I have a 2012 and am running nitto 295 70 17 trail grapplers, i aired down the tires to 30psi and set the procal to 24 but my tpms light is still on. what's going on, anybody have any experience.

 

If you aired the tires down first then reset the tpms setting, you've already thrown the tpms light on. That happened to me, and I ended up using the Procal feature to reset the codes, not the tpms setting, the codes thrown already. It's in their booklet how to do that.