brake lights on 2000 Mercedes-Benz ML320

why do my brake lights come on when I start my car
and stay on until I turn the car off

Asked by for the 2000 Mercedes-Benz ML320
Do you mean the brake lights at the rear of thee car are remaining on all the time, if so I would think the brake light switch has failed / shorted. If the brake light on the dash board is remaining illuminated I would check the brake fluid level in the fluid reservoir.
the 3 rear brake lights [ML320-2002] come on as long with the engine on, how to repair the switch ? please.
1 more answer
Looks like the brake light switch is bad,.if the cruse control won't work it is the switch.