Mitsubishi Galant (2004+). Manual - part 1581

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-217

STEP 7. Check the driver’s seat belt pre-tensioner circuit. 
Measure the resistance at the SRS-ECU connector C-122.

(1) Disconnect SRS-ECU connector C-122.

DANGER

To prevent the seat belt pre-tensioner from deploying 
unintentionally, disconnect the driver’s seat belt 
pre-tensioner connector D-21 to short the squib cir-
cuit.

(2) Disconnect driver's seat belt pre-tensioner connector D-21. 

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.

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 7, 8 and the short spring to release 
the short spring.

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

AC306920AC

CONNECTOR: D-21

D-21 (B)

FOWARD

CENTER
PILLAR

HARNESS SIDE
CONNECTOR
(FRONT VIEW)

2 1

AC103556 AT

LOCKING BUTTON

FLAT-TIP SCREW
DRIVER

D-21 HARNESS 
SIDE CONNECTOR

D-21 DRIVER'S 
SEAT BELT
PRE-TENSIONER
CONNECTOR

AC308180 AB

A

A

C-122 HARNESS SIDE
CONNECTOR (FRONT VIEW)

TERMINAL

CABLE TIE

SHORT SPRING

4 mm (0.16 inch) OR MORE

SEC-
TION
A - A

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-218

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 7 and 8.

It should be open circuit.

Q: Does continuity exist?

YES : Erase the diagnostic trouble code memory, and check 

the diagnostic trouble code. If DTC B1470 sets, 
replace the SRS-ECU (Refer to 

P.52B-365

). Then go 

to Step 9.

NO :  Go to Step 8.

STEP 8. Check the harness for short circuit between 
SRS-ECU connector C-122 (terminal No.7 and 8) and 
driver’s seat belt pre-tensioner connector D-21 (terminal 
No.1 and 2).

Q: Are harness wires between SRS-ECU connector C-122 

(terminal No.29 and 30) and driver’s seat belt 
pre-tensioner connector D-21 (terminal No.1 and 2) in 
good condition?
YES : Go to Step 9.
NO :  Replace the harness wires between SRS-ECU 

connector C-122 and driver’s seat belt pre-tensioner 
connector D-21. Then go to Step 9.

AC308179

A

B

18

10

15

7

13

5

14

6

16

8

17

9

19

11

20

12

1 2

3 4

C-122 CONNECTOR
HARNESS SIDE
(REAR VIEW)

AB

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

AC306920AC

CONNECTOR: D-21

D-21 (B)

FOWARD

CENTER
PILLAR

HARNESS SIDE
CONNECTOR
(FRONT VIEW)

2 1

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-219

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 B1470 set?

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

DTC B1471: Seat Belt Pre-Tensioner (LH) (Squib) System Fault 2 (Open in the Squib Circuit)

AC305412

AB

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

SEAT BELT
PRETENSIONER
(LH)

AIR BAG DRIVE CIRCUIT

SRS-ECU

CONNECTOR
LOCK SWITCH

CONNECTOR
LOCK SWITCH

Driver's Seat Belt Pre-Tensioner (Squib) Circuit

: CONNECTOR CONNECTED: ON

  CONNECTOR DISCONNECTED: OFF

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-220

CAUTION

If DTC B1471 is set in the SRS-ECU, always diag-
nose the CAN main bus line.

.

CIRCUIT OPERATION
The SRS-ECU judges how severe a collision is by 
detecting signals from the front impact sensors and 
the front air bag analog G-sensor. If the impact is 
over a predetermined level, the SRS-ECU sends an 
ignition signal. At this time, if the front air bag safing 
G-sensor is on, the pre-tensioner will deploy. 

.

DTC SET CONDITIONS
This DTC is set if there is abnormal resistance 
between the input terminals of the driver's seat belt 
pre-tensioner (squib).

.

TROUBLESHOOTING HITS

• Improper connector contact

• Open circuit in the driver's seat belt pre-tensioner 

(squib) circuit

• Malfunction of the SRS-ECU

.

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

• MB991865: Dummy resistor

• MB991884: Resister harness (For pre-tensioner)

AC305362

CONNECTOR: C-122

C-122 (Y)

AE

SRS-ECU

AC306920AB

CONNECTOR: D-21

D-21 (B)

FOWARD

CENTER
PILLAR