Mitsubishi Grandis. Manual - part 1007

TROUBLESHOOTING

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-80

STEP 2. Check whether the diagnosis code is 
reset.

Check again if the diagnosis code is set.
(1) Erase the diagnosis code.
(2) Ignition: LOCK (OFF) position to ON
(3) On completion, check that the diagnosis code is 

not reset.

Q: Is the diagnosis code set?

YES : 

Go to Step 3.

NO : 

There is an intermittent malfunction such as 
poor engaged connector(s) or open circuit 
(Refer to GROUP 00, How to Cope with 
Intermittent Malfunction 

P.00-5

).

STEP 3. MUT-III diagnosis code

CAUTION

To prevent damage to MUT-III MB991958, always 
turn the ignition switch to the "LOCK" (OFF) 
position before connecting or disconnecting 
MUT-III MB991958.
(1) Turn the ignition switch to the "ON" position.
(2) Check if the diagnosis code is set.
(3) Turn the ignition switch to the "LOOK (OFF)" 

position.

Q: Is diagnosis code B1519 set?

YES : 

Go to Step 4.

NO : 

Go to Step 5.

STEP 4. Connector lock check: SRS-ECU 
connector C-140 (MUT-III diagnosis code).
(1) Disconnect the negative battery terminal.

(2) Disconnect connectors C-120 and then 

reconnect them.

(3) Connect the negative battery terminal.
(4) Erase the diagnosis code memory, and check the 

diagnosis code.

Q: Is diagnosis code B1430 out put?

YES : 

Go to Step 5.

NO : 

The procedure is complete. It is assumed 
that diagnosis code B1430 set as connector 
C-120 was engaged improperly.

STEP 5. Connector lock check: SRS-ECU 
connector C-120 and side-airbag module (LH) 
connector D-22 (MUT-III diagnosis code)
(1) Disconnect the negative battery terminal.

(2) Disconnect connectors C-120 and D-22 and then 

reconnect them.

(3) Connect the negative battery terminal.
(4) Erase the diagnosis code memory, and check the 

diagnosis code.

Q: Is diagnosis code B1430 out put?

YES : 

Go to Step 6.

NO : 

The procedure is complete. It is assumed 
that diagnosis code B1430 set because 
connector C-120 or D-22 was engaged 
improperly.

STEP 6. Check the side-airbag module (LH). 
(MUT-III diagnosis code.)
(1) Disconnect the negative battery terminal.

(2) Disconnect the side-airbag module (LH) 

AC311438 AE

C-120 (Y)

Connector: C-120

Harness side
(front view)

AC311438 AE

C-120 (Y)

Connector: C-120

Harness side
(front view)

AC303521

AD

D-22 (R)

Connector: D-22

Harness side
(front view)

AC303521

AD

D-22 (R)

Connector: D-22

Harness side
(front view)

TROUBLESHOOTING

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-81

connector D-22.

(3) Connect special tool dummy resistor (MB991865) 

to special tool resistor harness (MB991866).

CAUTION

Do not insert a test probe into the terminal from 
its front side directly, as the connector contact 
pressure may be weakened.
(4) Insert special tool MB991866 into the D-22 

harness side connector by backprobing.

(5) Connect the negative battery terminal.
(6) Erase diagnosis code memory, and check the 

diagnosis code. 

Q: Is diagnosis code B1430 set?

YES : 

Go to Step 7.

NO : 

Replace the seatback frame of the front 
seat (LH). (Refer to GROUP 52A, Front 
Seat 

P.52A-24

).

STEP 7. Check the side-airbag module (LH) 
circuit. Resistance measurement at the SRS-ECU 
connector C-120.

(1) Disconnect SRS-ECU connector C-120.

DANGER

To prevent the air bag from deploying 
unintentionally, disconnect the side-airbag 
module (LH) connector D-22 to short the 
squib circuit.

(2) Disconnect left hand side-airbag module (LH) 

connector D-22.

CAUTION

Insert an insulator such as a cable tie to a depth 
of 4mm (0.16 inch) or more, otherwise the short 
spring will not be released.
(3) Insert a cable tie [3 mm wide, 0.5 mm thick] 

between terminals 9, 10 and the short spring to 

AC006042 BY

MB991866
(Resistor harness)

D-22 Harness side
connector

D-22 Side-airbag
module (LH) connector

MB991865 (Dummy
resistor: 3

 

Ω)

AC311438 AE

C-120 (Y)

Connector: C-120

Harness side
(front view)

AC303521

AD

D-22 (R)

Connector: D-22

Harness side
(front view)

AC308180 AD

A

A

C-120 Harness side
connector (front view)

Terminal

Cable tie

Short spring

4 mm or more

Sec-
tion
A - A

TROUBLESHOOTING

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-82

release the short spring.

