1987 olds 98 backup lights on in drive and not in reverse

[elyk89]

as the title says i have an '87 98 and the reverse lights stay on in drive (regular drive, not overdrive) and no other gear including reverse. i looked through a book and it said something about a switch on the tranny that needs to be rotated/adjusted. not sure if that's what i need to do or not. need some help quick since i've got 7 more days to get it fixed or the ticket becomes really expensive.