Also verify your brake light switch, connector C104 under the dash (that feeds the whole rear of the car) and the brake bulbs themselves.

All cars have a brake switch, M/T has a clutch switch too. If either switch is on the hairy edge it might bounce the contacts going over bumps and dump the cruise.

Remember that the cc passes current through the brake bulbs to ground to permit engagement. If the ground path fails the cruise will drop out.

Hitting a bump screams loose connection or miss adjusted switch to me.

__________________
The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech