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

1. Turn the power switch on (IG), and wait for at least 60 seconds.
2. Clear the DTCs. Refer to DTC CHECK / CLEAR .

   HINT: 

   • First clear the DTCs stored in the occupant detection ECU, and then clear the DTCs stored in the center airbag sensor assembly.
   • Use the Techstream to clear the DTCs of the occupant detection ECU, otherwise the DTCs cannot be cleared.
3. Turn the power switch off.
4. Turn the power switch on (IG), and wait for at least 60 seconds.
5. Check for DTCs. 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 power switch off.
2. Disconnect the cable from the negative (-) auxiliary battery terminal, and wait for at least 90 seconds.
3. Check that the connectors are properly connected to the occupant detection 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 detection ECU and 4 occupant classification sensors.
2. Check that the connectors (on the occupant detection ECU side and occupant classification sensor side) are not damaged. Refer to DIAGNOSIS SYSTEM .

   OK

   Connectors are not deformed or damaged.

NG → See step   14 

OK: Go to next step 

1. Connect the cable to the negative (-) auxiliary battery terminal, and wait for at least 2 seconds.
   Fig 1: Front Seat Wire Connector End View

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   TEXT IN ILLUSTRATION
   
   

   *1	Front Seat Wire RH	*2	Occupant Classification Sensor
   *3	Occupant Detection ECU	*4	Connector B
   *5	Connector C	-	-
   *a	Front view of wire harness connector (to Occupant Detection 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. Turn the power switch on (IG).
3. Measure the voltage according to the value(s) in the table below.

   Standard Voltage

   Tester Connection	Switch Condition	Specified Condition
   a1-11 (SVC1) - Body ground	Power switch on (IG)	Below 1 V
   a1-12 (SVC2) - Body ground
   a1-5 (SVC3) - Body ground
   a1-6 (SVC4) - Body ground

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

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   a1-11 (SVC1) - a2-1 (SVC1)	Always	Below 1 Ω
   a1-12 (SVC2) - a4-1 (SVC2)
   a1-5 (SVC3) - a3-1 (SVC3)
   a1-6 (SVC4) - a5-1 (SVC4)
   a1-11 (SVC1) - a1-12 (SVC2)	Always	1 MΩ or higher
   a1-11 (SVC1) - a1-5 (SVC3)
   a1-11 (SVC1) - a1-6 (SVC4)
   a1-12 (SVC2) - a1-5 (SVC3)
   a1-12 (SVC2) - a1-6 (SVC4)
   a1-5 (SVC3) - a1-6 (SVC4)
   a1-11 (SVC1) - Body ground
   a1-12 (SVC2) - Body ground
   a1-5 (SVC3) - Body ground
   a1-6 (SVC4) - Body ground

NG → See step   14 

OK: Go to next step 

1. Connect the connectors to occupant detection ECU and 4 occupant classification sensors.
2. Connect the cable to the negative (-) auxiliary battery terminal, and wait for at least 2 seconds.
3. Turn the power switch on (IG), and wait for at least 60 seconds.
4. Clear the DTCs. Refer to DTC CHECK / CLEAR .

   HINT: 

   • First clear the DTCs stored in the occupant detection ECU, and then clear the DTCs stored in the center airbag sensor assembly.
   • Use the Techstream to clear the DTCs of the occupant detection ECU, otherwise the DTCs cannot be cleared.
5. Turn the power switch off.
6. Turn the power switch on (IG), and wait for at least 60 seconds.
7. Check for DTCs. 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 power switch off.
2. Disconnect the cable from the negative (-) auxiliary battery terminal, and wait for at least 90 seconds.
3. Replace the occupant detection 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 (-) auxiliary battery terminal, and wait for at least 2 seconds.
2. Turn the power switch on (IG).
3. Perform the zero point calibration. Refer to INITIALIZATION .

NG → See step   10 

OK: Go to next step 

1. Perform the sensitivity check. Refer to INITIALIZATION .

NG → See step   10 

OK: Go to next step 

1. Clear the DTCs. Refer to DTC CHECK / CLEAR .

   HINT: 

   • First clear the DTCs stored in the occupant detection ECU, and then clear the DTCs stored in the center airbag sensor assembly.
   • Use the Techstream to clear the DTCs of the occupant detection ECU, otherwise the DTCs cannot be cleared.
2. Turn the power switch off.
3. Turn the power switch on (IG), and wait for at least 60 seconds.
4. Check for DTCs. 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 (OCCUPANT DETECTION ECU WAS DEFECTIVE) 

1. Turn the power switch off.
2. Disconnect the cable from the negative (-) auxiliary battery terminal, and wait for at least 90 seconds.
3. Replace the front seat assembly RH. 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 (-) auxiliary battery terminal, and wait for at least 2 seconds.
2. Turn the power switch on (IG).
3. Perform the zero point calibration. Refer to INITIALIZATION .

NEXT: Go to next step 

1. Perform the sensitivity check. Refer to INITIALIZATION .

NEXT → END (FRONT SEAT ASSEMBLY RH WAS DEFECTIVE)