DTC B1793: Occupant Classification Sensor Power Supply Circuit Malfunction: Procedure

1. Turn the power switch off.
2. Disconnect the cable from the negative (-) battery terminal.
3. Check that the connectors are properly connected to the 4 occupant classification sensors and occupant classification ECU.

   OK

   The connectors are properly connected.

   HINT: 

   If the connectors are not connected securely, reconnect the connectors and proceed to the next inspection.

4. Disconnect the connectors from the 4 occupant classification sensors and occupant classification ECU.
5. Check that the terminals of connectors are not damaged.

   OK

   The terminals are not deformed or damaged.

NG → REPLACE FRONT SEAT WIRE RH 

OK: Go to next step 

1. Connect the cable to the negative (-) battery terminal.
   Fig 1: Identifying Front Seat Wire RH (Short To B+)

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Turn the power switch on (IG).
3. Measure the voltage according to the value(s) in the table below.

   Standard Voltage

   Tester Connection	Condition	Specified Condition
   W2-5 (SVC3) - Body ground	Power switch on (IG)	Below 1 V
   W2-6 (SVC4) - Body ground	Power switch on (IG)	Below 1 V
   W2-11 (SVC1) - Body ground	Power switch on (IG)	Below 1 V
   W2-12 (SVC2) - Body ground	Power switch on (IG)	Below 1 V

   TEXT IN ILLUSTRATION
   
   

   *1	Front view of wire harness connector (to Occupant Classification ECU)

NG → REPLACE FRONT SEAT WIRE RH 

OK: Go to next step 

1. Turn the power switch off.
   Fig 2: Identifying Front Seat Wire RH (Short To B+)

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Disconnect the cable from the negative (-) battery terminal.
3. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   W2-5 (SVC3) - Body ground	Always	1 MΩ or higher
   W2-6 (SVC4) - Body ground	Always	1 MΩ or higher
   W2-11 (SVC1) - Body ground	Always	1 MΩ or higher
   W2-12 (SVC2) - Body ground	Always	1 MΩ or higher

   TEXT IN ILLUSTRATION
   
   

   *1	Front view of wire harness connector (to Occupant Classification ECU)

NG → REPLACE FRONT SEAT WIRE RH 

OK: Go to next step 

1. Measure the resistance according to the value(s) in the table below.
   Fig 3: Identifying Front Seat Wire RH (Open)

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   W2-5 (SVC3) - W1-1 (SVC3)	Always	Below 1 Ω
   W2-6 (SVC4) - W7-1 (SVC4)	Always	Below 1 Ω
   W2-11 (SVC1) - W4-1 (SVC1)	Always	Below 1 Ω
   W2-12 (SVC2) - W6-1 (SVC2)	Always	Below 1 Ω

   TEXT IN ILLUSTRATION
   
   

   *1	Front view of wire harness connector (to Occupant Classification Sensor)
   *2	Front LH
   *3	Front RH
   *4	Rear LH
   *5	Rear RH
   *6	Front view of wire harness connector (to Occupant Classification ECU)

NG → REPLACE FRONT SEAT WIRE RH 

OK: Go to next step 

1. Measure the resistance according to the value(s) in the table below.
   Fig 4: Identifying Front Seat Wire RH (Short To B+)

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   W2-5 (SVC3) - W2-6 (SVC4)	Always	1 MΩ or higher
   W2-5 (SVC3) - W2-11 (SVC1)	Always	1 MΩ or higher
   W2-5 (SVC3) - W2-12 (SVC2)	Always	1 MΩ or higher
   W2-6 (SVC4) - W2-11 (SVC1)	Always	1 MΩ or higher
   W2-6 (SVC4) - W2-12 (SVC2)	Always	1 MΩ or higher
   W2-11 (SVC1) - W2-12 (SVC2)	Always	1 MΩ or higher

   TEXT IN ILLUSTRATION
   
   

   *1	Front view of wire harness connector (to Occupant Classification ECU)

NG → REPLACE FRONT SEAT WIRE RH 

OK: Go to next step 

1. Connect the connectors to the occupant classification ECU and 4 occupant classification sensors.
2. Connect the cable to the negative (-) battery terminal.
3. Turn the power switch on (IG).
4. Clear the DTCs stored in the occupant classification ECU. Refer to DTC CHECK / CLEAR .
5. Clear the DTCs stored in the center airbag sensor assembly. Refer to DTC CHECK / CLEAR .
6. Turn the power switch off.
7. Turn the power switch on (IG).
8. Check for DTCs. Refer to DTC CHECK / CLEAR .

   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.

NG → See step   7 

OK → See step   10 

1. Turn the power switch off.
2. Disconnect the cable from the negative (-) battery terminal.
3. Replace the front seat cushion spring assembly. Refer to DISASSEMBLY .

NEXT: Go to next step 

1. Connect the cable to the negative (-) battery terminal.
2. Connect the Techstream to the DLC3.
3. Turn the power switch on (IG).
4. Using the Techstream, perform Zero Point Calibration. Refer to INITIALIZATION .

   OK

   "Zero Point Calibration is complete." is displayed.

NEXT: Go to next step 

1. Using the Techstream, perform Sensitivity Check. Refer to INITIALIZATION .

   Standard

   27 to 33 kg (59.5 to 72.8 lb)

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