Method for controlling an electropneumatic ABS brake system in a towing vehicle, function control device and towing vehicle

A method is for controlling an ABS brake system. A trailer control pressure is transmittable via a trailer control valve to a trailer to trigger trailer wheel brakes as a function of the trailer control pressure. The trailer control pressure for implementing an emergency brake function or an auxiliary brake function is delivered as a function of a position of an operating element. The method includes: determining a position of the operating element; determining a trailer target pressure as a function of the position; generating and delivering a trailer control pressure corresponding to the trailer target pressure to the control valve; determining an actual towing vehicle deceleration; reading a minimum deceleration associated with the determined position; and triggering brakes of the towing vehicle when the actual deceleration falls below the minimum deceleration read, such that the trailer control pressure does not change and the actual towing vehicle deceleration increases.