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 capIllumination circuit
Description
The main body ecu receives information regarding the door courtesy switch and
door lock position
switch, and turns on the room light.
Wiring diagram
Inspection procedure
Perform active test by intelligent tester (main body ecu)
Connect the intelligent tester (with can ...
Data list / active test
Active test
Hint:
Performing the intelligent tester active test allows
relay, vsv, actuator and other items to be operated
without removing any parts. Performing the active
test early in troubleshooting is one way to save time.
The data list can be displayed during the active
test.
...
System description
Key reminder warning system description
When the driver side door is opened with the key in
the ignition key cylinder and ignition switch in the
acc or off position, this system causes the key
reminder warning buzzer to sound in order to warn
the driver that the ignition key has not ...