When I had a 2008 Bighorn I converted the thermostat to a Hunter digital. About $20 at WalMart.
I am surprised that you have only two wires going to your thermostat. That doesnt make sense.
If you look in the WIKI, found at the top of the page, under Index of How-To's, look for Thermostat and you will find wiring diagrams for the conversion.
Hope this is of some help.
Peace
Dave