DTC B1781: Front Occupant Classification Sensor RH Circuit Malfunction: Procedure

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

   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 occupant classification ECU and the front occupant classification sensor RH.
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 negative (-) terminal cable to the battery.
   Fig 1: Checking Front Seat Wire RH (Short To B+)

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

   Standard voltage

   Tester Connection	Switch Condition	Specified Condition
   a1-2 (SGD2) - Body ground	Ignition switch on (IG)	Below 1 V
   a1-8 (SIG2) - Body ground	Ignition switch on (IG)	Below 1 V
   a1-12 (SVC2) - Body ground	Ignition switch on (IG)	Below 1 V

NG → REPLACE FRONT SEAT WIRE RH 

OK: Go to next step 

1. Turn the ignition switch off.
   Fig 2: Checking Front Seat Wire RH (Open)

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Disconnect the negative (-) terminal cable from the battery.
3. Using SST, connect terminals 1 (SVC2) and 3 (SGD2), and connect terminals 2 (SIG2) and 3 (SGD2) of connector C.
   NOTE:

   Do not forcibly insert SST into the terminals of the connector when connecting.

   • SST: 09843-18040 
4. Measure the resistance according to the value(s) in the table below.

   Standard resistance

   Tester Connection	Switch Condition	Specified Condition
   a1-8 (SIG2) - a1-2 (SGD2)	Always	Below 1 Ω
   a1-12 (SVC2) - a1-2 (SGD2)	Always	Below 1 Ω

NG → REPLACE FRONT SEAT WIRE RH 

OK: Go to next step 

1. Disconnect SST from connector C.
   Fig 3: Checking Front Seat Wire RH (Short To B+)

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Measure the resistance according to the value(s) in the table below.

   Standard resistance

   Tester Connection	Switch Condition	Specified Condition
   a1-8 (SIG2) - a1-2 (SGD2)	Always	1 MΩ or higher
   a1-12 (SVC2) - a1-2 (SGD2)	Always	1 MΩ or higher
   a1-8 (SIG2) - a1-12 (SVC2)	Always	1 MΩ or higher

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: Checking Front Seat Wire RH (Short To B+)

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   Standard resistance

   Tester Connection	Switch Condition	Specified Condition
   a1-2 (SGD2) - Body ground	Always	1 MΩ or higher
   a1-8 (SIG2) - Body ground	Always	1 MΩ or higher
   a1-12 (SVC2) - Body ground	Always	1 MΩ or higher

NG → REPLACE FRONT SEAT WIRE RH 

OK: Go to next step 

1. Connect the connectors to the occupant classification ECU and the front occupant classification sensor RH.
2. Connect the negative (-) terminal cable to the battery.
3. Turn the ignition 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 ignition switch off.
7. Turn the ignition switch on (IG).
8. Check for DTCs. Refer to DTC CHECK / CLEAR .

   OK

   DTC B1781 is not output.

   HINT: 

   Codes other than DTC B1781 may be output at this time, but they are not related to this check.

NG → See step   7 

OK → See step   14 

1. Turn the ignition switch off.
2. Disconnect the negative (-) terminal cable from the battery.
3. Replace the occupant classification ECU. Refer to REMOVAL .

   HINT: 

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

NEXT: Go to next step 

1. Connect the negative (-) terminal cable to the battery.
2. Connect Techstream to the DLC3.
3. Turn the ignition switch on (IG).
4. Using Techstream, perform "zero point calibration". Refer to INITIALIZATION .

   OK

   "Zero Point Calibration is complete." is displayed.

NG → See step   11 

OK: Go to next step 

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

   Standard

   27 to 33 kg (59.52 to 72.75 lb)

NG → See step   11 

OK: Go to next step 

1. Turn the ignition switch on (IG).
2. Clear the DTCs stored in the occupant classification ECU. Refer to DTC CHECK / CLEAR .
3. Clear the DTCs stored in the center airbag sensor assembly. Refer to DTC CHECK / CLEAR .
4. Turn the ignition switch off.
5. Turn the ignition switch on (IG).
6. Check for DTCs. Refer to DTC CHECK / CLEAR .

   OK

   DTC B1781 is not output.

   HINT: 

   Codes other than DTC B1781 may be output at this time, but they are not related to this check.

NG → See step   11 

OK → END 

1. Turn the ignition switch off.
2. Disconnect the negative (-) terminal cable from the battery.
3. Replace the front seat frame with adjuster assembly RH. Refer to REMOVAL for power seat or, refer to REMOVAL for manual seat.

NEXT: Go to next step 

1. Connect the negative (-) terminal cable to the battery.
2. Connect Techstream to the DLC3.
3. Turn the ignition switch on (IG).
4. Using Techstream, perform "zero point calibration". Refer to INITIALIZATION .

   OK

   "Zero Point Calibration is complete." is displayed.

NEXT: Go to next step 

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

   Standard

   27 to 33 kg (59.52 to 72.75 lb)

NEXT → END