-15X

Relay box side

21

22

23

24

25

26

27

28

29

30

31

AC311521AC

Connector: A-15X

Relay box side

21

22

23

24

25

26

27

28

29

30

31

AC310506BV

Connector A-15X 
(Harness side)

21

22

23

24

25

26

27

28

29

30

31

AC310403

A-25 (GR)

AE

Connector: A-25 <LHD>

Harness side

AC310398

A-25 (GR)

AE

Connector: A-25 <RHD>

Harness side