I have noticed in my travels that any time an 07 and up Ram turns on it's signal light the corresponding headlight mysteriously turns of, be it a dsy light running light or a low beam.

WHY SO?

 

whoa, that sounds crazy..my truck doesnt do that...

 

Yah it does bert.. put on your e brake and put your truck in drive during the day with the headlights off.. put on your turn signal and get out and look.. your drls will turn off on the side that the turn signal is on whilethe signal flashes.. the only reason I can think for this is that its so you can see the turn signals better durring the day for oncoming cars.. both sides do it and if you are ever driving towards a ram on a gloomy day you will notice our drls are pretty damn bright..

 

I think DodgeThunder is correct.
However, i would need to look at a wiring schematic to further se all the details. if the DRL is ran off the same power supply as the directional(who knows with Chrysler??), that could be reason to cut power to one just to feed another. The standard parking like uses less wattage than a turn signal. This utilizes one power wire to feed diff lights.
Again, i don't know if that's the case or not, but i think DodgeThunder has the better theory of the two.

 

Whwe! I knew I wasn't crazy!

 

I think you will find that you have a Canadian truck. Here you are required to have your headlights on when the vehicle is in drive. To assist the on coming vehicles the corresponding headlight goes out. If you manually turn on your headlights this does not happen, the headlight stays on. This occurs on two of my vehicles.