I am having the exact same problem, but, cannot seen to get an exact answer pinpointing the problem.
have replace resistor. twice
have replaced fuse, 2 times
and still it goes completely out,, it is not the switch, or it wouldn't work for a while and then quit, it is something else.
somebody said something about an "upgraded resistor" went to ford and the said they are all alike, really would like a good answer,, thanks again for the help