Code No.B1431: Side-Airbag Module (LH) (Squib) System Fault 2 (Open in the
Squib Circuit)
![](../../../img/52/W4X52X005A00ENG.png)
![](../../../img/52/W4X52X024A00ENG.png)
caution |
If diagnosis code B1431 is set in the combination
meter, always diagnose the CAN bus lines.
|
OPERATION
- The SRS-ECU judges how severe a collision is by detecting signals from
the left and right side impact sensors. If the impact is over a
predetermined level, the SRS-ECU sends an ignition signal. At this time, if
the side-airbag safing G-sensor is on, the SRS side-airbag will
inflate.
- The ignition signal is input to the side-airbag module to inflate the
side-airbag.
DIAGNOSIS CODE SET CONDITIONS
This diagnosis code is set if there
is abnormal resistance between the input terminals of the side-airbag module
(LH) (squib).
PROBABLE CAUSES
- Open circuit in the side-airbag module (squib) (LH) circuit
- Improper connector contact
- Malfunction of the SRS-ECU
|
STEP 1. M.U.T.-III CAN bus diagnostics
|
|
Use the M.U.T.-III to diagnose the CAN bus
lines.
|
|
Q.
Is the check result normal?
|
|
Go to Step 2 .
|
|
|
|
Repair
the CAN bus lines (Refer to GROUP 54F, 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?
|
|
Go to Step 3 .
|
|
|
|
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 side-airbag module (LH) (M.U.T.-III diagnosis
code).
|
|
(1)Disconnect the negative battery terminal.
|
![](../../../img/52/AC303521AD00ENG.png)
|
(2)Disconnect the side-airbag module (LH)
connector D-22.
|
![](../../../img/52/AC006042BY00ENG.png)
|
(3)Connect special tool dummy resistor
(MB991865) to special tool resistor harness (MB991866). (4)
caution |
Do not insert a test probe into the terminal from
its front side directly, as the connector contact pressure may be
weakened.
|
Insert special tool MB991866 into the D-22 harness side connector
by backprobing. (5)Connect the negative battery terminal. (6)Erase
diagnosis code memory, and then check the diagnosis code.
Q.
Is diagnosis code B1431 set?
Go to Step 4 .
Replace the frame assembly of the
front seat (LH) (Refer to GROUP 52A, Front Seat ).
|
|
STEP 4. Resistance measurement between the SRS-ECU connector C-120
(terminal No.9 and 10) and the side-airbag module (LH) connector D-22
(terminal No.1 and 2).
|
![](../../../img/52/AC311438AE00ENG.png)
|
(1)Disconnect SRS-ECU connector C-120.
|
![](../../../img/52/AC303521AD00ENG.png)
|
(2)Disconnect side-airbag module (LH) connector
D-22.
|
![](../../../img/52/AC308176AG00ENG.png)
![](../../../img/52/AC313660AB00ENG.png)
|
(3)
caution |
Do not insert a test probe into the terminal from
its front side directly, as the connector contact pressure may be
weakened.
|
Check for continuity between the following
terminals. <LH drive vehicles>
- SRS-ECU connector C-120 (terminal No.9) and the side-airbag module
(LH) connector D-22 (terminal No.1)
- SRS-ECU connector C-120 (terminal No.10) and the side-airbag module
(LH) connector D-22 (terminal No.2)
<RH drive vehicles>
- SRS-ECU connector C-120 (terminal No.9) and the side-airbag module
(LH) connector D-22 (terminal No.2)
- SRS-ECU connector C-120 (terminal No.10) and the side-airbag module
(LH) connector D-22 (terminal No.1)
OK: Less than 2 Ω
Q.
Are the check results normal?
Go to Step 5 .
Repair the harness wires between
SRS-ECU connector C-120 (terminal No.9 and 10) and side-airbag module (LH)
connector D-22 (terminal No.1 and 2).
|
|
STEP 5.Check whether the diagnosis code is reset.
|
|
Q.
Is diagnosis code B1431 set?
|
|
Replace the SRS-ECU (Refer to ).
|
|
|
|
An
intermittent malfunction is suspected (Refer to GROUP 00, How to Use
Troubleshooting/Inspection Service Points ).
|
|
|