After you plug the vModem and open the ReadCar, your phone will connect the vModem in 10 seconds automatically, then the icon () will light, as it shows in Picture 1.

If your adapter is not the vModem, you should press the icon (settings -> Bluetooth -> select vModem), then select a proper adapter, as it shows in Picture 2.

Tips: please use the soft in the car, as a result of the connection distance of Bluetooth is only 5 meters.