Mitsubishi Galant (2004+). Manual - part 1572

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-181

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)

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

).

AC305412

AB

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-182

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

).

STEP 3. Check for any diagnostic trouble code. (Using 
scan tool MB991958, read the diagnostic trouble code.)

Check the side impact sensor (LH).
(1) Disconnect the negative battery terminal.
(2) Replace the side impact sensor (LH) with the side impact 

sensor (RH).

(3) Connect the negative battery terminal.
(4) Erase diagnostic trouble code from memory, and check the 

diagnostic trouble code.

Q: Is DTC B1428 or B1429 set?

YES : Replace the side impact sensor (LH) with a new one. 

(Refer to 

P.52B-377

). Go to Step 5.

NO :  Go to Step 4.

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-183

STEP 4. Check the harness wires for open circuit or short 
circuit between SRS-ECU connector C-122 (terminal No.19 
and 20) and side impact sensor (LH) connector D-21 
(terminal No.1 and 2).

Q: Are the harness wires between SRS-ECU connector 

C-122 (terminal No.19 and 20) and side impact sensor 
(LH) connector D-21 (terminal No.1 and 2) in good 
condition? 
YES : Erase the diagnostic trouble code memory, and check 

the diagnostic trouble code. If DTC B1438 or B1439 
sets, replace the SRS-ECU (Refer to 

P.52B-365

). 

Then go to Step 5.

NO :  Replace the harness wires between SRS-ECU 

connector C-122 and side impact sensor (LH) 
connector D-21. Then go to Step 5.

STEP 5. 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 B1438 or B1439 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

AC305250

CONNECTOR: D-21

AD

FRONT SEAT BELT

HARNESS SIDE
CONNECTOR
(REAR VIEW)

2

1

AC305412

AB

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

SRS AIR BAG DIAGNOSIS

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SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-184

DTC B1460: Seat Belt Pre-Tensioner (RH) (Squib) System Fault 1 (Short Circuit between Terminals of 
the Squib Circuit)

CAUTION

If DTC B1460 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 passenger’s seat 
belt pre-tensioner (squib).

.

TROUBLESHOOTING HITS

• Improper engaged connector or defective short 

spring*

• Short circuit between the passenger's seat belt 

pre-tensioner (squib) circuit terminals

• Damaged connector(s)

• Malfunction of the SRS-ECU

.

SEAT BELT
PRETENSIONER
(RH)

AIR BAG DRIVE CIRCUIT

SRS-ECU

CONNECTOR
LOCK SWITCH

CONNECTOR
LOCK SWITCH

: CONNECTOR CONNECTED: ON

  CONNECTOR DISCONNECTED: OFF

Passenger's (Front) Seat Belt Pre-Tensioner (Squib) Circuit

AC305362

CONNECTOR: C-120

C-120 (Y)

AC

SRS-ECU

AC307915 AB

CONNECTOR: D-33

D-33 (B)

FORWARD

CENTER 
PILLAR