Mitsubishi Galant 9G. Manual - part 1450

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-210

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 ).

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 DTCs 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 Use Troubleshooting/Inspection 
Service Points 

− How to Cope with Intermittent 

Malfunctions ).

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-211

DTC B1470: Seat Belt Pre-Tensioner (LH) (Squib) System Fault 1 (Short Circuit between Terminals of 
the Squib Circuit)

CAUTION

If DTC B1470 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 side seat 
belt pre-tensioner (squib).

.

TROUBLESHOOTING HITS

• Improper engaged connector or defective short 

spring*

• Short circuit between the driver's seat belt 

pre-tensioner (squib) circuit terminals

• Damaged connector(s)

• Malfunction of the SRS-ECU

.

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

SEAT BELT
PRE-TENSIONER
(LH)

PRE-TENSIONER(LH)
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

AC306920AB

CONNECTOR: D-21

D-21 (B)

FOWARD

CENTER
PILLAR

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-212

NOTE: *: The squib circuit connectors integrate a 
"short" spring (which prevents the seat belt pre-ten-
sioner from deploying unintentionally due to static 
electricity by shorting the positive wire to the ground 
wire in the squib circuit when the connectors are dis-
connected) (Refer to 

P.52B-3

). Therefore, if connec-

tor C-122 or D-21 is damaged or improperly 
engaged, the short spring may not be released when 
the connector is connected.

.

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 resister

• MB991884: Resister harness (For Pre-tensioner)

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 ). 

AC305412

AB

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-213

STEP 2. Recheck for diagnostic trouble code.
Check again if the DTC is set.
(1) Erase the DTC.
(2) Turn the ignition switch to "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 Use Troubleshooting/Inspection 
Service Points 

− How to Cope with Intermittent 

Malfunctions ).

STEP 3. Using scan tool MB991958, read the diagnostic 
trouble code.
(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 B1519 set?

YES : Go to Step 4.
NO :  Go to Step 5.

AC305412

AB

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

AC305412

AB

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827