tpms system keeps failing to calibrate my tire pressure light is on. any help?

There are a couple things you could check. One would be your relearn procedure which can be found in the owners manual. Two it could be a bad sensor. The tire sensors usually have a life of around 3-5 years. If a sensor needs to be replaced you can find them much cheaper online at http://www.titantpms.com/ rather than paying full retail at a dealership.