Toyota RAV4 manuals

Toyota Sienna Service Manual: Occupant Classification Sensor Power Supply Circuit Malfunction

DTC B1793 Occupant Classification Sensor Power Supply Circuit Malfunction

DESCRIPTION

The occupant classification sensor power supply circuit consists of the occupant classification ECU and the occupant classification sensors.

DTC B1793 is recorded when a malfunction is detected in the occupant classification sensor power supply circuit.

DTC No.

DTC Detecting Condition

Trouble Area

B1793

  • The occupant classification ECU receives a line short circuit signal, an open circuit signal, a short circuit to ground signal or a short circuit to B+ signal in the occupant classification sensor power supply circuit for 2 seconds.
  •  Occupant classification ECU malfunction
  • Front seat assembly RH (Occupant classification sensors)
  •  Occupant classification ECU
  •  Front seat wire RH

WIRING DIAGRAM

WIRING DIAGRAM

INSPECTION PROCEDURE

HINT:

1 CHECK DTC

  1. Turn the ignition switch to the ON position.
  2.  Clear the DTCs stored in the memory.

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

  3.  Turn the ignition switch to the LOCK position.
  4.  Turn the ignition switch to the ON position.
  5.  Check the DTCs (35).

OK: DTC B1793 is not output. HINT: Codes other than DTC B1793 may be output at this time, but they are not related to this check.

2 CHECK CONNECTION OF CONNECTORS

  1. Turn the ignition switch to the LOCK position.
  2.  Disconnect the negative (-) terminal cable from the battery, and wait for at least 90 seconds.
  3.  Check that the connectors are properly connected to the occupant classification ECU and the occupant classification sensors.

OK: The connectors are properly connected

3 CHECK FRONT SEAT WIRE RH (SHORT TO B+)

CHECK FRONT SEAT WIRE RH (SHORT TO B+)

  1. Disconnect the connectors from the occupant classification ECU and the 4 occupant classification sensors.
  2.  Connect the negative (-) terminal cable to the battery.
  3.  Turn the ignition switch to the ON position.
  4.  Measure the voltage according to the value(s) in the table below.

Standard voltage

Standard voltage

4 CHECK FRONT SEAT WIRE RH (SHORT TO GROUND)

CHECK FRONT SEAT WIRE RH (SHORT TO GROUND)

  1. Turn the ignition switch to the LOCK position.
  2.  Disconnect the negative (-) terminal cable from the battery, and wait for at least 90 seconds.
  3.  Measure the resistance according to the value(s) in the table below.

Standard resistance

Standard resistance

5 CHECK FRONT SEAT WIRE RH (OPEN)

CHECK FRONT SEAT WIRE RH (OPEN)

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

Standard resistance

Standard resistance

6 CHECK FRONT SEAT WIRE RH (SHORT)

CHECK FRONT SEAT WIRE RH (SHORT)

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

Standard resistance

Standard resistance

7 CHECK DTC

  1. Connect the connectors to the occupant classification ECU and the 4 occupant classification sensors.
  2.  Connect the negative (-) terminal cable to the battery.
  3.  Turn the ignition switch to the ON position.
  4.  Clear the DTCs stored in the memory.

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

  5.  Turn the ignition switch to the LOCK position.
  6.  Turn the ignition switch to the ON position.
  7.  Check the DTCs (35).

OK: DTC B1793 is not output. HINT: Codes other than DTC B1793 may be output at this time, but they are not related to this check.

8 REPLACE OCCUPANT CLASSIFICATION ECU

  1. Turn the ignition switch to the LOCK position.
  2.  Disconnect the negative (-) terminal cable from the battery, and wait for at least 90 seconds.
  3.  Replace the occupant classification ECU.

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

9 PERFORM ZERO POINT CALIBRATION

  1. Connect the negative (-) terminal cable to the battery.
  2.  Connect the intelligent tester to the DLC3.
  3.  Turn the ignition switch to the ON position.
  4.  Using the intelligent tester, perform "Zero point calibration" (28).

    OK: "COMPLETED" is displayed

10 PERFORM SENSITIVITY CHECK

  1. Using the intelligent tester, perform "Sensitivity check" (28).

    Standard value: 27 to 33 kg (59.52 to 72.75 lb)

11 CHECK DTC

  1.  Turn the ignition switch to the ON position.
  2.  Clear the DTCs stored in the memory.

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

  3.  Turn the ignition switch to the LOCK position.
  4.  Turn the ignition switch to the ON position.
  5.  Check the DTCs (35).

OK: DTC B1793 is not output. HINT: Codes other than DTC B1793 may be output at this time, but they are related to this check

12 REPLACE FRONT SEAT ASSEMBLY RH

  1. Turn the ignition switch to the LOCK position.
  2.  Disconnect the negative (-) terminal cable from the battery, and wait for at least 90 seconds.
  3.  Replace the front seat assembly RH ( for flat type, SE-48 for manual seat, SE-58 for power seat).

13 PERFORM ZERO POINT CALIBRATION

  1. Connect the negative (-) terminal cable to the battery.
  2. Connect the intelligent tester to the DLC3.
  3.  Turn the ignition switch to the ON position.
  4. Using the intelligent tester, perform "Zero point calibration" (28).

    OK: "COMPLETED" is displayed.

14 PERFORM SENSITIVITY CHECK

  1. Using the intelligent tester, perform "Sensitivity check" (28).

    Standard value: 27 to 33 kg (59.52 to 72.75 lb)

END

Center Airbag Sensor Assembly Communication Circuit Malfunction
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 ...

Open in Occupant Classification ECU Battery Positive Line
DTC B1794 Open in Occupant Classification ECU Battery Positive Line DESCRIPTION This circuit consists of the occupant classification ECU and the power source circuit (battery, fuse, wire harness ...

Other materials:

Fail-safe chart
1. AUTO CANCEL FUNCTION (FAIL-SAFE FUNCTION): HINT: If a system malfunction occurs, the applicable DTCs will appear on the multi-information display. In some cases, a DTC will be set due to weather or vehicle operating conditions, this does not indicate a system malfunction.  E3 (i ...

Location of the spare tire, jack and tools
Spare tire Jack handle Tire bag Jack Wheel nut wrench Adapter socket Tire strap WARNINGUsing the tire jack Observe the following precautions. Improper use of the tire jack may cause the vehicle to suddenly fall off the jack, leading to death or serious injury. ...

Removal
1. DISCONNECT CABLE FROM NEGATIVE BATTERY TERMINAL 2. REMOVE ROOF HEADLINING ASSEMBLY HINT: Refer to the instructions for REMOVAL of the ROOF HEADLINING (See page IR-6). 3. REMOVE TIRE PRESSURE WARNING RECEIVER ASSEMBLY (a) Remove the bolt. (b) Disconnect the connector and remove the ...

В© 2011-2021 Copyright www.tsienna.net