Hi and welcome to NICO Club!
Sorry you're having issues with the Versa. Maybe take a look at the FSM for troubleshooting and diagnoses of your code. You'll be working with the EC chapter. Look at page EC-449. I know you got code P0715, but P1715 is like the factory code for the Nissan (at least this is my understanding). It looks like checking your wires is a starting point, before replacing the sensor. Look beyond the code as well. See if there's anything in there about the blinking cruise control light having a meaning. IMHO, if you fix the speed sensor, you should in turn fix the cruise control.
http://www.nicoclub.com/service-manual? ... 8_Versa/ec