Mitsubishi Galant 9G. Manual — part 1409
SRS AIR BAG DIAGNOSIS
TSB Revision
SUPPLEMENTAL RESTRAINT SYSTEM (SRS)
52B-46
CAUTION
Do not insert a test probe into the terminal from its front
side directly as the connector contact pressure may be
weakened.
(4) Check for continuity between C-26 harness side connector
terminals 36 and 37 <1st squib> or 33 and 34 <2nd squib>.
It should be open circuit.
Q: Does continuity exist?
YES : Erase the diagnostic trouble code memory, and check
the diagnostic trouble code. If DTC B1400 <1st
squib> or B1481 <2nd squib> set, replace the
SRS-ECU (Refer to
NO : Go to Step 9.
STEP 9. Check the harness for short circuit between
SRS-ECU connector C-121 (terminal No.36 and 37 <1st
squib> or No.33 and 34 <2nd squib>) and clock spring
connector C-307 (terminal No.13 and 14 <1st squib> or
No.11 and 12 <2nd squib>).
AC301581
42
31
38
27
21
41
28
39
22
30
25
47
36
33
44
34
45
37
48
26
29
23
40
32
43
35
46
24
B
A
C-121 HARNESS SIDE
CONNECTOR (REAR VIEW)
<1ST SQUIB>
AC
AC308145
42
31
38
27
21
41
28
39
22
30
25
47
36
33
44
34
45
37
48
26
29
23
40
32
43
35
46
24
B
A
C-121 HARNESS SIDE
CONNECTOR (REAR VIEW)
<2ND SQUIB>
AB
AC305362
CONNECTOR: C-121
C-121 (Y)
AH
SRS-ECU
C-121
HARNESS SIDE
CONNECTOR
(REAR VIEW)
42
31
38
27
21
41
28
39
22
30
25
47
36
33
44
34
45
37
48
26
29
23
40
32
43
35
46
24
B
A
AC305235AK
C-307 (Y)
CONNECTOR: C-307
C-307 HARNESS
SIDE CONNECTOR
CLOCK
SPRING
11
12
13
14
SRS AIR BAG DIAGNOSIS
TSB Revision
SUPPLEMENTAL RESTRAINT SYSTEM (SRS)
52B-47
NOTE: After inspecting intermediate connector C-22 inspect
the wiring harness. If the intermediate connector C-22 is dam-
aged, repair or replace it.
Q: Are harness wires between SRS-ECU connector C-121
(terminal No.36 and 37 <1st squib> or No.33 and 34
<2nd squib>) and clock spring connector C-307
(terminal No.13 and 14 <1st squib> or No.11 and 12 <2nd
squib>) in good condition?
YES : Go to Step 10.
NO : Replace the harness wires between SRS-ECU
connector C-121 and clock spring connector C-307.
Then go to Step 10.
STEP 10. 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 B1400 <1st squib> or B1480 <2nd squib> set?
YES : Return to Step 1.
NO : The procedure is complete.
AC305233
C-22 (Y)
CO
CONNECTOR: C-22
AC305412
AB
MB991910
DATA LINK
CONNECTOR
MB991824
MB991827
SRS AIR BAG DIAGNOSIS
TSB Revision
SUPPLEMENTAL RESTRAINT SYSTEM (SRS)
52B-48
DTC B1401: Driver's Air Bag Module (1st Squib) System Fault 2 (Open in the Squib Circuit)
DTC B1481: Driver's Air Bag Module (2nd Squib) System Fault 2 (Open in the Squib Circuit)
Driver's Air Bag Module (1st and 2nd Squib) Circuit
AIR BAG MODULE
(SQUIB) (DRIVER'S SIDE)
CLOCK
SPRING
AIR BAG DRIVE CIRCUIT
SRS-ECU
CONNECTOR
LOCK SWITCH
: CONNECTOR LOCK SWITCH
CONNECTOR CONNECTED: ON
CONNECTOR DICONNECTED: OFF
AC305233 AO
CONNECTOR: C-22
C-22 (Y)
AC305362
CONNECTOR: C-121
C-121 (Y)
AD
SRS-ECU
SRS AIR BAG DIAGNOSIS
TSB Revision
SUPPLEMENTAL RESTRAINT SYSTEM (SRS)
52B-49
CAUTION
If DTC B1401 <1st squib> or B1481 <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 driver's side air
bag module (squib). The most likely causes for
this code to be set are the followings:
• Open circuit in the driver's air bag module
(squib) or harness
• Open circuit in the clock spring
• Malfunction of connector contact
However, if no DTC reset, the SRS warning light will
be switched off (DTC will be retained).
.
TROUBLESHOOTING HINTS
• Open circuit in the clock spring
• Open circuit due to improper neutral position of
the clock spring
• Open circuit in the driver's air bag module (squib)
circuit
• Disengaged driver's air bag module (squib) con-
nector
• Improper connector contact
• 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
AC305235AP
C-307 (Y)
CONNECTORS: C-305, C-307
CLOCK
SPRING
C-305 (Y)
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