Dtc B1790 Center Airbag Sensor Assembly Communication Circuit Malfunction

Vehicle Interior. Yaris. Ncp93, 131
Supplemental Restraint Systems. Yaris. Ncp93, 131

DESCRIPTION

WIRING DIAGRAM

INSPECTION PROCEDURE

CHECK DTC

CHECK CONNECTION OF CONNECTORS

CHECK FLOOR WIRE (TO B+)

CHECK FLOOR WIRE (FOR OPEN)

CHECK FLOOR WIRE (FOR SHORT)

CHECK FLOOR WIRE (TO GROUND)

CHECK DTC

REPLACE OCCUPANT CLASSIFICATION ECU

PERFORM ZERO POINT CALIBRATION

PERFORM SENSITIVITY CHECK

CHECK DTC

DTC B1790 Center Airbag Sensor Assembly Communication Circuit Malfunction


DESCRIPTION

The center airbag sensor assembly communication circuit consists of the occupant classification ECU and the center airbag sensor assembly.
DTC B1790 is recorded when a malfunction is detected in the center airbag sensor assembly communication circuit.

DTC No.
DTC Detecting Condition
Trouble Area
B1790
  1. Occupant classification ECU detects line short circuit signal, open circuit signal, short circuit to ground signal or short circuit to B+ signal in center airbag sensor assembly communication circuit for 2 seconds
  2. Center airbag sensor assembly malfunction
  3. Occupant classification ECU malfunction
  1. Floor wire
  2. Occupant classification ECU
  3. Center airbag sensor assembly

WIRING DIAGRAM


Yaris. Ncp93, 131.Supplemental Restraint Systems.Airbag System (For Sedan). Dtc B1790 Center Airbag Sensor Assembly Communication Circuit Malfunction


INSPECTION PROCEDURE

HINT:
  1. If troubleshooting (wire harness inspection) is difficult to perform, remove the front passenger seat installation bolts to see the under surface of the seat cushion.
  2. In the above case, hold the seat so that it does not tip over. Holding the seat for a long period of time may cause a problem, such as seat rail deformation. Hold the seat up only for as long as necessary.
1.CHECK DTC

  1. Turn the ignition switch to the on position.

  1. Clear the DTCs stored in the memory (YARIS_NCP93 RM0000010VK06DX.html).

    HINT:
    First clear DTCs stored in the occupant classification ECU and then in the center airbag sensor assembly.

  1. Turn the ignition switch to the lock position.

  1. Turn the ignition switch to the on position.

  1. Check the DTCs (YARIS_NCP93 RM0000010VK06DX.html).

    OK:
    DTC B1790 is not output.
    HINT:
    Codes other than DTC B1790 may be output at this time, but they are not related to this check.


OK
USE SIMULATION METHOD TO CHECK
NG


2.CHECK CONNECTION OF CONNECTORS

  1. Turn the ignition switch to the lock position.

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

  1. Check that the connectors are properly connected to the occupant classification ECU and the center airbag sensor assembly.

    OK:
    The connectors are properly connected.


NG
CONNECT CONNECTORS
OK


3.CHECK FLOOR WIRE (TO B+)


    Yaris. Ncp93, 131.Supplemental Restraint Systems.Airbag System (For Sedan). Dtc B1790 Center Airbag Sensor Assembly Communication Circuit Malfunction

  1. Disconnect the connectors from the occupant classification ECU and the center airbag sensor assembly.

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

  1. Turn the ignition switch to the on position.

  1. Measure the voltage.

    Standard voltage:
    Tester connection
    		Condition
    		Specified condition
    J24-8 (FSR+) -
    Body ground
    		Ignition switch on
    		Below 1 V
    J24-4 (FSR-) -
    Body ground
    		Ignition switch on
    		Below 1 V


NG
REPAIR OR REPLACE FLOOR WIRE
OK


4.CHECK FLOOR WIRE (FOR OPEN)


    Yaris. Ncp93, 131.Supplemental Restraint Systems.Airbag System (For Sedan). Dtc B1790 Center Airbag Sensor Assembly Communication Circuit Malfunction

  1. Turn the ignition switch to the lock position.

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

  1. Using a service wire, connect J9-12 (FSP+) and J9-13 (FSP-) of connector B.

    NOTICE:
    Do not forcibly insert the service wire into the terminals of the connector when connecting.

