AIRBAG SYSTEM, Diagnostic DTC:B1925/78, B1926/78, B1927/78, B1928/78

DTC Code DTC Name
B1925/78 Short in Rear Pretensioner Squib LH Circuit
B1926/78 Open in Rear Pretensioner Squib LH Circuit
B1927/78 Short to GND in Rear Pretensioner Squib LH Circuit
B1928/78 Short to B+ in Rear Pretensioner Squib LH Circuit

DESCRIPTION

The rear pretensioner LH circuit consists of the airbag ECU assembly and rear No. 1 seat outer belt assembly LH.

This circuit instructs the SRS to deploy when deployment conditions are met.

These DTCs are stored when a malfunction is detected in the rear pretensioner LH circuit.

DTC No. Detection Item DTC Detection Condition Trouble Area
B1925/78 Short in Rear Pretensioner Squib LH Circuit

One of the following conditions is met:


  • The airbag ECU assembly detects a line short circuit signal 5 times in the rear pretensioner LH circuit during the primary check.

  • A rear No. 1 seat outer belt assembly LH malfunction.

  • An airbag ECU assembly malfunction.

  • No. 2 floor wire

  • Rear No. 1 seat outer belt assembly LH

  • Airbag ECU assembly
B1926/78 Open in Rear Pretensioner Squib LH Circuit

One of the following conditions is met:


  • The airbag ECU assembly detects an open circuit signal in the rear pretensioner LH circuit for 2 seconds.

  • A rear No. 1 seat outer belt assembly LH malfunction.

  • An airbag ECU assembly malfunction.

  • No. 2 floor wire

  • Rear No. 1 seat outer belt assembly LH

  • Airbag ECU assembly
B1927/78 Short to GND in Rear Pretensioner Squib LH Circuit

One of the following conditions is met:


  • The airbag ECU assembly detects a short circuit to ground signal in the rear pretensioner LH circuit for 0.5 seconds.

  • A rear No. 1 seat outer belt assembly LH malfunction.

  • An airbag ECU assembly malfunction.

  • No. 2 floor wire

  • Rear No. 1 seat outer belt assembly LH

  • Airbag ECU assembly
B1928/78 Short to B+ in Rear Pretensioner Squib LH Circuit

One of the following conditions is met:


  • The airbag ECU assembly detects a short circuit to B+ signal in the rear pretensioner LH circuit for 0.5 seconds.

  • A rear No. 1 seat outer belt assembly LH malfunction.

  • An airbag ECU assembly malfunction.

  • No. 2 floor wire

  • Rear No. 1 seat outer belt assembly LH

  • Airbag ECU assembly

WIRING DIAGRAM

B002K5YE01
*a Rear No. 1 Seat Outer Belt Assembly LH
*b Airbag ECU Assembly

CAUTION / NOTICE / HINT

Note


  • After turning the power switch off, waiting time may be required before disconnecting the cable from the negative (-) auxiliary battery terminal. Therefore, make sure to read the disconnecting the cable from the negative (-) auxiliary battery terminal notices before proceeding with work.

    Click here

  • When disconnecting the cable from the negative (-) auxiliary battery terminal while performing repairs, some systems need to be initialized after the cable is reconnected.

    Click here

  • After replacing the airbag ECU assembly, refer to initialization.

    Click here

Tech Tips

To perform the simulation method, enter check mode (signal check) with the GTS (Click here ), and then wiggle each connector of the airbag system or drive the vehicle on various types of road Click here.

PROCEDURE


  1. CHECK REAR NO. 1 SEAT OUTER BELT ASSEMBLY LH


    1. B002J0DC12
      *1 Rear No. 1 Seat Outer Belt Assembly LH
      *2 Airbag ECU Assembly
      *3 Connector C
      *4 SST
      *a

      Front view of wire harness connector

      (to Rear No. 1 Seat Outer Belt Assembly LH)

      Turn the power switch off.

    2. Disconnect the cable from the negative (-) auxiliary battery terminal, and wait for at least 90 seconds.

    3. Disconnect the connector from the rear No. 1 seat outer belt assembly LH.

    4. Connect the white wire side of SST (resistance: 2.1 Ω) to connector C.

      CAUTION:

      Never connect the tester to the rear No. 1 seat outer belt assembly LH for measurement, as this may lead to a serious injury due to airbag deployment.

      Note


      • Do not forcibly insert SST into the terminals of the connector when connecting SST.

      • Insert SST straight into the terminals of the connector.

