CODE NO. B1C2A Left side-airbag module (squib) system (short circuit between squib terminals)
caution
If the diagnosis code B1C2A is set to SRS-ECU, be sure to diagnose the CAN bus line.
OPERATION
In case of side collision, when the impact exceeding the threshold is applied to the vehicle, and when the impact is simultaneously detected (turned ON) by the side impact sensor installed to the lower part of centre pillar as well as by the side-airbag safing G-sensor in SRS-ECU, the electric current is supplied from SRS-ECU to the side-airbag module (squib) of impacted side.
TROUBLE JUDGMENT
The code is set when the short circuit occurs to between the terminals of SRS-ECU side-airbag module (squib) circuit.
PROBABLE CAUSES
Damaged short spring *
Short circuit between terminals of side-airbag module (squib) circuit
Damaged connector(s)
Malfunction of SRS-ECU
note
*: The squib circuit connectors integrate a short spring (which prevents the air bags from being unintentionally deployed because of static electricity by shorting the positive wire to the earth wire in the squib circuit when the connectors are disconnected). Therefore, when the above codes are set, the short spring may not be released due to the damaged connector even when the connectors are connected.
DIAGNOSIS PROCEDURE
STEP 1. M.U.T.-III CAN bus diagnostics.
Use M.U.T.-III to diagnose the CAN bus lines.
Q.
Is the check result normal?
Go to Step 2.
Repair the CAN bus line (Refer to GROUP 54C - Troubleshooting ).
STEP 2. Check whether the diagnosis code is reset.
(1)Connect the negative battery terminal.
(2)After erasing the diagnosis code memory, check the diagnosis code again.
(3)Disconnect the negative battery terminal.
Q.
Is the diagnosis code No. B1C2A set?
Go to Step 3.
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction ).
STEP 3. Connector check: C-31 SRS-ECU, D-30 left side-airbag module.
(1)Check that the negative battery terminal is disconnected. If the negative battery terminal is connected, disconnect it.
(2)While pushing the part "A" indicated in the figure of the harness side connector, turn the lock lever to the direction of the arrow to release the lock lever. After disconnecting the C-31 SRS-ECU connector, connect it again. (3)After disconnecting the D-30 connector, connect the connector again. (4)Connect the negative battery terminal. (5)After erasing the diagnosis code memory, check the diagnosis code again. (6)Disconnect the negative battery terminal.
Q.
Is the diagnosis code No. B1C2A set?
Go to Step 4.
Repair the connector concerned.
STEP 4. Diagnosis check by dummy resistor connection.
(1)Check that the negative battery terminal is disconnected. If the negative battery terminal is connected, disconnect it.
(2)Disconnect the D-30 side-airbag module connector.
(3)Connect special tool dummy resistor (MB991865) to special tool resistor harness (MB991866). (4)
caution
Do not insert a probe directly into the terminal from the connector front side as the connector contact pressure may be weakened.
Insert the resistor harness probe from the back of D-30 harness side connector. (5)Connect the negative battery terminal. (6)After erasing the diagnosis code memory, check the diagnosis code again. (7)Disconnect the negative battery terminal.
Q.
Is the diagnosis code No. B1C2A set?
Go to Step 5.
Replace the seatback frame assembly (Refer to ).
STEP 5. Resistance measurement at the C-31 SRS-ECU connector.
(1)While pushing the part "A" indicated in the figure of the harness side connector, turn the lock lever to the direction of the arrow to release the lock lever, and disconnect the C-31 SRS-ECU connector. (2)
danger
To release the connector short spring in the following operations, disconnect this side-airbag module connector, and keep the squib circuit shorted.
Disconnect the D-30 side-airbag module connector.
(3)
caution
The short spring may not be released due to the insufficient insertion. Therefore, insert the insulator for 4 mm or more.
Insert an insulator (width: 3 mm, thickness: 0.5 mm) such as cable tie between the terminal 31/32 and the short spring, and then release the short spring. (4)Take the measurements below at the C-31 harness side connector.
Continuity between terminals 31 and 32
OK: No continuity
Q.
Is the check result normal?
Go to Step 6.
Repair the wiring harness between the D-30 side-airbag module connector terminal No. 1/2 and the C-31 SRS-ECU connector terminal No. 32/31.
STEP 6. Check whether the diagnosis code is reset.
Q.
Is the diagnosis code No. B1C2A set?
Replace SRS-ECU (Refer to ).
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction ).
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Go to Step 2.
Repair the CAN bus line (Refer to GROUP 54C - Troubleshooting 
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