AIRBAG SYSTEM, Diagnostic DTC:B1920/77, B1921/77, B1922/77, B1923/77

DTC Code DTC Name
B1920/77 Short in Rear Pretensioner Squib RH Circuit
B1921/77 Open in Rear Pretensioner Squib RH Circuit
B1922/77 Short to GND in Rear Pretensioner Squib RH Circuit
B1923/77 Short to B+ in Rear Pretensioner Squib RH Circuit

DESCRIPTION

The rear pretensioner squib RH circuit consists of the airbag ECU assembly and rear seat 3 point type outer belt assembly RH.

The airbag ECU assembly uses this circuit to deploy the pretensioner when deployment conditions are met.

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

DTC No. Detection Item DTC Detection Condition Trouble Area Test Mode / Check Mode
B1920/77 Short in Rear Pretensioner Squib RH Circuit

    Any of the following conditions is met:

  • The airbag ECU assembly detects a line short in the rear pretensioner squib RH circuit during primary check.

  • Rear pretensioner squib RH malfunction

  • Airbag ECU assembly malfunction

  • Floor wire

  • Rear pretensioner squib RH (Rear seat 3 point type outer belt assembly RH)

  • Airbag ECU assembly

 Applies to check mode
B1921/77 Open in Rear Pretensioner Squib RH Circuit

    Any of the following conditions is met:

  • The airbag ECU assembly detects an open in the rear pretensioner squib RH circuit.

  • Rear pretensioner squib RH malfunction

  • Airbag ECU assembly malfunction

  • Floor wire

  • Rear pretensioner squib RH (Rear seat 3 point type outer belt assembly RH)

  • Airbag ECU assembly

 Applies to check mode
B1922/77 Short to GND in Rear Pretensioner Squib RH Circuit

    Any of the following conditions is met:

  • The airbag ECU assembly detects a short to ground in the rear pretensioner squib RH circuit.

  • Rear pretensioner squib RH malfunction

  • Airbag ECU assembly malfunction

  • Floor wire

  • Rear pretensioner squib RH (Rear seat 3 point type outer belt assembly RH)

  • Airbag ECU assembly

 Applies to check mode
B1923/77 Short to B+ in Rear Pretensioner Squib RH Circuit

    Any of the following conditions is met:

  • The airbag ECU assembly detects a short to B+ in the rear pretensioner squib RH circuit.

  • Rear pretensioner squib RH malfunction

  • Airbag ECU assembly malfunction

  • Floor wire

  • Rear pretensioner squib RH (Rear seat 3 point type outer belt assembly RH)

  • Airbag ECU assembly

 Applies to check mode
DTC Detection Conditions: B1920/77
Vehicle Condition
Pattern 1 Pattern 2 Pattern 3
Diagnosis Condition - - - -
Malfunction Status The airbag ECU assembly detects a line short in the rear pretensioner squib RH circuit during primary check ○ - -
Rear pretensioner squib RH malfunction - ○ -
Airbag ECU assembly malfunction - - ○
Detection Time - - -
Number of Trips 1 trip 1 trip 1 trip

Tech Tips

DTC will be output when conditions for either of the patterns in the table above are met.

DTC Detection Conditions: B1921/77
Vehicle Condition
Pattern 1 Pattern 2 Pattern 3
Diagnosis Condition - - - -
Malfunction Status The airbag ECU assembly detects an open in the rear pretensioner squib RH circuit ○ - -
Rear pretensioner squib RH malfunction - ○ -
Airbag ECU assembly malfunction - - ○
Detection Time - - -
Number of Trips 1 trip 1 trip 1 trip

Tech Tips

DTC will be output when conditions for either of the patterns in the table above are met.

DTC Detection Conditions: B1922/77
Vehicle Condition
Pattern 1 Pattern 2 Pattern 3
Diagnosis Condition - - - -
Malfunction Status The airbag ECU assembly detects a short to ground in the rear pretensioner squib RH circuit ○ - -
Rear pretensioner squib RH malfunction - ○ -
Airbag ECU assembly malfunction - - ○
Detection Time - - -
Number of Trips 1 trip 1 trip 1 trip

Tech Tips

DTC will be output when conditions for either of the patterns in the table above are met.

DTC Detection Conditions: B1923/77
Vehicle Condition
Pattern 1 Pattern 2 Pattern 3
Diagnosis Condition - - - -
Malfunction Status The airbag ECU assembly detects a short to B+ in the rear pretensioner squib RH circuit ○ - -
Rear pretensioner squib RH malfunction - ○ -
Airbag ECU assembly malfunction - - ○
Detection Time - - -
Number of Trips 1 trip 1 trip 1 trip

Tech Tips

DTC will be output when conditions for either of the patterns in the table above are met.

WIRING DIAGRAM

B002EM4E11
*a Rear Pretensioner Squib RH (Rear Seat 3 Point Type Outer Belt Assembly RH)
*b Airbag ECU Assembly

CAUTION / NOTICE / HINT

Note

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

Click here

Tech Tips


  • Perform the simulation method by selecting check mode (Signal Check) using the GTS.

    Click here

  • After selecting check mode (Signal Check), perform the simulation method by wiggling each connector of the airbag system or driving the vehicle on a city road or rough road.

