CODE NO. B1C29 Left side-airbag module (squib) system (open circuit of squib circuit)













caution If the diagnosis code B1C29 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 open circuit occurs to the SRS-ECU side-airbag module (squib) circuit.

PROBABLE CAUSES



  • Open circuit to side-airbag module (squib) circuit
  • Poor contact of connector
  • Malfunction of SRS-ECU

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. B1C29 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. 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. B1C29 set?

Go to Step 4.

Replace the seatback frame assembly (Refer to ).

STEP 4. Resistance measurement at the C-31 SRS-ECU connector and the D-30 side-airbag module connector.


(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, and disconnect the C-31 SRS-ECU connector.
(3)Disconnect the D-30 side-airbag module connector.

(4)
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 No. 31 and 32, and then release the short spring.
(5)
caution Do not insert a test probe directly into the terminal of D-30 harness side connector from the connector front side as the connector contact pressure may be weakened.
Take the measurements below at the C-31 and D-30 harness side connectors.

  • Continuity between C-31 SRS-ECU connector terminal No. 31 and D-30 side-airbag module connector No. 2
  • Continuity between C-31 SRS-ECU connector terminal No. 32 and D-30 side-airbag module connector No. 1
OK: Continuity (less than 2 Ω)

Q. Is the check result normal?

Go to Step 5.

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 5. Check whether the diagnosis code is reset.


Q. Is the diagnosis code No. B1C29 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 ).