Mitsubishi Galant (2004+). Manual - part 1596

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-277

STEP 3. Using scan tool MB991958, read the diagnostic 
trouble code.

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) Turn the ignition switch to the "ON" position.
(2) Check if the DTC is set.
(3) Turn the ignition switch to the "LOOK (OFF)" position.
Q: Is DTC B1540, B1541, B1542, B1543, B1545 or B1546 

set?
YES : Carry out the troubleshooting of the occupant 

classification-ECU or the occupant classification 
sensor system.  (Refer to 

P.52B-318

 <B1540, B1541, 

B1542 or B1543>, 

P.52B-320

 <B1545 or B1546>). 

NO :  Go to Step 4 .

STEP 4 Using scan tool MB991958, check actuator test.

• Item No.03: Passenger’s air bag OFF indicator light illumi-

nation

Q: Does the passenger’s air bag indicator light illuminate 

or go out normally?
YES : Go to Step 5 .
NO :  Relace the passenger’s air bag OFF indicator light 

(Refer to GROUP 52A, Instrument Panel Assembly 

P.52A-3

). Then go to Step 6 .

AC305412

AB

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-278

STEP 5. Check the harness between SRS-ECU connector 
C-121 (terminal No.21) and passenger’s air bag OFF 
indicator light C-06 (terminal No.3).

• Check the passenger’s air bag OFF indicator light output 

lines for open circuit.

NOTE: After inspecting intermediate connector C-22 inspect 
the wiring harness. If intermediate connector C-22 is damaged, 
repair or replace them. Refer to GROUP 00E, Harness Con-
nector Inspection 

P.00E-2

. Then go to Step 6  .

Q: Is the check result satisfactory?

YES : Erase the diagnostic trouble code memory, and check 

the diagnostic trouble code. If DTC B1489 sets, 
replace the SRS-ECU. (Refer to 

P.52B-365

.) Then go 

to Step 6 .

NO :  Repair the harness wires. Then go to Step 6 .

AC305233CX

CONNECTOR: C-06

HARNESS SIDE

AC305362

CONNECTOR: C-121

C-121 (Y)

AH

SRS-ECU

C-121
HARNESS SIDE 
CONNECTOR
(REAR VIEW)

42

31

38

27

21

41

28

39

22

30

25

47

36

33

44

34

45

37

48

26

29

23

40

32

43

35

46

24

B

A

AC305233 AI

CONNECTOR: C-22

C-22 (Y)

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-279

STEP 6. 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 B1489 set?

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

DTC B1499: SRS-ECU Air Bag Condition Monitor Detects Deployed  Air Bag 

CAUTION

If DTC B1499 is set in the SRS-ECU, always diag-
nose the CAN main bus line.

.

DTC SET CONDITIONS
This DTC is set after the air bag has deployed. If this 
DTC is set before the air bag has deployed, the 
cause is probably a malfunction inside the 
SRS-ECU.

.

TROUBLESHOOTING HINTS
Malfunction of the SRS-ECU

.

DIAGNOSIS

Required Special Tool:

• 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)

AC305412

AB

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-280

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 B1499 set?

YES : Replace the SRS-ECU (Refer to 

P.52B-365

).

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