When using the rear center seat belt, the buckle with the "CENTER" mark must be used.
Hyundai Elantra AD (2016-2020) Service Manual: Brake Booster Repair procedures
Brake Booster Operating Test
For simple checking of the brake booster operation, carry out the following tests.
1.
Run the engine for one or two minutes, and then stop it. If
the pedal depresses fully the first time but gradually becomes higher
when depressed succeeding times, the booster ...
Hyundai Elantra AD (2016-2020) Service Manual: Power Window Switch Components and Components Location
Components
[Driver Power Window Switch]
[Assist Power Window Switch]
[Rear Power Window Switch] ...