i had the same problem on my 92 f-150 auto hubs floor shift.
it would stay on for days or sometimes it would not come on at all.
you can tell if the hubs are locked when you turn the wheel so i never bothered with it. I checked the shaft to make sure it was free in 2wd and everytime i checked it was as it should be. just another idiot light.....lol
and wait till the window motors need replaced till you monkey with the locks....at ten years both motors went within 3 weeks of each other....go figure.