RaceChrono Pro download link:RaceChrono Pro - Google Play 

Step1:
Open your phone's Bluetooth Settings, search for and tap "vLinker FD-Android".





Step2:
A request pairing prompt will be generated when pairing, enter the pairing code "1234" and click "OK".





Step3:
Successfully paired to the Bluetooth device "vLinker FD-Android".





Step4:
Open the app and click the Settings button in the upper right corner.





Step5:
Click on "Add OBD-II reader"





Step6:
Click on "Vgate vLinker/iCar BLE/BT4.0"





Step7:
Select OBD-II reader "vLinker FD-Android".





Step8:
Return to home page after selecting OBD II device.





Step9:
Click on "START"





Step10:
Connected successfully.