CODE NO. B1B0A Passenger’s (front) air bag module (1st squib) system (open circuit of squib circuit)
CODE NO. B1B0E Passenger’s (front) air bag module (2nd squib) system (open circuit of squib circuit)













caution If the diagnosis code B1B0A (1st squib) or B1B0E (2nd squib) is set to SRS-ECU, be sure to diagnose the CAN bus line.

OPERATION


Only when the frontal impact exceeding the threshold is simultaneously detected (turned ON) by the front impact sensor as well as by the analogue G-sensor and safing G-sensor in SRS-ECU, the electric current is supplied from SRS-ECU to the driver’s and passenger’s (front) air bag modules (squibs).

TROUBLE JUDGMENT


The code is set when the open circuit occurs to the SRS-ECU passenger’s (front) air bag module (squib) circuit.

PROBABLE CAUSES



  • Open circuit in the passenger’s (front) air bag 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. M.U.T.-III diagnosis code.


(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. B1B0A or B1B0E 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 connector while sliding the C-12 wiring harness side connector to the direction of the arrow.

(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 C-12 harness side connector terminals Nos. 1 and 2 (1st squib) and Nos. 3 and 4 (2nd squib).
(5)Connect the negative battery terminal.
(6)
caution At the diagnosis code B1B0A check, always the diagnosis code B1B0E is set. The diagnosis code B1B0E is set because the 2nd side terminal is disconnected at the time of inspection, but this does not indicate any abnormality. Also, at the time of diagnosis code B1B0E check, always the diagnosis code B1B0A is set because the 1st side terminals are disconnected.
After erasing the diagnosis code memory, check the diagnosis code again.
(7)Disconnect the negative battery terminal.

Q. Is the diagnosis code No. B1B0A or B1B0E set?

Go to Step 4.

Replace the passenger’s (front) air bag module (squib) (Refer to ).

STEP 4. Resistance measurement at the C-32 SRS-ECU connector and the C-12 passenger’s (front) air bag 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-32 SRS-ECU connector.

(3)Disconnect the connector while sliding the C-12 wiring harness side connector to the direction of the arrow.


(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 terminals Nos. 7 and 8 (1st squib) and Nos. 11 and 12 (2nd squib), and then release the short spring.
(5)
caution Do not insert a probe directly into the terminal of C-12 harness side connector from the connector front side as the connector contact pressure may be weakened.
Take the measurements below at the C-32 and C-12 wiring harness side connectors.

  • Continuity between the C-32 SRS-ECU connector terminal No. 7 and the C-12 passenger’s (front) air bag module connector terminal No. 2 (1st squib)
  • Continuity between the C-32 SRS-ECU connector terminal No. 8 and the C-12 passenger’s (front) air bag module connector terminal No. 1 (1st squib)

  • Continuity between the C-32 SRS-ECU connector terminal No. 11 and the C-12 passenger’s (front) air bag module connector terminal No. 4 (2nd squib)
  • Continuity between the C-32 SRS-ECU connector terminal No. 12 and the C-12 passenger’s (front) air bag module connector terminal No. 3 (2nd squib)
OK: Continuity (less than 2 Ω)

Q. Is the check result normal?

Go to Step 5.

Repair the wiring harnesses between the C-12 passenger’s (front) air bag module connector terminal No. 1/2 and the C-32 SRS-ECU connector terminal No. 8/7 (1st squib), and between the C-12 passenger’s (front) air bag module connector terminal No. 3/4 and the C-32 SRS-ECU connector terminal No. 12/11 (2nd squib).

STEP 5. Check whether the diagnosis code is reset.


Q. Is the diagnosis code No. B1B0A or B1B0E 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 ).