A method for measuring a line resistance RL (7) and determining control line (16) faults in a hazard warning and control system. The control lines (16) connect a control device (20) to an actuator (10) using an actuation voltage UA in the case of an event and supplies the actuator (10) with a monitoring voltage UM in the case of a monitoring process using a monitoring module (21). Furthermore, the control device (20) has a constant current sink (6), which can be activated by a microcontroller (1), and a switchover device (5). In order to determine the line resistance RL (7), a constant voltage supply is provided in a measurement time interval ΔtM by an energy store (9) integrated into the monitoring module (21) and is fed back to the control device (20), and the switchover device (5) deactivates the monitoring voltage UM supply from the control device (20) to the actuator (10) during the entire measurement time interval ΔtM.