Mitsubishi Galant 9G. Manual — part 1422
SRS AIR BAG DIAGNOSIS
TSB Revision
SUPPLEMENTAL RESTRAINT SYSTEM (SRS)
52B-98
DTC B1412: Passenger’s (Front) Air Bag Module (1st Squib) System Fault for Power Supply Circuit
(Short-Circuited to Power Supply)
DTC B1492: Passenger’s (Front) Air Bag Module (2nd Squib) System Fault for Power Supply Circuit
(Short-Circuited to Power Supply)
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-99
CAUTION
If DTC B1412 <1st squib> or B1492 <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 air
bag module (squib). However, if no DTC resets, the
SRS warning light will be switched off (DTC will be
retained).
.
TROUBLESHOOTING HINTS
• Damaged harness wires and connectors
• Short to the power supply in the passenger's air
bag module (squib) harness
• Malfunction of the SRS-ECU
.
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
AC305362
CONNECTOR: C-121
C-121 (Y)
AD
SRS-ECU
SRS AIR BAG DIAGNOSIS
TSB Revision
SUPPLEMENTAL RESTRAINT SYSTEM (SRS)
52B-100
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,
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
AC305412
AB
MB991910
DATA LINK
CONNECTOR
MB991824
MB991827
SRS AIR BAG DIAGNOSIS
TSB Revision
SUPPLEMENTAL RESTRAINT SYSTEM (SRS)
52B-101
STEP 3. Check the passenger's air bag module. (Using
scan tool MB991958, read the diagnostic trouble code.)
(1) Disconnect the negative battery terminal.
(2) Disconnect the passenger’s air bag module connector
C-110.
(3) Slide the outer housing of the clock spring side of
passenger’s air bag module connector C-110 in the arrow
direction shown, and disconnect the connector.
(4) Connect special tool MB991865 to special tool MB991866.
CAUTION
Do not insert a test probe into the terminal from its front
side directly, as the connector contact pressure may be
weakened.
(5) Insert special tool MB991866 into the harness side
connector C-110 (terminal No.1 and 2 <1st squib> or
terminal No.3 and 4 <2nd squib>) by backprobing.
(6) Connect the negative battery terminal.
(7) Erase the diagnostic trouble code memory, and check the
diagnostic trouble code.
Q: Is DTC B1412 <1st squib> B1492 <2nd squib> set?
YES : Go to Step 4.
NO : Replace the passenger's air bag module (Refer to
AC307137AC
C-110 (Y)
FRONT DECK
CROSSMEMBER
CONNECTOR: C-110
HARNESS SIDE
CONNECTOR
(REAR VIEW)
AC306561AD
OUTER HOUSING OF THE PASSENGER'S
AIR BAG MODULE CONNECTOR C-110
AC306760AB
MB991865 (DUMMY
RESISTOR: 3
Ω
)
MB991866
(RESISTOR HARNESS)
C-110 HARNESS
CONNECTOR
C-110
PASSENGER'S
AIR BAG MODULE
CONNECTOR
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