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

1. Turn the ignition switch to ON, and wait for at least 60 seconds.
2. Clear any DTCs stored in the memory. Refer to 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.
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 B1781 is not output.

   HINT: 

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

NG → See step   2 

OK → See step   9 

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 the front occupant classification sensor RH.

   OK

   Connectors are properly connected.

NG → CONNECT CONNECTORS PROPERLY 

OK: Go to next step 

1. Check that the connectors (on the occupant classification ECU side and front occupant classification sensor RH side) are not damaged.

   OK

   Connectors are not deformed or damaged.

NG → REPLACE FRONT SEAT WIRE RH 

OK: Go to next step 

Fig 1: Checking Front Seat Wire RH

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

1. Disconnect the connectors from the occupant classification ECU and the front occupant classification sensor RH.
2. Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.
3. Turn the ignition switch to ON.
4. Measure the voltage according to the value(s) in the table below.

   Standard Voltage

   Tester Connection	Switch Condition	Specified Condition
   M2-2 (SGD2) - Body ground	Ignition switch ON	Below 1 V
   M2-8 (SIG2) - Body ground
   M2-12 (SVC2) - Body ground

5. Turn the ignition switch off.
6. Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds.
7. Using service wires, connect terminals 1 (SVC2) and 3 (SGD2), and connect terminals 2 (SIG2) and 3 (SGD2) of connector C.
   NOTE:

   Do not forcibly insert the service wires into the terminals of the connector.

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

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   M2-8 (SIG2) - M2-2 (SGD2)	Always	Below 1 Ω
   M2-12 (SVC2) - M2-2 (SGD2)

9. Disconnect the service wires from connector C.
10. Measure the resistance according to the value(s) in the table below.

    Standard Resistance

    Tester Connection	Condition	Specified Condition
    M2-8 (SIG2) - M2-2 (SGD2)	Always	1 MΩ or higher
    M2-12 (SVC2) - M2-2 (SGD2)
    M2-8 (SIG2) - M2-12 (SVC2)
    M2-2 (SGD2) - Body ground
    M2-8 (SIG2) - Body ground
    M2-12 (SVC2) - Body ground

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 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 any DTCs stored in the memory. Refer to 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.
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 B1781 is not output.

   HINT: 

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

NG → See step   6 

OK → See step   9 

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 front seat with adjuster frame 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 (-) battery terminal, and wait for at least 2 seconds.
2. Connect the Techstream to the DLC3.
3. Turn the ignition switch to ON.
4. Using the Techstream, perform the zero point calibration. Refer to INITIALIZATION .

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