CAUTION

Do not insert a test probe into the terminal from 
its front side directly, as the connector contact 
pressure may be weakened.
(4) Check for continuity between C-120 harness side 

connector terminals 9 and 10.

OK: Open circuit

Q: Is the check result normal? 

YES : 

Go to Step 8. 

NO : 

Repair the harness wires between 
SRS-ECU connector C-120 (terminal No.9 
and 10) and side-airbag module (LH) 
connector D-22 (terminal No.1 and 2).

STEP 8. Check whether the diagnosis code is 
reset.

Q: Is diagnosis code B1430 set?

YES : 

Replace the SRS-ECU (Refer to 

P.52B-223

).

NO : 

An intermittent malfunction is suspected 
(Refer to GROUP 00, How to Use 
Troubleshooting/Inspection Service Points 

P.00-5

).

Code No.B1431: Side-Airbag Module (LH) (Squib) System Fault 2 (Open in the Squib Circuit)

AC308174

A

B

18

10

15

7

13

5

14

6

16

8

17

9

19

11

20

12

1 2

3 4

C-120 Harness side
connector (rear view)

AE

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

SIDE AIR BAG
MODULE
(SQUIB) (LH)

SRS-ECU

CONNECTOR
LOCK SWITCH

CONNECTOR
LOCK SWITCH

: CONNECTOR 
  CONNECTED: ON
  CONNECTOR 
  DISCONNECTED: OFF

NOTE

Side-Airbag Module (LH) (Squib) Circuit

TROUBLESHOOTING

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-83

CAUTION

If diagnosis code B1431 is set in the combination 
meter, always diagnose the CAN bus lines.

OPERATION

• The SRS-ECU judges how severe a collision is 

by detecting signals from the left and right side 
impact sensors. If the impact is over a 
predetermined level, the SRS-ECU sends an 
ignition signal. At this time, if the side-airbag 
safing G-sensor is on, the SRS side-airbag will 
inflate.

• The ignition signal is input to the side-airbag 

module to inflate the side-airbag.

DIAGNOSIS CODE SET CONDITIONS

This diagnosis code is set if there is abnormal 
resistance between the input terminals of the 
side-airbag module (LH) (squib).

PROBABLE CAUSES

• Open circuit in the side-airbag module (squib) 

(LH) circuit

• Improper connector contact

• Malfunction of the SRS-ECU

DIAGNOSIS 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 lines (Refer to GROUP 
54D, Diagnosis-Can Bus Diagnostic Chart 

P.54D-16

).

STEP 2. Check whether the diagnosis code is 
reset.

Check again if the diagnosis code is set.
(1) Erase the diagnosis code.
(2) Ignition: LOCK (OFF) position to ON
(3) On completion, check that the diagnosis code is 

not reset.

Q: Is the diagnosis code set?

YES : 

Go to Step 3.

NO : 

There is an intermittent malfunction such as 
poor engaged connector(s) or open circuit 
(Refer to GROUP 00, How to Cope with 
Intermittent Malfunction 

P.00-5

).

STEP 3. Check the side-airbag module (LH). 
(MUT-III diagnosis code.)
(1) Disconnect the negative battery terminal.

(2) Disconnect the side-airbag module (LH) 

connector D-22.

(3) Connect special tool dummy resistor (MB991865) 

to special tool resistor harness (MB991866).

CAUTION

Do not insert a test probe into the terminal from 
its front side directly, as the connector contact 
pressure may be weakened.
(4) Insert special tool MB991866 into the D-22 

harness side connector by backprobing.

(5) Connect the negative battery terminal.
(6) Erase diagnosis code memory, and then check 

the diagnosis code. 

Q: Is diagnosis code B1431 set?

YES : 

Go to Step 4.

NO : 

Replace the seatback frame of the front 
seat (LH). (Refer to GROUP 52A, Front 
Seat 

P.52A-24

).

AC303521

AD

D-22 (R)

Connector: D-22

Harness side
(front view)

AC006042 BY

MB991866
(Resistor harness)

D-22 Harness side
connector

D-22 Side-airbag
module (LH) connector

MB991865 (Dummy
resistor: 3

 

Ω)