You don't know HOW to manually tune to a radio station on your trucks radio? ANY RADIO can be manually tuned.
But if you are asking which radio stations in your area are not being used, click on the below website, type in your location, and they will list which radio staions/frequency's in your area are not being used:
What I am tring to say is it automatically tunes into a strong signal, how do you stop it in between there is no manual knob, there is only a seek and scan button, I have looked at all the menu optitons and cant find how to turn off aoto tune. Thanks