The invention relates to an arrangement and a method, the method comprising—uncoupling a mechanical coupler (M), —activating a first valve (2, 20) in response to the uncoupling of the mechanical coupler (M) by switching the first valve (2, 20) to a first state, —activating a valve unit (3, 30), —connecting an uncoupling control inlet (A) of the valve unit (3, 30) to a first valve unit outlet (34, 305) in response to the activation of the valve unit (3, 30), said uncoupling control inlet (A) being an inlet that is supplied by air from the MRP inlet (11), —deactivating an electrical coupler control device (6)—retracting the electrical coupler (E).