Mitsubishi Grandis. Manual - part 126

INPUT SIGNAL PROCEDURES

SMART WIRING SYSTEM (SWS) NOT USING SWS MONITOR

54B-501

Inspection Procedure Q-19: The driver's seat belt switch signal is not received. <RH drive vehicles>

CAUTION

Whenever the ECU is replaced, ensure that the 
input signal circuit is normal.

COMMENTS ON TROUBLE SYMPTOM

Input signal from the driver's seat belt switch signal is 
used to operate the seat belt warning buzzer function 
and seat belt warning lamp. If the signal is abnormal, 
the seat belt warning buzzer function and seat belt 
warning lamp will not work normally.

POSSIBLE CAUSES

• Malfunction of the driver's seat belt switch

• Malfunction of the ETACS-ECU

• Malfunction of the combination meter

• Damaged harness wires and connectors

DIAGNOSTIC PROCEDURE

Step 1. MUT-III CAN bus diagnostics
Use the MUT-III to diagnose the CAN bus lines.

Q: Is the check result normal?

YES : 

Go to Step 2.

NO : 

Repair the CAN bus line (Refer to GROUP 
54D 

− Diagnosis 

P.54D-16

).

Step 2. MUT-III diagnosis code
Check whether the combination meter-related 
diagnosis code is set.

Q: Is the diagnosis code set?

YES : 

Diagnose the combination meter (Refer to 

GROUP 54A 

− Combination meter 

P.54A-35

).

NO : 

Go to Step 3.

COMBINATION METER

SEAT BELT
SWITCH (RH)

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

Driver's Seat Belt Switch Input Circuit <RHD>

ETACS-ECU

CAN COMMUNICATION LINE
(CAN_L LINE)

CAN COMMUNICATION LINE
(CAN_H LINE)

INPUT SIGNAL PROCEDURES

SMART WIRING SYSTEM (SWS) NOT USING SWS MONITOR

54B-502

Step 3. Connector check: D-26 seat belt switch 
(RH) connector

Q: Is the check result normal?

YES : 

Go to Step 4.

NO : 

Repair the defective connector.

Step 4. Check the seat belt switch (RH).
Refer to GROUP 52A 

− Front seat belt 

P.52A-36

.

Q: Is the check result normal?

YES : 

Go to Step 5.

NO : 

Replace the inner seat belt (driver's side).

Step 5. Resistance measurement at the D-26 seat 
belt switch (RH) connector.

(1) Disconnect the connector, and measure at the 

wiring harness side.

(2) Resistance between D-26 seat belt switch (RH) 

connector terminal No.2 and body earth

OK: 2 

Ω or less

Q: Is the check result normal?

YES : 

Go to Step 7.

NO : 

Go to Step 6.

Step 6. Check the wiring harness between D-26 
seat belt switch (RH) connector terminal No.2 
and body earth.

• Check the earth wires for open circuit.

Q: Is the check result normal?

YES : 

Replace the inner seat belt (driver's side).

NO : 

Repair the wiring harness.

Step 7. Connector check: C-02 combination 
meter connector

Q: Is the check result normal?

YES : 

Go to Step 8.

NO : 

Repair the defective connector.

AC312058

Harness side

AC

Connector: D-26 <RHD>

AC312058

Harness side

AC

Connector: D-26 <RHD>

AC312730AP

Connector D-26
(Harness side)

AC312058

Harness side

AC

Connector: D-26 <RHD>

AC312043

Connector: C-02 <RHD>

AK

Harness side

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INPUT SIGNAL PROCEDURES

SMART WIRING SYSTEM (SWS) NOT USING SWS MONITOR

54B-503

Step 8. Check the wiring harness from D-26 seat 
belt switch (RH) terminal No.1 to C-02 
combination meter connector terminal No.32.

NOTE: 

Prior to the wiring harness inspection, check 
intermediate connector C-16, and repair if necessary.

• Check the input line for open circuit.

Q: Is the check result normal?

YES : 

Go to Step 9.

NO : 

Repair the wiring harness.

Step 9. Retest the system.
After the ETACS-ECU is replaced, check that the 
driver's seat belt switch signal is received.
(1) Replace the ETACS-ECU.
(2) Check that the driver's seat belt switch signal is 

received.

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 combination meter.

AC312043

Connector: C-02 <RHD>

AK

Harness side

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AC312058

Harness side

AC

Connector: D-26 <RHD>

AC312043

Connector: C-16 <RHD>

AH

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4243

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INPUT SIGNAL PROCEDURES

SMART WIRING SYSTEM (SWS) NOT USING SWS MONITOR

54B-504

Inspection Procedure Q-20: The front passenger's seat belt switch signal is not received.<LH drive 
vehicles>

CAUTION

Whenever the ECU is replaced, ensure that the 
input signal circuit is normal.

COMMENTS ON TROUBLE SYMPTOM

Input signal from the passenger’s seat belt switch is 
used to operate the seat belt warning buzzer function 
and seat belt warning lamp. If the signal is abnormal, 
the seat belt warning buzzer function and seat belt 
warning lamp will not work normally.

POSSIBLE CAUSES

• Malfunction of the passenger’s seat belt switch

• Malfunction of the seat occupancy sensor

• Malfunction of the ETACS-ECU

• Damaged harness wires and connectors

DIAGNOSTIC PROCEDURE

Step 1. Connector check: D-26 seat belt switch 
(LH) connector

Q: Is the check result normal?

ETACS-
ECU

SEAT
BELT
SWITCH
(RH)

SEAT
OCCUPANCY
SENSOR

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

Passenger's Seat Belt Switch Input Circuit <LHD>

AC312051

Connector: D-26 <LHD>

Harness side

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