The dash lights on my 2000 Buick Century are not working. No dash lights including light indicating which gear is selected. Also gas gauge does not work.
Sounds like the ground wire for the instrument cluster needs to be re-attached. It also could be an instrument voltage regulator, but I don’t think they are used for the dash lights.
Have You Checked All Fuses And Have you Checked To Make Sure You Have Not Just Brake Lights, But Tail Lights, As Well ?
CSA