There is a good chance that the switch has gone bad, mine did after only 4 months of use. The dealer who installed them put a volt meter on the switch and the power was getting to the switch but not passing over to the grips. The dealer ordered a new set and installed them for me free of charge. If the grips were installed by the dealer the warranty on the bike will cover the grips for the remainder of the bikes warranty.
Typically the grips only carry a 90 day warranty unless they are installed by the dealer, then they will have either the 90 days or the remainder of the bikes warranty which ever is greater.