Mine would do the same thing. Somtimes when I would start my car light would come on in the dash, and I would know that it was working. I could use the switch and everything, but when it didn't the switch would not work.
I don't know what the problem was because I finally just pulled the fuse anyway. Now it's like a brand new car. I can finally use 1st and 2nd gear without the F'ing TRAC slowing me down.