When I press my break pedal my rear brake lights and third will not work. on 2003 Cadillac Escalade

I didn't have this problem before. All at once they stopped working

Asked by for the 2003 Cadillac Escalade
Any problem shifting transmission out of park???? ... IF no.... Possible multifunction (signal light) switch!!!!
2 answers
Check brake fuse, and/or brake light switch.