Why do my brake lights stay on while I am driving my Mercedes 2002 430s

Absolutely; Tried everything: even went to Mercedes yesterday. They scanned and could only guess the ESP. Exchanged new brake light switch with the one in wife's 430e. New one worked in hers; hers didn't work in my vehicle? Defiantly not switch. Don't know what to do next? Study the ESP module?

Brake light switch failure would be a prime suspect - switch always remains in the closed (ON) position.

Tried everything: even went to Mercedes yesterday. They scanned and could only guess the ESP. Exchanged new brake light switch with the one in wife's 430e. New one worked in hers; hers didn't work in my vehicle? Defiantly not switch.

Very unusual indeed. Well I’m out of ammo. Good luck with it!