Abstract: A method is disclosed for controlling the brakes of a vehicle combination that includes a tractor vehicle and at least one trailer vehicle. A brake control valve in the tractor vehicle has magnetic switching valves that controlled by an electronic control unit, including an inlet valve and an outlet valve. To determine a current trailer status, it is determined whether the tractor vehicle is connected to a trailer vehicle and/or the line volume of the brake control line. A target pressure to be produced in the brake control line is specified and is produced by pulse-like opening of the inlet valve and/or the outlet valve. The brake control pressure in the brake control line is measured during the pressure build-up of pressure and a characteristic value for the trailer status and/or for the line volume of the brake control line is determined.