It sounds simular to my wife's old 1990 Toyota corolla. I replaced the cracked plastic peice that tells you what gear your in and put in a new bulb . What I did not do right is disconnect the netive battery terminal before disassembling and re assembling . I found out that a fush controls an arm the locks the transmission for safety reasons , The mechcanic down the street new what I had done and after reinstalling a new fuse it was brand new again.
Do your research and ask questions it is bound to keep you out of trouble.
Bob Geco
Not a mechanic but like to work on my cars.