Brake pressure regulator and use of brake pressure regulator

The invention relates to a brake pressure regulator (110; 106) for a vehicle. The regulator comprises: a relay valve (202) to control the supply of pressurized air from a primary source (II) to at least one brake actuator (112a, 112b); a first valve subunit (204) configured to be electronically actuated wherein the first valve subunit (204) is configured to receive a primary control pressure from the primary source (II) intended to operate the relay valve (202), characterized by a second valve unit (206) configured to receive a secondary control pressure from the secondary source (II) intended to operate the relay valve (202). The second valve unit is configured to receive at least a secondary control pressure from a secondary source ("BST") and to receive at least a portion of the primary control pressure from the primary source (II), and to transmit either the primary control pressure or the secondary control pressure to the relay valve (202), and wherein the relay valve (202) is configured to receive the s