check for power at the switch.
check power after the switch is turned on
if theres power there, then check at the element... if theres power there then you have a bad element and you need a new one.
if there is no power after the switch they you have a bad switch.
if there is no power at the switch, get a schematic to find where the power comes from... check for power there... run a new wire if need be.
Best quesses in order..
fuse(theres going to be one somewhere... Im going to check my 98 tahoe for one tomorrow)