Dtc B1794 Open In Occupant Classification Ecu Battery Positive Line

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

DESCRIPTION

WIRING DIAGRAM

INSPECTION PROCEDURE

CHECK DTC

CHECK CONNECTION OF CONNECTORS

CHECK WIRE HARNESS (SOURCE VOLTAGE)

CHECK DTC

REPLACE OCCUPANT CLASSIFICATION ECU

PERFORM ZERO POINT CALIBRATION

PERFORM SENSITIVITY CHECK

DTC B1794 Open in Occupant Classification ECU Battery Positive Line


DESCRIPTION

DTC B1794 is set when a malfunction is detected in the occupant classification ECU battery positive line.

DTC No.
DTC Detecting Conditions
Trouble Areas
B1794
  1. Occupant classification ECU circuit malfunction
  2. Occupant classification ECU malfunction
  3. Occupant classification ECU detects short circuit to ground signal in passenger side buckle switch circuit for 2 seconds
  1. Wire harness
  2. Occupant classification ECU

WIRING DIAGRAM


Yaris. Ncp93, 131.Supplemental Restraint Systems.Airbag System (For Sedan). Dtc B1794 Open In Occupant Classification Ecu Battery Positive Line


INSPECTION PROCEDURE

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, and wait for at least 10 seconds.

  1. Turn the ignition switch to the on position.

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

    OK:
    DTC B1794 is not output.
    HINT:
    DTCs other than B1794 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.

    OK:
    The connectors are properly connected.


NG
CONNECT CONNECTORS
OK


3.CHECK WIRE HARNESS (SOURCE VOLTAGE)
Yaris. Ncp93, 131.Supplemental Restraint Systems.Airbag System (For Sedan). Dtc B1794 Open In Occupant Classification Ecu Battery Positive Line

  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. Disconnect the J24 connector from the occupant classification ECU.

  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
    J24-1 (+B) - Body ground
    		Ignition switch on
    		11 to 14 V
    J24-7 (IG) - Body ground
    		Ignition switch on
    		11 to 14 V

  1. Measure the resistance.

    Standard resistance:
    Tester Connection
    		Condition
    		Specified Condition
    J24-3 (GND) - Body ground
    		Always
    		Below 1 Ω


NG
REPAIR OR REPLACE HARNESS OR CONNECTOR (BATTERY - OCCUPANT CLASSIFICATION ECU)
OK


4.CHECK DTC

  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. Connect the connectors to the occupant classification ECU.

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

  1. Turn the ignition switch to the on position.

  1. Clear any 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, and wait for at least 10 seconds.

  1. Turn the ignition switch to the on position.

  1. Using the Techstream, check for DTCs of the occupant classification ECU (YARIS_NCP93 RM0000010VK06DX.html).

    OK:
    DTC B1794 is not output.
    HINT:
    DTCs other than B1794 may be output at this time, but they are not related to this check.


OK
USE SIMULATION METHOD TO CHECK
NG


5.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 when possible.

NEXT


6.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 on the tester.

NEXT


7.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

END