    Click here

PROCEDURE


  1. CHECK CONNECTORS


    1. B002CE4C07
      *1 Rear Seat 3 Point Type Outer Belt Assembly RH
      *2 Airbag ECU Assembly
      *3 Floor Wire

      Turn the engine switch off.

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

    3. Check that the connectors are properly connected to the rear seat 3 point type outer belt assembly RH and airbag ECU assembly.

      OK
      The connectors are properly connected.

      Tech Tips

      If the connectors are not properly connected, reconnect the connectors and proceed to the next inspection.

    4. Disconnect the connectors from the rear seat 3 point type outer belt assembly RH and airbag ECU assembly.

    5. Check that the terminals of the connectors are not damaged.

      OK
      The terminals are not deformed or damaged.

    6. Check that the floor wire connector (on the rear seat 3 point type outer belt assembly RH side) is not damaged.

      OK
      The connector locking button is not disengaged, and the claw of the lock is not deformed or damaged.

    7. Check that the short spring for the floor wire with the activation prevention mechanism is not deformed or damaged.

      OK
      The short spring is not deformed or damaged.
      Result
      Proceed to
      OK
      NG

    NG

    REPLACE FLOOR WIRE

    OK

  2. CHECK REAR SEAT 3 POINT TYPE BELT ASSEMBLY OUTER RH


    1. B002ENJC16
      *1 Rear Seat 3 Point Type Outer Belt Assembly RH
      *2 Airbag ECU Assembly
      *a

      Front view of wire harness connector

      (to Rear Seat 3 Point Type Outer Belt Assembly RH)

      Connect the connector to the airbag ECU assembly.

    2. Connect SST (resistance 2.1 Ω) to connector C.

      CAUTION:

      Never connect a tester to the rear seat 3 point type outer belt assembly RH for measurement, as this may lead to a serious injury due to pretensioner deployment.

      B002CZK

      Note


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

      • Insert SST straight into the terminals of the connector.

      SST
      09843-18061

    3. Connect the cable to the negative (-) battery terminal.

    4. Clear the DTCs stored in memory.

      Click here


      Body Electrical > SRS Airbag > Clear DTCs

    5. Turn the engine switch off.

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

    7. Check for DTCs.

      Click here


      Body Electrical > SRS Airbag > Trouble Codes
      OK
      DTC B1920/77, B1921/77, B1922/77 or B1923/77 is not output.

      Tech Tips

      Codes other than DTCs B1920/77, B1921/77, B1922/77 and B1923/77 may be output at this time, but they are not related to this check.

    8. Turn the engine switch off.

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

    10. Disconnect SST from connector C.

      Result
      Proceed to
      OK
      NG

    OK

    REPLACE REAR SEAT 3 POINT TYPE OUTER BELT ASSEMBLY RH Click here

    NG

  3. CHECK FLOOR WIRE


    1. B002DYYC16
      *1 Rear Seat 3 Point Type Outer Belt Assembly RH
      *2 Airbag ECU Assembly
      *3 Floor Wire
      *a

      Front view of wire harness connector

      (to Rear Seat 3 Point Type Outer Belt Assembly RH)

      Disconnect the floor wire from the airbag ECU assembly.

    2. Check for a short to B+ in the circuit.


      1. Connect the cable to the negative (-) battery terminal.

      2. Turn the engine switch on (IG).

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

        Standard Voltage
        Tester Connection Switch Condition Specified Condition
        T23-1 (RR+) - Body ground Engine switch on (IG) Below 1 V
        T23-2 (RR-) - Body ground Engine switch on (IG) Below 1 V

      4. Turn the engine switch off.

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

    3. Check for an open in the circuit.


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

        Standard Resistance
        Tester Connection Condition Specified Condition
        T23-1 (RR+) - T23-2 (RR-) Always Below 1 Ω

    4. Check for a short to ground in the circuit.


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

        Standard Resistance
        Tester Connection Condition Specified Condition
        T23-1 (RR+) - Body ground Always 1 MΩ or higher
        T23-2 (RR-) - Body ground Always 1 MΩ or higher

    5. Check for a short in the circuit.


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

        Click here

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

        Standard Resistance
        Tester Connection Condition Specified Condition
        T23-1 (RR+) - T23-2 (RR-) Always 1 MΩ or higher

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

      Result
      Proceed to
      OK
      NG

    NG

    REPLACE FLOOR WIRE

    OK

  4. CHECK DTC


    1. B002EH2C23
      *1 Rear Seat 3 Point Type Outer Belt Assembly RH
      *2 Airbag ECU Assembly

      Connect the connectors to the rear seat 3 point type outer belt assembly RH and airbag ECU assembly.

    2. Connect the cable to the negative (-) battery terminal.

    3. Clear the DTCs stored in memory.

      Click here


      Body Electrical > SRS Airbag > Clear DTCs

    4. Turn the engine switch off.

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

    6. Check for DTCs.

      Click here


      Body Electrical > SRS Airbag > Trouble Codes
      OK
      DTC B1920/77, B1921/77, B1922/77 or B1923/77 is not output.

      Tech Tips

      Codes other than DTCs B1920/77, B1921/77, B1922/77 and B1923/77 may be output at this time, but they are not related to this check.

      Result
      Proceed to
      OK
      NG

    OK

    USE SIMULATION METHOD TO CHECK Click here

    NG

    REPLACE AIRBAG ECU ASSEMBLY Click here