I don't know about Utah's laws, but according to the League of American Bicyclists web site, if you wait for 3 minutes at a red light and it doesn't sense you, you can treat it like a stop sign (
reference here). I also had one bike instructor who said that if the sensor doesn't notice you, get off your bike and lay it down on the ground in the sensor area. It's a metal detector in the road that isn't picking you up, and supposedly doing that helps it recognize you better. I've never done that, though... I thought it might look a little weird, besides being pretty awkward.