Mitsubishi Galant 9G. Manual - part 1418

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-82

DTC B1410: Passenger’s (Front) Air Bag Module (1st Squib) System Fault 1 (Short Circuit between
Terminals of the Squib Circuit)
DTC B1490: Passenger’s (Front) Air Bag Module (2nd Squib) System Fault 1 (Short Circuit between
Terminals of the Squib Circuit)

Passenger's (Front) Air Bag Module (1st Squid and 2nd Squib) Circuit

AIR BAG MODULE
(SQUIB) (PASSENGER'S SIDE)

AIR BAG DRIVE CIRCUIT

: CONNECTOR CONNECTED
: ON
CONNECTOR DICONNECTED
: OFF

SRS-ECU

CONNECTOR
LOCK SWITCH

NOTE

AC305233 AO

CONNECTOR: C-22

C-22 (Y)

AC307137AD

C-110 (Y)

FRONT DECK
CROSSMEMBER

CONNECTOR: C-110

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-83

CAUTION

If DTC B1410 <1st squib> or B1490 <2nd squib>
is set in the SRS-ECU, always diagnose 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 SRS
air bag will inflate.

• The ignition signal is input to the air bag module

via the clock spring to inflate the air bag.

DTC SET CONDITIONS

This DTC is set if there is abnormal resistance
between the input terminals of the passenger's side
air bag module (squib). However, if no DTC reset,
the SRS warning light will be switched off (DTC will
be retained).

TROUBLESHOOTING HINTS

• Improper engaged connector or defective short

spring*

• Short circuit between the passenger's air bag

module (squib) circuit terminals

• Damaged connector(s)

• Malfunction of the SRS-ECU

NOTE: *: The squib circuit connectors integrate a
"short" spring (which prevents the air bag from
deploying unintentionally due to static electricity by
shorting the positive wire to the ground wire in the
squib circuit when the connectors are disconnected)
(Refer to

P.52B-3

). Therefore, if connector C-121,

C-22 or C-110 is damaged or improperly engaged,
the short spring may not be released when the con-
nector 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 (Vehicles with CAN

Communication System)

• MB991865: Dummy resister

• MB991866: Resister harness

AC305362

CONNECTOR: C-121

C-121 (Y)

SRS-ECU

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-84

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 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

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

AC305412

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-85

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 B1519 set?

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

STEP 4. Check SRS-ECU connector C-121.
Q: Is the connector correctly engaged?

YES : Go to Step 5.
NO : Engage the connector correctly. Then go to Step 9.

AC305412

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

AC305362

CONNECTOR: C-121

C-121 (Y)

SRS-ECU

C-121
HARNESS SIDE
CONNECTOR
(REAR VIEW)

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