We recently bought a 97 Cad Deville, drove a few days and woke up to find the headlights stayed on all nite and ran down battery. My husband bought a repair manual and changed the headlight relay switch. Lights still stay on. I have heard from a car parts place it may be the twilight sentinal system. He’s a retired GM guy but this Caddy has everything on it and we’re used to Chevy’s. Any feedback will help!
Have you tried to operate the twilight sentinel or turn it off? Probably can’t be operated. If not that, the headlight delay?