Press and hold one of the switches to open or close the car window. The circuit on left side is the driver side while the right side is one of the three passenger side (the other two are not shown). The window lock switch is near to the power supply.
When there is no button being pressed, the terminals of the motor is always connected to the positive. When any of the two buttons is pressed, one of terminals connects to the ground via relay, thus completing the circuit and turns the motor.
