I am not the best with wranglers, especially TJ,s I really know nothing about them, I know the cj models. Know one has answered you post yet, so I will try to give you a place to start. It sounds like the wires to the 4wd light are on backwards, 2wd activates it and 4wd turns it off. It is just a light, and the position of the shifter dictates 4wd or not, so you are not driving around in 4wd with the shifter in 2wd when the light is on. Just in case you were worried about that. I am just guessing with the crossed wires, so listen to the others if they post a answer.