Mitsubishi Galant 9G. Manual — part 1455

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-230

DTC B1473: Seat Belt Pre-Tensioner (LH) (Squib) System Fault for Ground Circuit (Short-Circuited to
Ground)

CAUTION

If DTC B1473 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

• Damaged wiring harnesses or connectors

• Short to the ground in the driver's seat belt

pre-tensioner (squib) harness

• 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-231

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)

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-232

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 Use Troubleshooting/Inspection
Service Points

− How to Cope with Intermittent

Malfunctions ).

AC305412

AB

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-233

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 check the

diagnostic trouble code.

Q: Is DTC B1473 set?

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

P.52B-380

. Then go to Step 6.

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