I just bought a 2007 DTS Performance and the brake lights stay on when the ignition is turned on. When I use the brakes they go off for about 2 seconds then come back on. They don't stay on when ignition is off. I changed the brake light switch. The master cylinder. Does anyone know what this issue could be?? I love the car and got a good price on it with only 84,000 miles and expect to have some bugs to work out but this braka light issue is something concerning.