Digital TV:

Getting Digital TV reception can be hard as it depends on where your vehicle is in relation to broadcast towers, obstacles, broadcast power, topography, position of the vehicle, antenna placement etc.

As signals are now getting stronger your digital TV will pick up certain stations better than others, but it also depends on where you are in the country.  So basically there are a lot of variables

When adding the digital tuner you also need to tell the unit that you want to use the digital tuner.  This is quite simply done by going to:

and scroll down till you see Factory Settings
enter 1234
and select the Digital TV option there..