  1. Measure the resistance.

    Standard resistance:
    Tester connection
    		Condition
    		Specified condition
    J24-8 (FSR+) -
    J24-4 (FSR-)
    		Always
    		Below 1 Ω


NG
REPAIR OR REPLACE FLOOR WIRE
OK


5.CHECK FLOOR WIRE (FOR SHORT)


    Yaris. Ncp93, 131.Supplemental Restraint Systems.Airbag System (For Sedan). Dtc B1790 Center Airbag Sensor Assembly Communication Circuit Malfunction

  1. Disconnect the service wire from connector B.

  1. Measure the resistance.

    Standard resistance:
    Tester connection
    		Condition
    		Specified condition
    J24-8 (FSR+) -
    J24-4 (FSR-)
    		Always
    		1 MΩ or higher


NG
REPAIR OR REPLACE FLOOR WIRE
OK


6.CHECK FLOOR WIRE (TO GROUND)


    Yaris. Ncp93, 131.Supplemental Restraint Systems.Airbag System (For Sedan). Dtc B1790 Center Airbag Sensor Assembly Communication Circuit Malfunction

  1. Measure the resistance.

    Standard resistance:
    Tester connection
    		Condition
    		Specified condition
    J24-8 (FSR+) -
    Body ground
    		Always
    		1 MΩ or higher
    J24-4 (FSR-) -
    Body ground
    		Always
    		1 MΩ or higher


NG
REPAIR OR REPLACE FLOOR WIRE
OK


7.CHECK DTC

  1. Connect the connectors to the occupant classification ECU and the center airbag sensor assembly.

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

  1. Turn the ignition switch to the on position.

  1. Clear the DTCs stored in the memory (YARIS_NCP93 RM0000010VK06DX.html).

    HINT:
    First clear DTCs stored in the occupant classification ECU and then in the center airbag sensor assembly.

  1. Turn the ignition switch to the lock position.

  1. Turn the ignition switch to the on position.

  1. Check the DTCs (YARIS_NCP93 RM0000010VK06DX.html).

    OK:
    DTC B1790 is not output.
    HINT:
    Codes other than DTC B1790 may be output at this time, but they are not related to this check.


OK
USE SIMULATION METHOD TO CHECK
NG


8.REPLACE OCCUPANT CLASSIFICATION ECU

  1. Turn the ignition switch to the lock position.

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

  1. Replace the occupant classification ECU (YARIS_NCP93 RM0000012DU00KX.html).

    HINT:
    Perform the inspection using parts from a normal vehicle if possible.

NEXT


9.PERFORM ZERO POINT CALIBRATION

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

  1. Connect the Techstream to the DLC3.

  1. Turn the ignition switch to the on position.

  1. Using the Techstream, perform the zero point calibration (YARIS_NCP93 RM0000010VN06EX.html).

    OK:
    COMPLETED is displayed.

NEXT


10.PERFORM SENSITIVITY CHECK

  1. Using the Techstream, perform the sensitivity check (YARIS_NCP93 RM0000010VN06EX.html).

    1. Confirm that nothing is placed on the passenger seat.

    2. Confirm that the beginning sensor reading is within the standard range.

      Standard range:
      -3.2 to 3.2 kg (-7 to 7 lb)

    3. Place a 30 kg (66.14 lb) weight (e.g. a lead mass) onto the front passenger seat.

    4. Confirm that the sensitivity is within the standard range.

      Standard range:
      27 to 33 kg (59.52 to 72.75 lb)
      HINT:
      When performing the sensitivity check, use a solid metal weight (the check result may not be accurate if a liquid weight is used).

NEXT


11.CHECK DTC

  1. Turn the ignition switch to the on position.

  1. Clear the DTCs stored in the memory (YARIS_NCP93 RM0000010VK06DX.html).

    HINT:
    First clear DTCs stored in the occupant classification ECU and then in the center airbag sensor assembly.

  1. Turn the ignition switch to the lock position.

  1. Turn the ignition switch to the on position.

  1. Check the DTCs (YARIS_NCP93 RM0000010VK06DX.html).

    OK:
    DTC B1790 is not output.
    HINT:
    Codes other than DTC B1790 may be output at this time, but they are not related to this check.


NG
REPLACE CENTER AIRBAG SENSOR ASSEMBLY
OK

END