Last Modified: 04-05-2023 6.11:8.1.0 Doc ID: RM100000000VJS1
Model Year Start: 2016 Model: Sienna Prod Date Range: [12/2015 -           ]
Title: SUPPLEMENTAL RESTRAINT SYSTEMS: OCCUPANT CLASSIFICATION SYSTEM: B1793; Occupant Classification Sensor Power Supply Circuit Malfunction; 2016 - 2020 MY Sienna [12/2015 -        ]

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 stored when a malfunction is detected in the occupant classification sensor power supply circuit.

DTC Code

DTC Detection Condition

Trouble Area

B1793

One of following conditions is met:

  • Occupant classification ECU receives line short circuit signal, open circuit signal, short circuit to ground signal or short circuit to +B signal in occupant classification sensor power supply circuit for 2 seconds
  • Open circuit in occupant classification sensor wire harness
  • Occupant classification ECU malfunction
  • Front seat cushion spring assembly RH (Occupant classification sensors)
  • Front seat wire RH

HINT:

  • When DTC B1650/32 is detected as a result of troubleshooting the airbag system, perform troubleshooting for DTC B1793 of the occupant classification system.
  • Use the Techstream to check for DTCs of the occupant classification ECU, otherwise the DTCs cannot be read.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

HINT:

  • If troubleshooting (wire harness inspection) is difficult to perform, remove the front seat RH installation bolts to see the undersurface of the seat cushion.
  • In the above case, hold the seat so that it does not fall down. Holding the seat for a long period of time may cause problems, such as seat rail deformation. Hold the seat up only for as long as necessary.

PROCEDURE

1.

CHECK FOR DTC

(a) Turn the ignition switch to ON, and wait for at least 60 seconds.

(b) Clear any DTCs stored in the memory (See page 2016 - 2020 MY Sienna [12/2015 -        ]; SUPPLEMENTAL RESTRAINT SYSTEMS: OCCUPANT CLASSIFICATION SYSTEM: DTC CHECK / CLEAR ).

HINT:

  • First clear DTCs stored in the occupant classification ECU and then in the center airbag sensor assembly.
  • Use the Techstream to clear the DTCs of the occupant classification ECU, otherwise the DTCs cannot be cleared.

(c) Turn the ignition switch off.

(d) Turn the ignition switch to ON, and wait for at least 60 seconds.

(e) Using the Techstream, check for DTCs of the occupant classification ECU (See page 2016 - 2020 MY Sienna [12/2015 -        ]; SUPPLEMENTAL RESTRAINT SYSTEMS: OCCUPANT CLASSIFICATION SYSTEM: DTC CHECK / CLEAR ).

OK:

DTC B1793 is not output.

HINT:

DTCs other than DTC B1793 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 CONNECTOR

(a) Turn the ignition switch off.

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

(c) Check that the connectors are properly connected to the occupant classification ECU and the occupant classification sensors.

OK:

Connectors are properly connected.

NG

CONNECT CONNECTORS PROPERLY

OK

3.

CHECK CONNECTOR

(a) Check that the connectors (on the occupant classification ECU side and the occupant classification sensors side) are not damaged.

OK:

Connectors are not deformed or damaged.

NG

REPLACE FRONT SEAT WIRE RH

OK

4.

CHECK FRONT SEAT WIRE RH

(a) Disconnect the connectors from the occupant classification ECU and the 4 occupant classification sensors.

Text in Illustration

*1

Occupant Classification Sensor

*2

Occupant Classification ECU

*3

Front Seat Wire RH

*4

Front view of wire harness connector

(to Occupant Classification ECU)

*5

Front view of wire harness connector

(to Front Occupant Classification Sensor LH)

*6

Front view of wire harness connector

(to Front Occupant Classification Sensor RH)

*7

Front view of wire harness connector

(to Rear Occupant Classification Sensor LH)

*8

Front view of wire harness connector

(to Rear Occupant Classification Sensor RH)

*9

Connector B

*10

Connector C

(b) Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.

(c) Turn the ignition switch to ON, and wait for at least 60 seconds.

