A method is disclosed for detecting ground faults in a communications system. The method includes measuring a predetermined number of voltage points; determining if the measured voltage points represent recessive or dominant bits; identifying which of the predetermined number of voltage points represent inter-frame bits and which represent frame data bits based on whether the measured voltage points are recessive or dominant; calculating a maximum average voltage for the inter-frame bits; calculating an average frame voltage for all dominant bits within a frame; determining a high average dominant voltage count based on a number of frames for which the average frame voltage is greater than a high voltage threshold; and determining if a ground fault exists based on the average frame voltage and the high average dominant voltage count.