I have a speed sencer on right front wheel and my car doesn't have ABS what is this sencer used for?

Only the one sencer on front passenger side no other one's. If you unplug it no lights on dash come on.

Well, it must be for inputs to the transmission module or for speedometer reference maybe, I'm not familiar enough with the front hubs on the Rio to say for sure.. I've worked on quite a few of em but haven't had any reason yet to repair that particular part... I was just sure it had to have ABS but if it don't then it don't... Is there a problem or were you just courious?