Mitsubishi Galant (2004+). Manual - part 1582

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-221

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 the "ON" position.
(3) Diagnose the CAN bus line.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the CAN bus line found to be normal?

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

Diagnosis 

P.54C-14

).

STEP 2. 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 the DTC 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.00-6

).

AC305412

AB

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

AC305412

AB

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-222

STEP 3. Check the driver's seat belt pre-tensioner. (Using 
scan tool MB991958, read the diagnostic trouble code.)

(1) Disconnect the negative battery terminal.
(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.

(3) Connect special tool MB991865 to special tool MB991884.
(4) Connect special tool MB991884 to the D-21 harness side 

connector.

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

diagnostic trouble code.

Q: Is DTC B1471 set?

YES : Go to Step 4.
NO :  Replace the driver's seat belt pre-tensioner (Refer to 

P.52B-380

). Then go to Step 5. 

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

MB991884
MB991885

AC103283AO

MB991865
(DUMMY RESISTOR : 3

Ω)

MB991884
(RESISTOR 
HARNESS)

D-21  HARNESS SIDE 
CONNECTOR

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-223

STEP 4. Check the harness for open circuit between 
SRS-ECU connector C-122 (terminal No.7 and 8) and the 
driver's seat belt pre-tensioner D-21 (terminal No.1 and 2).

(1) Disconnect SRS-ECU connector C-122 and driver's seat 

belt pre-tensioner connector D-21, and measure at the 
wiring harness side. For 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.

(2) Connect D-21 harness side connector to special tool 

MB991884.

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

AC201287AT

D-21
HARNESS SIDE 
CONNECTOR

MB991884

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-224

CAUTION

Do not insert a test probe into the terminal from its front 
side directly, as the connector contact pressure may be 
weakened.
(3) Check for continuity between the following terminals. It 

should be less than 2 ohms.

• SRS-ECU connector C-122 (terminal No.7) and the spe-

cial tool (terminal No.2)

• SRS-ECU connector C-122 (terminal No.8) and the spe-

cial tool (terminal No.1)

Q: Does continuity exist?

YES : Erase the diagnostic trouble code memory, and 

recheck if any DTC set. If DTC B1471 set, replace the 
SRS-ECU (Refer to 

P.52B-365

). Then go to Step 5.

NO :  Replace harness wires between SRS-ECU connector 

C-122 and driver’s seat belt pre-tensioner connector 
D-21. Then go to Step 5.

STEP 5. Check 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 B1471 set?

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

AC308183

2

1

A

B

18

10

15

7

13

5

14

6

16

8

17

9

19

11

20

12

1 2

3 4

AB

<D-21 HARNESS SIDE
CONNECTOR>
SPECIAL TOOL
MB991884
(FRONT VIEW)

C-122 HARNESS SIDE
CONNECTOR
(REAR VIEW)

AC305412

AB

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827