Service brake device of a vehicle, comprising a) at least one ABS pressure control valve which is controlled for slip-regulated braking by an electronic control unit, has at least one inlet valve and one outlet valve and is arranged upstream of a pressure medium actuated brake cylinder, b) a pressure medium line which supplies the ABS pressure control valve with pressure medium and into which a pressure controlled by a valve device arranged upstream of the ABS pressure control valve is feedable, c) at least one wheel rotational speed sensor and/or at least one acceleration sensor for measuring the longitudinal acceleration of the vehicle, wherein d) the valve device feeds a pressure derived from a reservoir pressure of a pressure medium reservoir into the pressure medium line as a function of an activation by the electronic control unit, wherein the electronic control unit is designed such that it e) directs the inlet valve and the outlet valve of the ABS pressure control valve into the blocking position, and then controls the valve device in order to feed the pressure derived from the pressure medium reservoir into the pressure medium line, within the course of a test run, and f) detects the value of the wheel slip which is then present by means of the wheel rotational speed sensor and/or the value of the vehicle acceleration or deceleration which is then present by means of the acceleration sensor and compares them with stored values, and g) generates an error signal in the event of a deviation, which is present in accordance with predetermined criteria, of the detected values from expected values, characterized in that h) the electronic control unit is furthermore designed such that, within the scope of controlling the valve device in order to feed the pressure derived from the pressure medium reservoir into the pressure medium line, it directs the inlet valve and the outlet valve of the ABS pressure control valve into the open position, and i) detects the value of the wheel slip which is then present by means of the wheel rotational speed sensor and/or the value of the vehicle acceleration or deceleration which is then present by means of the acceleration sensor and compares them with stored values, and j) generates an error signal in the event of a deviation, which is present in accordance with predetermined criteria, of the detected values from expected values. a) at least one ABS pressure control valve which is controlled for slip-regulated braking by an electronic control unit, has at least one inlet valve and one outlet valve and is arranged upstream of a pressure medium actuated brake cylinder, b) a pressure medium line which supplies the ABS pressure control valve with pressure medium and into which a pressure controlled by a valve device arranged upstream of the ABS pressure control valve is feedable, c) at least one wheel rotational speed sensor and/or at least one acceleration sensor for measuring the longitudinal acceleration of the vehicle, wherein d) the valve device feeds a pressure derived from a reservoir pressure of a pressure medium reservoir into the pressure medium line as a function of an activation by the electronic control unit, wherein the electronic control unit is designed such that it e) directs the inlet valve and the outlet valve of the ABS pressure control valve into the blocking position, and then controls the valve device in order to feed the pressure derived from the pressure medium reservoir into the pressure medium line, within the course of a test run, and f) detects the value of the wheel slip which is then present by means of the wheel rotational speed sensor and/or the value of the vehicle acceleration or deceleration which is then present by means of the acceleration sensor and compares them with stored values, and g) generates an error signal in the event of a deviation, which is present in accordance with predetermined criteria, of the detected values from expected values, characterized in that h) the electronic control unit is furthermore designed such that, within the scope of controlling the valve device in order to feed the pressure derived from the pressure medium reservoir into the pressure medium line, it directs the inlet valve and the outlet valve of the ABS pressure control valve into the open position, and i) detects the value of the wheel slip which is then present by means of the wheel rotational speed sensor and/or the value of the vehicle acceleration or deceleration which is then present by means of the acceleration sensor and compares them with stored values, and j) generates an error signal in the event of a deviation, which is present in accordance with predetermined criteria, of the detected values from expected values.