9900 cab lights

[the missing link]

So I have a 9900 2007-8 depending on which way you go .
The cab light ( 3 way switch ) will start acting up every once and a while , the lights will start coming on and off by them self . Really sucks at night . So I did what every decent redneck would do I pulled the fuse and forgot about it for awhile but winter coming and I would like to fix them , just don't know where to start. Even if the switch is on / off / door they still do it .
Is it a bad ground or door switch , wiring , ect .if any body has run in to this, help a brother out please .

Thank- you