Mitsubishi Galant 9G. Manual - part 1437

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-158

STEP 7. Check the side-airbag module (LH) circuit. 
Measure the resistance at the SRS-ECU connector C-122.
(1) Disconnect SRS-ECU connector C-122.

DANGER

To prevent the air bag from deploying unintentionally, 
disconnect the side-airbag module (LH) connector 
D-24 to short the squib circuit.

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

D-24.

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 (0.12 inch) wide, 0.5 mm (0.02 inch) 

thick] between terminals 9, 10 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) Check for continuity between C-122 harness side connector 

terminals 9 and 10.
It should be open circuit.

Q: Is the circuit normal? 

YES : Erase the diagnostic trouble code memory, and check 

the diagnostic trouble code. If DTC B1430 sets, 
replace the SRS-ECU (Refer to 

P.52B-365

). Then go 

to Step 9. 

NO :  Go to Step 8. 

AC305362

CONNECTOR: C-122

C-122 (Y)

AI

SRS-ECU

C-122 
Harness side
connector 
(rear view)

A

B

18

10

15

7

13

5

14

6

16

8

17

9

19

11

20

12

1 2

3 4

AC307778

CONNECTOR : D-24

AC

D-24 (R)

2

1

HARNESS SIDE
CONNECTOR
(REAR VIEW)

AC308175AB

A

A

C-122 HARNESS SIDE
CONNECTOR (FRONT VIEW)

TERMINAL

SHORT SPRING

4 mm (0.16 inch) OR MORE

SEC-
TION
A - A

CABLE TIE

AC308174

A

B

18

10

15

7

13

5

14

6

16

8

17

9

19

11

20

12

1 2

3 4

C-122 HARNESS SIDE
CONNECTOR
(REAR VIEW)

AB

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-159

STEP 8. Check the harness wires for short circuit between 
SRS-ECU connector C-122 (terminal No.9 and 10) and 
side-airbag module (LH) connector D-24 (terminal No.1 and 
2).
Q: Are the harness wires between SRS-ECU connector 

C-122 (terminal No.9 and 10) and side-airbag module 
(LH) connector D-24 (terminal No.1 and 2) in good 
condition?
YES : Go to Step 9.
NO :  Replace the harness wires between SRS-ECU 

connector C-110 and side-airbag module (LH) 
connector D-24. Then go to Step 9.

STEP 9. Recheck for diagnostic trouble code. 
Check again if the DTC is set.
(1) Erase the DTC.
(2) Turn the ignition switch to the "ON" position.
(3) Check if the DTC is set.
(4) Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is DTC B1430 set?

YES : Return to Step 1.
NO :  The procedure is complete.

AC305362

CONNECTOR: C-122

C-122 (Y)

AI

SRS-ECU

C-122 
Harness side
connector 
(rear view)

A

B

18

10

15

7

13

5

14

6

16

8

17

9

19

11

20

12

1 2

3 4

AC307778

CONNECTOR : D-24

AC

D-24 (R)

2

1

HARNESS SIDE
CONNECTOR
(REAR VIEW)

AC305412

AB

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-160

DTC B1431: Side-Airbag Module (LH) (Squib) System Fault 2 (Open in the Squib Circuit)

CAUTION

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

.

CIRCUIT 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 predeter-
mined level, the SRS-ECU sends an ignition sig-
nal. 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.

.

DTC SET CONDITIONS

This DTC is set if there is abnormal resistance 
between the input terminals of the side-airbag mod-
ule (LH) (squib).

.

TROUBLESHOOTING HINTS

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

(LH) circuit

• Improper connector contact

• Malfunction of the SRS-ECU

.

Side-Airbag Module (LH) (Squid) Circuit

SIDE AIR BAG MODULE
(SQUIB) (LH)

AIR BAG DRIVE CIRCUIT

SRS-ECU

CONNECTOR
LOCK SWITCH

CONNECTOR
LOCK SWITCH

: CONNECTOR CONNECTED
 : ON
  CONNECTOR DICONNECTED
 : OFF

NOTE

AC305362

CONNECTOR: C-122

C-122 (Y)

AE

SRS-ECU

AC307778

CONNECTOR : D-24

AB

D-24 (R)

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-161

DIAGNOSIS

Required Special Tools:

•  MB991958: Scan Tool (MUT-III Sub Assembly)

• MB991824: Vehicle Communication Interface (V.C.I.)

• MB991827: MUT-III USB Cable

• MB991910: MUT-III Main Harness A (Vehicles with CAN 

communication system)

• MB991865: Dummy resistor

• MB991866: Resister harness

STEP 1. Using scan tool MB991958, diagnose the CAN bus 
line.

CAUTION

To prevent damage to scan tool MB991958, always turn the 
ignition switch to the "LOCK" (OFF) position before con-
necting or disconnecting scan tool MB991958.
(1) Connect scan tool MB991958. Refer to "How to connect the 

scan tool 

P.52B-30

."

(2) Turn the ignition switch to "ON" position.
(3) Diagnose the CAN bus line.
(4) Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is the check result satisfactory?

YES : Go to Step 2
NO :  Repair the CAN bus lines (Refer to GROUP 54C, 

Diagnosis-Can Bus Diagnostic Chart ).

AC305412

AB

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827