2001 Twilight sentinel problem?

I have a 2001 SE that I think the twilight sentinel stopped working. When in the "on" position the headlights will not turn off. Anybody have any ideas on how to fix the problem. Is there a fuse that controls this feature or is it more complicated than that.

Thanks

I think I have to explain a little further about my problem. When I have the headlight switch in the auto position my headlights will not turn off. I can still operate the headlights manually but the timer that keeps them on for a minute or two does not seem to be working. any ideas.

Thanks