CODE NO. B1B23 Right curtain air bag module (squib) system (short circuit between squib circuit terminals)










caution If the diagnosis code B1B23 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 and quarter panel inner as well as by the side-airbag safing G-sensor in SRS-ECU, the ignition signal is sent from SRS-ECU to the curtain air bag module (squib) of impacted side.

TROUBLE JUDGMENT
The code is set when the short circuit occurs between the terminals of SRS-ECU curtain air bag module (squib) circuit.

PROBABLE CAUSES

  • Damaged short spring *
  • Short circuit between terminals of curtain air bag 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. B1B23 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-103 curtain air bag module, D-08 intermediate 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. After disconnecting the C-31 SRS-ECU connector, connect it again.

(3)After disconnecting the D-08 and D-103 harness side connectors, connect the connectors again. For the D-103 connector disconnection, use the flat-tipped screwdriver to pull out the harness side connector locking button. After releasing the lock, disconnect the connector.
(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. B1B23 set?

Go to Step 4.

Connector repair

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-08 intermediate connector (connection between curtain air bag harness and floor harness).

(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 probe of resistor harness, to which the dummy resister is installed, from the back of D-08 intermediate connector (floor harness side).
(5)Connect the negative battery terminal.
(6)After erasing the diagnosis code memory, check the diagnosis code again.

Q. Is the diagnosis code No. B1B23 set?

Go to Step 5.

Go to Step 6.

STEP 5. Resistance measurement at the C-31 SRS-ECU 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)
danger To release the SRS-ECU connector short spring in the following operations, disconnect this D-08 intermediate connector, and keep the squib circuit shorted.
Disconnect the D-08 intermediate connector (connection between curtain air bag harness and floor harness).

(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 39/40 and the short spring, and release the short spring.
(5)Check the continuity between the C-31 wiring harness side connector terminal No. 39 and No. 40.
OK: No continuity

Q. Is the check result normal?

Go to Step 7.

Repair the wiring harness.

STEP 6. Short circuit check between the D-103 curtain air bag module harness side connector and the D-08 intermediate harness.
(1)Check that the negative battery terminal is disconnected. If the negative battery terminal is connected, disconnect it.

(2)
danger To release the D-08 intermediate connector short spring in the following operations, disconnect the D-103 air bag module harness side connector beforehand, and keep the squib circuit shorted.
Use the flat-tipped screwdriver to pull out the locking button of harness side connector. After releasing the lock, disconnect the D-103 harness side connector.
(3)Disconnect the D-08 intermediate connector.

(4)Because the short spring is installed to the D-08 intermediate connector (curtain air bag harness side), insert an insulator (width: 3 mm, thickness: 0.5 mm) such as cable tie to the location shown in the figure, and release the short spring.
(5)
caution Do not insert a probe directly into the terminal from the connector front side as the connector contact pressure may be weakened.
Check the continuity between the D-08 intermediate connector (curtain air bag harness side) terminal No. 1 and No. 2.
OK: No continuity

Q. Is the check result normal?

Replace the curtain air bag module (Refer to ).

Repair the wiring harness.

STEP 7. Check whether the diagnosis code is reset.

Q. Is the diagnosis code No. B1B23 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 ).