This is a repair to a common problem. The back light switch on the 03 tj is situated on the drivers side near the front of the tranny, right where the 4 wd mech is located. To replaced the switch. put the tranny in new trul so the the arm under neath is out of your way (block the wheels in both directions) unclip the switch plug, using a 22mm deep socket unscrew the switch from the tranny.A little oil may come out (a drop or two) put the new one in reconnect the wire and your done.
I called Cdn Tire and they quoted me $80. (I think the fellow made a mistake)
The Dealership price $32.
I paid under $20. at a local parts store near Montreal
So shop around for it