Patent ID: 7520573

Claim:
A method for monitoring an active wheel speed sensor comprising the steps of: (a) providing an active wheel speed sensor that generates alternating high and low output signals; (b) sampling the high and low output signals of the wheel speed sensor within a sampling range that is dithered; (c) constructing high and low histograms corresponding to the high and low output signal samples obtained in step (b); (d) comparing the histogram values within each of the histograms to one another to determine whether a single histogram value for each of the histograms is dominate over the other values contained in that histogram; (e) comparing a voltage corresponding to the single dominant value of the high histogram to a threshold voltage value that is determined by the following formula: V TH =K*V L , where V TH is the voltage threshold, V L is the voltage value associated with the dominate value of the low histogram, and K is a constant associated with the wheel speed sensor; and (f) setting an error flag upon the voltage corresponding to the single dominant value of the high histogram being less than the threshold voltage value.