The brake light switch can fail allowing the switch to remain in the "brake lights off" position or in the "brake lights on" position.
Lights
BMW 735I Lighting problems by year
2 complaints filed with NHTSA about the BMW 735I's lights. Headlights, tail lights, brake lights, turn signals and interior lighting failures.
Lighting complaints by model year
Lighting recalls
Latest 735I lighting complaints
Mustard colored relay (tail light assembly) 61 31 1 378 052 solder points failed (same as previously reported lkm mosule)
TAIL LIGHT FAILURE.
Source: U.S. National Highway Traffic Safety Administration (NHTSA) complaints and recalls, checked daily. Complaints are owners' own reports and are not verified. How we use the data