According to the manual " 2131 Brake light switch". Possible cause connection wire between brake pedal switch for cruise control F47 and contact 4 of transmission control unit: open or short circuit. Repair Check function of brake light switch F, check connection between F and f47 to contact 4 of transmision control unit.
You can download electricl diagrams from audi V8Q Quattro Cobram hompages. It is for the North American market but should assist.
