Mitsubishi Grandis. Manual — part 1000
TROUBLESHOOTING
SUPPLEMENTAL RESTRAINT SYSTEM (SRS)
52B-52
YES :
Erase the diagnosis code memory, and
check the diagnosis code. If diagnosis code
B1411 <1st squib> or B1491 <2nd squib>
set, replace the SRS-ECU. (Refer to
NO :
Replace the harness wires between
SRS-ECU connector C-119 and
passenger’s air bag module connector
C-108. Then go to Step 5.
STEP 5. Check whether the diagnosis code is
reset.
Q: Is diagnosis code B1411 <1st squib> or B1491
<2nd squib> set?
YES :
Return to Step 1.
NO :
The procedure is complete.
Code No.B1412: Passenger’s (Front) Air Bag Module (1st Squib) System Fault for Earth Circuit
(Short-Circuited to Earth)
Code No.B1492: Passenger’s (Front) Air Bag Module (2nd Squib) System Fault for Earth Circuit
(Short-Circuited to Earth)
AIR BAG MODULE
(SQUIB)
(PASSENGER'S SIDE)
SRS-ECU
CONNECTOR
LOCK SWITCH
Wire colour code
B : Black LG : Light green G : Green L : Blue W : White Y : Yellow SB : Sky blue
BR : Brown O : Orange GR : Gray R : Red P : Pink V : Violet
: CONNECTOR
CONNECTED: ON
CONNECTOR
DISCONNECTED: OFF
NOTE
Passenger's (Front) Air Bag Module (1st Squib and 2nd Squib) Circuit
TROUBLESHOOTING
SUPPLEMENTAL RESTRAINT SYSTEM (SRS)
52B-53
CAUTION
If diagnosis code B1412 <1st squib> or B1492
<2nd squib> is set in the SRS-ECU, always
diagnose the CAN main bus line.
OPERATION
• The SRS-ECU judges how severe a collision is
by detecting signals from the front impact sensors
and the front air bag analogue 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.
DIAGNOSIS CODE SET CONDITIONS
This diagnosis code is set if there is abnormal
resistance between the input terminals of the
passenger's air bag module (squib). However, if no
diagnosis code resets, the SRS warning lamp will be
switched off (diagnosis code will be retained).
PROBABLE CAUSES
• Damaged harness wires and connectors
• Short to the earth in the passenger's air bag
module (squib) harness
• Malfunction of the SRS-ECU
DIAGNOSIS PROCEDURE
STEP 1. MUT-III CAN bus diagnostics
Use the MUT-III to diagnose the CAN bus lines.
Q: Is the check result normal?
YES :
Go to Step 2.
NO :
Repair the CAN bus line (Refer to GROUP
54D, Diagnosis
STEP 2. Check whether the diagnosis code is
reset.
Check again if the diagnosis code is set.
(1) Erase the diagnosis code.
(2) Ignition: LOCK (OFF) position to ON
(3) On completion, check that the diagnosis code is
not reset.
Q: Is the diagnosis code 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 Cope with
Intermittent Malfunction
STEP 3. Check the passenger's air bag module.
(MUT-III diagnosis code.)
(1) Disconnect the negative battery terminal.
(2) Disconnect the passenger’s air bag module
connector C-108.
(3) Slide the outer housing of the clock spring side of
passenger’s air bag module connector C-108 in
the arrow direction shown, and disconnect the
connector.
(4) Connect special tool dummy resistor (MB991865)
AC311373AC
C-108 (Y)
Connector: C-108 <LHD>
Harness side
(front view)
AC311375 AB
C-108 (Y)
Connector: C-108 <RHD>
Harness side
(front view)
AC306561AF
OUTER HOUSING OF THE PASSENGER'S
AIR BAG MODULE CONNECTOR C-09
AC306760AC
MB991865 (DUMMY
RESISTOR: 3
Ω)
MB991866
(RESISTOR HARNESS)
C-09 HARNESS
CONNECTOR
C-09
PASSENGER'S
AIR BAG MODULE
CONNECTOR
TROUBLESHOOTING
SUPPLEMENTAL RESTRAINT SYSTEM (SRS)
52B-54
to special tool resistor harness (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-108 (terminal No.1 and 2 <1st
squib> or terminal No.3 and 4 <2nd squib>) by
backprobing.
(6) Connect the negative battery terminal.
CAUTION
Always diagnosis code B1491 is set when
checking diagnosis code B1412. This is because
the second side terminal is isolated when
checking it,diagnosis code B1492 is set but this
is not a fault. In addition, always diagnosis code
B1411 is set when checking diagnosis code
B1492 because the first side terminal is isolated.
(7) Erase the diagnosis code memory, and check the
diagnosis code.
Q: Is the checked diagnosis code set?
YES :
Go to Step 4.
NO :
Replace the passenger's air bag module.
(Refer to
STEP 4. Check the passenger's air bag module
circuit. Resistance measurement at the SRS-ECU
connector C-119.
(1) Disconnect SRS-ECU connector C-119.
DANGER
To prevent the air bag from deploying
unintentionally, disconnect the passenger’s
air bag module connector C-108 to short the
squib circuit.
(2) Disconnect the passenger's air bag module
AC311438 AD
C-119 (Y)
Connector: C-119
Harness side
(front view)
AC311373AC
C-108 (Y)
Connector: C-108 <LHD>
Harness side
(front view)
AC311375 AB
C-108 (Y)
Connector: C-108 <RHD>
Harness side
(front view)
TROUBLESHOOTING
SUPPLEMENTAL RESTRAINT SYSTEM (SRS)
52B-55
connector C-108.
CAUTION
Do not insert a test probe into the terminal from
its front side directly, as the connector contact
pressure may be weakened.
(3) Check for continuity between C-119 harness side
connector terminals 27 and 28 <1st squib> or 30
and 31 <2nd squib>, and body earth.
OK: Open circuit
Q: Is the check result normal?
YES :
Erase the diagnosis code memory, and
check the diagnosis code. If diagnosis code
B1412 <1st squib> B1492 <2nd squib>
sets, replace the SRS-ECU. (Refer to
NO :
Replace the harness wires between
SRS-ECU connector C-119 and
passenger's air bag module connector
C-108. Then go to Step 5.
STEP 5. Check whether the diagnosis code is
reset.
Q: Is diagnosis code B1412 <1st squib> B1492 <2nd
squib> set?
YES :
Return to Step 1.
NO :
The procedure is complete.
AC301592
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-119 Harness side
connector (rear view)
<1st squib>
AE
AC308154
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-119 Harness side
connector (rear view)
<2nd squib>
AD
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