The brake light switch has failed
If the brake lights stay on that probably means the switch on the brake pedal that activates them is defective.
faulty brake switch
The most common cause for brake lights to be out on a 2001 Mustang GT is a blown bulb. There are some instances where there is faulty wiring.
check fuses, check brake light switch behind brake pedal.
It is not necessarily the fuse. It could be the switch on the brake that is not closing the circuit.
They are burned out.
dodge 2001 Dakota brake lights won't burn Check the fuses. If the fuses are okay check the brake light switch.
Check the brake light switch. This can cause the brake lights to go out. There have been a couple of recalls on the 2001 for this exact problem. Contact your local VW dealer and have the switch replaced.
it maybe the brake switch
check your fuses
This is usually cause by a stuck brake light switch on the brake pedal. Replace it.
Look behind a panel in the trunk