brake lights stay on when car is off?

Try adjusting the brake light switch, if not replace the turn signal flasher module here is the location. Check out the images (Below). Please let us know what happens.

this happened to me once, not in my Lesabre but another car, and the brake light switch, (the think your break pedal arm rests against when your foot is not on the break) was made of plastic and had actually broke. Shy of being virtually upside down this wasn't a difficult fix. Hope it's that simplistic for you. not some kind of more complex problem...