      SST
      09843-18061

    5. Connect the cable to the negative (-) auxiliary battery terminal, and wait for at least 2 seconds.

    6. Turn the power switch on (IG), and wait for at least 60 seconds.

    7. Clear the DTCs.

      Click here


      Body Electrical > SRS Airbag > Clear DTCs

    8. Turn the power switch off.

    9. Turn the power switch on (IG), and wait for at least 60 seconds.

    10. Check for DTCs.

      Click here


      Body Electrical > SRS Airbag > Trouble Codes
      Result
      Proceed to
      DTC B1925/78, B1926/78, B1927/78 or B1928/78 is not output
      DTC B1925/78, B1926/78, B1927/78 or B1928/78 is output

      Tech Tips

      Codes other than DTC B1925/78, B1926/78, B1927/78 or B1928/78 may be output at this time, but they are not related to this check.

    11. Turn the power switch off.

    12. Disconnect the cable from the negative (-) auxiliary battery terminal, and wait for at least 90 seconds.

    13. Disconnect SST from connector C.


    DTC B1925/78, B1926/78, B1927/78 or B1928/78 is not output

    REPLACE REAR NO. 1 SEAT OUTER BELT ASSEMBLY LH Click here

    DTC B1925/78, B1926/78, B1927/78 or B1928/78 is output

  2. CHECK CONNECTORS


    1. Disconnect the connector from the airbag ECU assembly.

    2. B002IY0C03
      *1 Rear No. 1 Seat Outer Belt Assembly LH
      *2 No. 2 Floor Wire
      *3 Airbag ECU Assembly

      Check that the connectors (on the airbag ECU assembly side and rear No. 1 seat outer belt assembly LH side) are not damaged.

      OK
      The lock button is not disengaged, and the claw of the lock is not deformed or damaged.
      Result
      Proceed to
      OK
      NG

    NG

    REPLACE NO. 2 FLOOR WIRE

    OK

  3. CHECK NO. 2 FLOOR WIRE


    1. B002HYKC20
      *1 Rear No. 1 Seat Outer Belt Assembly LH
      *2 No. 2 Floor Wire
      *3 Airbag ECU Assembly
      *5 Connector C
      *a

      Front view of wire harness connector

      (to Rear No. 1 Seat Outer Belt Assembly LH)

      Connect the cable to the negative (-) auxiliary battery terminal, and wait for at least 2 seconds.

    2. Turn the power switch on (IG).

    3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      Q5-1 (RL-) - Body ground Power switch on (IG) Below 1 V
      Q5-2 (RL+) - Body ground Power switch on (IG) Below 1 V

    4. Turn the power switch off.

    5. Disconnect the cable from the negative (-) auxiliary battery terminal, and wait for at least 90 seconds.

    6. Measure the resistance according to the value(s) in the table below.

      Standard Resistance
      Tester Connection Condition Specified Condition
      Q5-1 (RL-) - Q5-2 (RL+) Always Below 1 Ω

    7. Release the activation prevention mechanism built into connector B.

      Click here

    8. Measure the resistance according to the value(s) in the table below.

      Standard Resistance
      Tester Connection Condition Specified Condition
      Q5-1 (RL-) - Q5-2 (RL+) Always 1 MΩ or higher

    9. Restore the released activation prevention mechanism of connector B to its original condition.

    10. Measure the resistance according to the value(s) in the table below.

      Standard Resistance
      Tester Connection Condition Specified Condition
      Q5-1 (RL-) - Body ground Always 1 MΩ or higher
      Q5-2 (RL+) - Body ground Always 1 MΩ or higher
      Result
      Proceed to
      OK
      NG

    NG

    REPLACE NO. 2 FLOOR WIRE

    OK

  4. CHECK DTC


    1. B002I2LC12
      *1 Rear No. 1 Seat Outer Belt Assembly LH
      *2 Airbag ECU Assembly

      Connect the connectors to the rear No. 1 seat outer belt assembly LH and airbag ECU assembly.

    2. Connect the cable to the negative (-) auxiliary battery terminal, and wait for at least 2 seconds.

    3. Turn the power switch on (IG), and wait for at least 60 seconds.

    4. Clear the DTCs.

      Click here


      Body Electrical > SRS Airbag > Clear DTCs

    5. Turn the power switch off.

    6. Turn the power switch on (IG), and wait for at least 60 seconds.

    7. Check for DTCs.

      Click here


      Body Electrical > SRS Airbag > Trouble Codes
      Result
      Proceed to
      DTC B1925/78, B1926/78, B1927/78 or B1928/78 is not output
      DTC B1925/78, B1926/78, B1927/78 or B1928/78 is output

      Tech Tips

      Codes other than DTC B1925/78, B1926/78, B1927/78 and B1928/78 may be output at this time, but they are not related to this check.


    DTC B1925/78, B1926/78, B1927/78 or B1928/78 is not output

    USE SIMULATION METHOD TO CHECK Click here

    DTC B1925/78, B1926/78, B1927/78 or B1928/78 is output

    REPLACE AIRBAG ECU ASSEMBLY Click here