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

1. Turn the ignition switch to ON, and wait for at least 60 seconds.
2. Clear the DTCs stored in memory. Refer to DTC CHECK / CLEAR .

   HINT: 

   • First clear the DTCs stored in the occupant classification ECU, and then clear the DTCs stored in the center airbag sensor.
   • Use the Techstream to clear the DTCs of the occupant classification ECU, otherwise the DTCs cannot be cleared.
3. Turn the ignition switch off.
4. Turn the ignition switch to ON, and wait for at least 60 seconds.
5. Using the Techstream, check for DTCs of the occupant classification ECU. Refer to 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.

NG → See step   2 

OK → See step   13 

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

   OK

   Connectors are properly connected.

NG → CONNECT CONNECTOR 

OK: Go to next step 

1. Disconnect the connectors from the occupant classification ECU and 4 occupant classification sensors.
2. Check that the connectors (on the occupant classification ECU side and occupant classification sensor side) are not damaged. Refer to ELECTRONIC CIRCUIT INSPECTION PROCEDURE .

   OK

   Connectors 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, and wait for at least 2 seconds.
   Fig 1: Identifying Front Seat Wire RH

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   TEXT IN ILLUSTRATION
   
   

   *1	Front Seat Wire RH	*2	Occupant Classification Sensor
   *3	Occupant Classification ECU	*4	Connector B
   *5	Connector C	-	-
   *a	Front view of wire harness connector (to Occupant Classification ECU)	*b	Front view of wire harness connector (to Front Occupant Classification Sensor LH)
   *c	Front view of wire harness connector (to Front Occupant Classification Sensor RH)	*d	Front view of wire harness connector (to Rear Occupant Classification Sensor LH)
   *e	Front view of wire harness connector (to Rear Occupant Classification Sensor RH)	-	-

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

   Standard Voltage

   Tester Connection	Switch Condition	Specified Condition
   a10-11 (SVC1) - Body ground	Ignition switch ON	Below 1 V
   a10-12 (SVC2) - Body ground
   a10-5 (SVC3) - Body ground
   a10-6 (SVC4) - Body ground

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

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   a10-11 (SVC1) - a8-1 (SVC1)	Always	Below 1 Ω
   a10-12 (SVC2) - a6-1 (SVC2)
   a10-5 (SVC3) - a11-1 (SVC3)
   a10-6 (SVC4) - a5-1 (SVC4)
   a10-11 (SVC1) - a10-12 (SVC2)	Always	1 MΩ or higher
   a10-11 (SVC1) - a10-5 (SVC3)
   a10-11 (SVC1) - a10-6 (SVC4)
   a10-12 (SVC2) - a10-5 (SVC3)
   a10-12 (SVC2) - a10-6 (SVC4)
   a10-5 (SVC3) - a10-6 (SVC4)
   a10-11 (SVC1) - Body ground
   a10-12 (SVC2) - Body ground
   a10-5 (SVC3) - Body ground
   a10-6 (SVC4) - Body ground

NG → REPLACE FRONT SEAT WIRE RH 

OK: Go to next step 

1. Connect the connectors to occupant classification ECU and 4 occupant classification sensors.
2. Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.
3. Turn the ignition switch to ON, and wait for at least 60 seconds.
4. Clear the DTCs stored in memory. Refer to DTC CHECK / CLEAR .

   HINT: 

   • First clear the DTCs stored in the occupant classification ECU, and then clear the DTCs stored in the center airbag sensor.
   • Use the Techstream to clear the DTCs of the occupant classification ECU, otherwise the DTCs cannot be cleared.
5. Turn the ignition switch off.
6. Turn the ignition switch to ON, and wait for at least 60 seconds.
7. Using the Techstream, check for DTCs of the occupant classification ECU. Refer to 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.

NG → See step   6 

OK → See step   13 

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

   HINT: 

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

NEXT: Go to next step 

1. Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.
2. Turn the ignition switch to ON, and wait for at least 60 seconds.
3. Using the Techstream, perform the zero point calibration. Refer to INITIALIZATION .

   OK

   "Zero Point Calibration is complete." is displayed.

NG → See step   10 

OK: Go to next step 

1. Using the Techstream, perform the sensitivity check. Refer to INITIALIZATION .

   Standard range

   27 to 33 kg (59.5 to 72.8 lb)

NG → See step   10 

OK: Go to next step 

1. Clear the DTCs stored in memory. Refer to DTC CHECK / CLEAR .

   HINT: 

   • First clear the DTCs stored in the occupant classification ECU, and then clear the DTCs stored in the center airbag sensor.
   • Use the Techstream to clear the DTCs of the occupant classification ECU, otherwise the DTCs cannot be cleared.
2. Turn the ignition switch off.
3. Turn the ignition switch to ON, and wait for at least 60 seconds.
4. Using the Techstream, check for DTCs of the occupant classification ECU. Refer to 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.

NG → See step   10 

OK → END 

1. Turn the ignition switch off.
2. Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds.
3. for Manual Seat:
   1. Replace the separate type front seat cushion spring RH. Refer to DISASSEMBLY .
4. for Power Seat:
   1. Replace the separate type front seat cushion spring RH. Refer to DISASSEMBLY .

   HINT: 

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

NEXT: Go to next step 

1. Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.
2. Turn the ignition switch to ON, and wait for at least 60 seconds.
3. Using the Techstream, perform the zero point calibration. Refer to INITIALIZATION .

   OK

   "Zero Point Calibration is complete." is displayed.

NEXT: Go to next step 

1. Using the Techstream, perform the sensitivity check. Refer to INITIALIZATION .

   Standard range

   27 to 33 kg (59.5 to 72.8 lb)

NEXT → END