Mitsubishi Galant (2004+). Manual — part 1536
SRS AIR BAG DIAGNOSIS
TSB Revision
SUPPLEMENTAL RESTRAINT SYSTEM (SRS)
52B-37
NOTE:
*1
: Electrically Erasable Programmable ROM
*2
: This DTC will remain in memory and the SRS warning light will be switched off when the system returns to
normal condition.
*3
: This DTC will remain in memory and the SRS warning light will be switched on even if the system returns
to normal condition.
*4
: This DTC will remain in memory when the front passenger's air bag is inactive condition in the event of an
impact.
*5
: This DTC cannot be erased by "Erase DTCs" function.
B1538
*3
Seat belt switch (LH) circuit (ground side) shorted (for COM
termnal)
B1539
*3
Seat belt switch (LH) circuit (power supply side) shorted (for
COM termnal)
B1540
*3
Occupant classification-ECU malfunction
B1541
*3
Occupant classification-ECU calibration malfunction
B1542
*3
Occupant classification sensor (S1) malfunction
B1543
*3
Occupant classification sensor (S2) malfunction
B1545
*3
Occupant classification-ECU communication error
B1546
*3
Occupant classification-ECU communication impossible
B1547
*4*5
Cut OFF for passenger’s front air bag
B1552
*5
Changing circuit shorted
B1553
*5
Changing circuit open
B1554
*5
SG BY-PASS circuit malfunction
B1555
*5
SG BY-PASS circuit (FET) open
B1556
*3
Seat slide sensor malfunction
B1557
*5
SRS-ECU ASIC
B1558
*3
Occupant classification-ECU ID-cord malfunction
U1073
*2
Bus-off
DIAGNOSTIC
TROUBLE CODE
NO.
INSPECTION ITEM
REFERENCE PAGE
SRS AIR BAG DIAGNOSIS
TSB Revision
SUPPLEMENTAL RESTRAINT SYSTEM (SRS)
52B-38
DIAGNOSTIC TROUBLE CODE PROCEDURES
DTC B1400: Driver’s Air Bag Module (1st Squib) System Fault 1 (Short Circuit between Terminals of
the Squib Circuit)
DTC B1480: Driver’s Air Bag Module (2nd Squib) System Fault 1 (Short Circuit between Terminals of
the Squib Circuit)
AIR BAG MODULE
(SQUIB)
(DRIVER'S SIDE)
CLOCK
SPRING
AIR BAG DRIVE CIRCUIT
SRS-ECU
: CONNECTOR LOCK SWITCH
CONNECTOR CONNECTED: ON
CONNECTOR DISCONNECTED: OFF
CONNECTOR
LOCK SWITCH
Driver's Air Bag Module (1st and 2nd Squib) Circuit
SRS AIR BAG DIAGNOSIS
TSB Revision
SUPPLEMENTAL RESTRAINT SYSTEM (SRS)
52B-39
CAUTION
If DTC B1400 <1st squib> or B1480 <2nd squib>
is set in the combination meter, always diagnose
the CAN bus lines.
.
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 driver's side air
bag module (squib). The most likely causes for
this code to be set are the followings:
• Short circuit in driver’s air bag module (squib)
or harness
• Short circuit in the clock spring
However, if no DTC reset, the SRS warning light will
be turned off (DTC will OK).
.
TROUBLESHOOTING HINTS
• Improper engaged connector or defective short
spring*
• Short circuit in the clock spring
• Short circuit between the driver'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
). Therefore, if connector C-121,
C-307 or C-305 is damaged or improperly engaged,
the short spring may not be released when the con-
nector is connected.
.
AC305233 AO
CONNECTOR: C-22
C-22 (Y)
AC305362
CONNECTOR: C-121
C-121 (Y)
AD
SRS-ECU
AC305235AP
C-307 (Y)
CONNECTORS: C-305, C-307
CLOCK
SPRING
C-305 (Y)
SRS AIR BAG DIAGNOSIS
TSB Revision
SUPPLEMENTAL RESTRAINT SYSTEM (SRS)
52B-40
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 resistor
• MB991866: Resister harness
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
."
(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,
AC305412
AB
MB991910
DATA LINK
CONNECTOR
MB991824
MB991827
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