After refueling, turn the fuel tank cap until you hear a click. Once the cap is released, it will turn slightly in the opposite direction.

Caution
When replacing the fuel tank cap
Do not use anything but a genuine toyota fuel tank cap designed for your vehicle. Doing so may cause a fire or other incident which may result in death or serious injury.
Opening the fuel tank capRemoval
Disconnect cable from negative battery
terminal
Caution:
Wait at least 90 seconds after disconnecting the
cable from the negative (-) battery terminal to
prevent airbag and seat belt pretensioner activation.
Remove generator assembly
Remove the generator assembly from the vehicl ...
Components
...
Rear occupant classification sensor rh circuit malfunction
Description
The rear occupant classification sensor rh circuit consists of the occupant
classification ecu and the
rear occupant classification sensor rh.
Dtc b1783 is recorded when a malfunction is detected in the rear occupant
classification sensor rh
circuit.
Wiring diagram
...