Mitsubishi Grandis. Manual - part 1015

TROUBLESHOOTING

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-112

NOTE: *: The squib circuit connectors integrate a 
"short" spring (which prevents the air bag from 
deploying unintentionally due to static electricity by 
shorting the positive wire to the earth wire in the 
squib circuit when the connectors are disconnected). 
Therefore, if connector C-120, G-22 or G-01 is 
damaged or improperly engaged, the short spring 
may not be released when the connector is 
connected.

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 line (Refer to GROUP 
54D, Diagnosis 

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. MUT-III diagnosis code

CAUTION

To prevent damage to MUT-II/III, always turn the 
ignition switch to the "LOCK" (OFF) position 
before connecting or disconnecting MUT-II/III.
(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-120 (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 B1450 set?

YES : 

Go to Step 5.

NO : 

The procedure is complete. It is assumed 
that diagnosis code B1450 set as connector 
C-120 was engaged improperly.

AC311438 AE

C-120 (Y)

Connector: C-120

Harness side
(front view)

TROUBLESHOOTING

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-113

STEP 5. Connector lock check: SRS-ECU 
connector C-120, curtain air bag module (LH) 
connector G-01 and intermediate connector 
G-22. (MUT-III diagnosis code.)
(1) Disconnect the negative battery terminal.

(2) Disconnect connectors C-120, G-22 and G-01, 

and then reconnect them. For connector G-01, 
use a flat-tipped screwdriver to pull out the 
locking button at the harness side connector, and 
then disconnect the connector.

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

diagnosis code.

Q: Is diagnosis code B1450 set?

YES : 

Go to Step 6.

NO : 

The procedure is complete. It is assumed 
that diagnosis code B1450 set as connector 
C-120, G-22 or G-01 was engaged 
improperly.

STEP 6. Check the intermediate connector. 
(MUT-III diagnosis code)
(1) Disconnect the negative battery terminal.

(2) Remove the intermediate connector G-22 

(connection between curtain air bag harness and 
floor harness).

(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 resistor harness probe into 

intermediate connector G-22 (floor harness side) 
by backprobing.

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

the diagnosis code.

Q: Is diagnosis code B1450 set?

YES : 

Go to Step 7.

NO : 

Go to Step 8.

AC311438 AE

C-120 (Y)

Connector: C-120

Harness side
(front view)

AC302576AE

 G-22 (R)

Connector: G-22

Floor harness
side (front view)

Third seat
belt (LH)

Second seat
belt (LH)

2 1

AC303223

AC 

 G-01 (B)

Connector: G-01

Harness side
(front view)

Roof centre duct

AC302576AE

 G-22 (R)

Connector: G-22

Floor harness
side (front view)

Third seat
belt (LH)

Second seat
belt (LH)

2 1

AC006042CA

MB991866
(Resistor harness)

G-22 Floor harness
connector

G-22 Rear floor
harness connector

MB991865
(Dummy resistor : 3

ΩΩ

TROUBLESHOOTING

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-114

STEP 7. Check the curtain air bag module (LH) 
circuit. Resistance measurement at the SRS-ECU 
connector C-120.

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

DANGER

To prevents the air bag from deploying 
unintentionally, disconnect the intermediate 
connector G-22 to short the squib circuit.

(2) Disconnect the intermediate connector G-22.

CAUTION

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

between terminals 5, 6 and the short spring to 
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) Resistance measurement between C-120 

harness side connector terminals 5 and 6.

OK: Open circuit

Q: Is the check result normal?

YES : 

Go to Step 9.

NO : 

Repair the harness wire between SRS-ECU 
connector C-120 (terminal No.5 and 6) and 
intermediate connector G-22 (terminal No.1 
and 2).

AC311438 AE

C-120 (Y)

Connector: C-120

Harness side
(front view)

AC302576AE

 G-22 (R)

Connector: G-22

Floor harness
side (front view)

Third seat
belt (LH)

Second seat
belt (LH)

2 1

AC301604

Section
A - A

C-120
Harness side connector
(front view)

Cable tie

Short spring

4 mm or more

Terminal

AC

A

A

AC301560

A

B

18

10

15

7

13

5

14

6

16

8

17

9

19

11

20

12

1 2

3 4

AC

C-120
Harness side connector 
(rear view)

TROUBLESHOOTING

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-115

STEP 8. Check the curtain air bag module (LH) 
circuit. Resistance measurement at the 
intermediate connector G-22.
(1) Disconnect the negative battery terminal.

DANGER

To prevents the air bag from deploying 
unintentionally, disconnect the curtain air 
bag module (LH) connector G-01 to short the 
squib circuit.

(2) Disconnect curtain air bag module (LH) 

connector G-01. Use a flat-tipped screwdriver to 
unlock the locking button at the harness side 
connector by withdrawing it toward you in two 

stages, and then disconnect the connector.

(3) Disconnect the intermediate connector G-22.

CAUTION

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

between terminals 1, 2 and the short spring to 
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.

(5) Resistance measurement between G-22 rear 

floor harness connector terminals 1 and 2.

OK: Open circuit

Q: Is the check result normal?

AC303223

AC 

 G-01 (B)

Connector: G-01

Harness side
(front view)

Roof centre duct

AC208384AN

G-01
Curtain air bag
module connector 

Flat-tip screw
driver

Locking button

G-01
Harness side
connector

AC302576AE

 G-22 (R)

Connector: G-22

Floor harness
side (front view)

Third seat
belt (LH)

Second seat
belt (LH)

2 1

AC303537

4 mm or more

G-22 Rear floor 
harness connector 
(front view)

Terminal

Cable tie

A

Short
spring

Section
A - A

AF

A

1 2

2

1

AC303985AC

G-22 Rear floor harness 
connector (rear view)

<G-01 
Harness 
connector>
Special tool 
MB991884
(front view)