Code No.B1B22 Right curtain air bag module (squib) system (open circuit of squib circuit)
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If the diagnosis code B1B22 is set to SRS-ECU, be sure to diagnose the CAN bus line.
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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 as well as by the analogue G-sensor in SRS-ECU, the electric current is supplied from SRS-ECU to the curtain air bag module (squib) of impacted side.
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The code is set when the open circuit occurs to the SRS-ECU curtain air bag module (squib) circuit.
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- Open circuit to the curtain air bag module (squib) circuit
- Damaged connector(s)
- Malfunction of SRS-ECU
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STEP 1. M.U.T.-III CAN bus diagnostics.
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Use M.U.T.-III to diagnose the CAN bus lines.
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Q.
Is the check result normal?
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 Go to Step 2.
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 Repair the CAN bus line (Refer to GROUP 54C - Troubleshooting  ).
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STEP 2. Check whether the diagnosis code is reset.
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(1)Connect the negative battery terminal.
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(2)After erasing the diagnosis code memory, check the diagnosis code again.
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(3)Disconnect the negative battery terminal.
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Q.
Is the diagnosis code No. B1B22 set?
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Go to Step 3.
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Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction ).
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STEP 3. Diagnosis check by dummy resistor connection.
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(1)Check that the negative battery terminal is disconnected. If the negative battery terminal is connected, disconnect it.
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(2)Disconnect the D-11 intermediate connector (connection between curtain air bag harness and floor wiring harness).
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(3)Connect special tool dummy resistor (MB991865) to special tool resistor harness (MB991866).
(4)
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Do not insert a probe directly into the terminal from the connector front side as the connector contact pressure may be weakened.
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Insert the probe of resistor harness, to which the dummy resistor is installed, from the back of D-11 intermediate connector (floor wiring harness side).
(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. B1B22 set?
Go to Step 4.
Go to Step 5.
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STEP 4. Resistance measurement at the C-121 SRS-ECU connector and the D-11 intermediate connector.
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(1)Check that the negative battery terminal is disconnected. If the negative battery terminal is connected, disconnect it.
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(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-121 SRS-ECU connector.
(3)Disconnect the D-11 intermediate connector (connection between curtain air bag harness and floor wiring harness).
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(4)
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The short spring may not be released due to the insufficient insertion. Therefore, insert the insulator for 4 mm or more.
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Insert an insulator (width: 3 mm, thickness: 0.5 mm) such as cable tie between the terminal No. 39 and 40, and then release the short spring.
(5)
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Do not insert a probe directly into the terminal of D-11 intermediate connector from the connector front side as the connector contact pressure may be weakened.
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Check the continuity between the C-121 harness side connector terminal No. 39 and the D-11 intermediate connector (floor wiring harness side) terminal No. 2.
(6)Check the continuity between the C-121 harness side connector terminal No. 40 and the D-11 intermediate connector (floor wiring harness side) terminal No. 1.
OK: Continuity (less than 2 Ω)
Q.
Is the check result normal?
Go to Step 6.
Repair the wiring harness between the C-121 harness side connector terminal No. 39/40 and the D-11 intermediate connector (floor harness side) terminal No. 2/1.
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STEP 5. Resistance measurement between the D-11 intermediate connector terminal No. 1/2 and the F-06 curtain air bag module harness side connector terminal No. 1/2.
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(1)Check that the negative battery terminal is disconnected. If the negative battery terminal is connected, disconnect it.
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(2)Disconnect the D-11 intermediate connector (connection between curtain air bag harness and floor wiring harness).
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(3)Use the flat-tipped screwdriver to pull out the locking button of harness side connector. After releasing the lock, disconnect the F-06 harness side connector.
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(4)Connect special tool resister harness (MB991884) to the removed F-06 harness side connector.
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(5)Because the short spring is installed to the D-11 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.
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(6)
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Do not insert a probe directly into the terminal of D-11 intermediate connector from the connector front side as the connector contact pressure may be weakened.
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Check the continuity between the D-11 intermediate connector (curtain air bag harness side) terminal No. 1 and the resistor harness connector terminal No. 2.
(7)Check the continuity between the D-11 intermediate connector (curtain air bag harness side) terminal No. 2 and the resistor harness connector terminal No. 1.
OK: Continuity (less than 2 Ω)
Q.
Is the check result normal?
Replace the curtain air bag module (squib) (Refer to ).
Repair the wiring harness.
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STEP 6. Check whether the diagnosis code is reset.
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Q.
Is the diagnosis code No. B1B22 set?
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Replace SRS-ECU (Refer to ).
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Intermittent Malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction ).
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