Unwanted noise

[Dan_74]

The jb in my SL1 seems to be making a humming noise in the first position (selector switch) when I'm not playing but the volume is up.In the 2nd position it cuts the noise in half and positions 3-5 no noise at all.I thought it might just be because it's a humbucker,but I tried my WR1,Charvel 650xl and predator.I got no back noise from any of them.I even turned the amp volume way down and got the same thing. Anyone know what would cause this and maybe a way to fix?
Thanks!
Dan