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

Standard Voltage:

Tester Connection

Switch Condition

Specified Condition

X7-11 (SVC1) - Body ground

Ignition switch ON

Below 1 V

X7-12 (SVC2) - Body ground

X7-5 (SVC3) - Body ground

X7-6 (SVC4) - Body ground

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

X7-11 (SVC1) - X5-1 (SVC1)

Always

Below 1 Ω

X7-12 (SVC2) - X3-1 (SVC2)

X7-5 (SVC3) - X8-1 (SVC3)

X7-6 (SVC4) - X1-1 (SVC4)

(f) Turn the ignition switch off.

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

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

X7-11 (SVC1) - Body ground

Always

1 MΩ or higher

X7-12 (SVC2) - Body ground

X7-5 (SVC3) - Body ground

X7-6 (SVC4) - Body ground

X7-11 (SVC1) - X7-12 (SVC2)

X7-12 (SVC2) - X7-5 (SVC3)

X7-12 (SVC2) - X7-6 (SVC4)

X7-11 (SVC1) - X7-5 (SVC3)

X7-11 (SVC1) - X7-6 (SVC4)

X7-5 (SVC3) - X7-6 (SVC4)

NG

REPLACE FRONT SEAT WIRE RH

OK

5.

CHECK FOR DTC

(a) Connect the connectors to the occupant classification ECU and the 4 occupant classification sensors.

(b) Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.

(c) Turn the ignition switch to ON, and wait for at least 60 seconds.

(d) Clear any DTCs stored in the memory (See page 2016 - 2020 MY Sienna [12/2015 -        ]; SUPPLEMENTAL RESTRAINT SYSTEMS: OCCUPANT CLASSIFICATION SYSTEM: DTC CHECK / CLEAR ).

HINT:

  • First clear DTCs stored in the occupant classification ECU and then in the center airbag sensor assembly.
  • Use the Techstream to clear the DTCs of the occupant classification ECU, otherwise the DTCs cannot be cleared.

(e) Turn the ignition switch off.

(f) Turn the ignition switch to ON, and wait for at least 60 seconds.

(g) Using the Techstream, check for DTCs of the occupant classification ECU (See page 2016 - 2020 MY Sienna [12/2015 -        ]; SUPPLEMENTAL RESTRAINT SYSTEMS: OCCUPANT CLASSIFICATION SYSTEM: DTC CHECK / CLEAR ).

OK:

DTC B1793 is not output.

HINT:

DTCs other than DTC B1793 may be output at this time, but they are not related to this check.

OK

USE SIMULATION METHOD TO CHECK

NG

6.

REPLACE FRONT SEAT CUSHION SPRING ASSEMBLY RH

(a) Turn the ignition switch off.

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

(c) Replace the front seat cushion spring assembly RH.

  • for Manual seat (See page 2016 - 2020 MY Sienna [12/2015 -        ]; SEAT: FRONT SEAT ASSEMBLY(for Manual Seat): REMOVAL ).
  • for Power seat (See page 2016 - 2020 MY Sienna [12/2015 -        ]; SEAT: FRONT SEAT ASSEMBLY(for Power Seat): REMOVAL ).

HINT:

Perform the inspection using parts from a normal vehicle when possible.

NEXT

7.

PERFORM ZERO POINT CALIBRATION

(a) Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.

(b) Connect the Techstream to the DLC3.

(c) Turn the ignition switch to ON, and wait for at least 60 seconds.

(d) Using the Techstream, perform the zero point calibration (See page 2016 - 2020 MY Sienna [12/2015 -        ]; SUPPLEMENTAL RESTRAINT SYSTEMS: OCCUPANT CLASSIFICATION SYSTEM: INITIALIZATION ).

NEXT

8.

PERFORM SENSITIVITY CHECK

(a) Using the Techstream, perform the sensitivity check (See page 2016 - 2020 MY Sienna [12/2015 -        ]; SUPPLEMENTAL RESTRAINT SYSTEMS: OCCUPANT CLASSIFICATION SYSTEM: INITIALIZATION ).

Standard range:

27 to 33 kg (59.5 to 72.8 lb)

NEXT

END