OCCUPANT CLASSIFICATION SYSTEM, Diagnostic DTC:B1798, B1799

DTC Code DTC Name
B1798 Yaw Rate Sensor Module Malfunction
B1799 Vehicle Stability Control ECU Malfunction

DESCRIPTION

The occupant detection ECU receives signals from the acceleration sensor (airbag sensor assembly) and skid control ECU via CAN communication.

DTC No. Detection Item DTC Detection Condition Trouble Area
B1798 Yaw Rate Sensor Module Malfunction Acceleration signals are abnormal

  • Acceleration sensor (Airbag sensor assembly)

  • CAN communication system
B1799 Vehicle Stability Control ECU Malfunction Vehicle speed signal from skid control ECU is abnormal

  • Skid control ECU (Brake booster with master cylinder assembly)

  • CAN communication system

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

Tech Tips


  • When DTC B1650/32 is stored as a result of troubleshooting for the airbag system, check the DTCs stored in the occupant detection ECU. When DTC B1798 or B1799 is output, perform troubleshooting for this DTC first.

  • If it is difficult to perform troubleshooting (wire harness inspection), remove the front passenger seat installation bolts to see under the seat cushion.

  • In the above case, lift and hold the seat so that it does not fall down. Hold the seat only as necessary because holding the seat for a long period of time may cause seat rail deformation.

PROCEDURE


  1. CHECK DTC (ELECTRONICALLY CONTROLLED BRAKE SYSTEM)


    1. Check for electronically controlled brake system DTCs.

      Click here

      OK
      DTCs are not output.
      Result
      Proceed to
      OK
      NG

    NG

    GO TO ELECTRONICALLY CONTROLLED BRAKE SYSTEM Click here

    OK

  2. CHECK CAN COMMUNICATION SYSTEM


    1. Using the GTS, check if the CAN communication system is functioning normally.

      OK
      CAN communication system is functioning normally.

      Tech Tips

      Refer to CAN Bus Check in CAN Communication System.

      Click here

      Result
      Proceed to
      OK
      NG

    NG

    GO TO CAN COMMUNICATION SYSTEM Click here

    OK

  3. CHECK DTC (HEALTH CHECK)


    1. Turn the power switch off.

    2. Connect the GTS to the DLC3.

    3. Turn the power switch on (IG) and turn the GTS on.

    4. Enter the following menus: System Select / Health Check.

      OK
      DTCs are not output.
      Result
      Proceed to
      OK
      NG

    OK

    USE SIMULATION METHOD TO CHECK Click here

    NG

    GO TO OTHER DIAGNOSTIC TROUBLE CODE CHART