Wheel speed sensor input circuit with sensor status detection employing a resistor biased compensator

A vehicle wheel speed detection circuit comprising:

• speed sensing means for generating an electrical speed signal indicative
• of a speed of rotation, said speed sensing means having a first
• output connector and a second output connector;
• comparator means having a first input electrically connected to said first output connector and a second input electrically connected to said second output connector for receiving said speed signal, said comparator means amplifying a difference between said signal first and second inputs and generating a comparator output signal on a comparator output line based thereon;
• a nonswitchable resistor electrically connected between said comparator output line and said first input where a resistance value of said resistor is substantially greater than a resistance value of said speed sensing means as measured between said first and second output connectors;
• and
• switching means for electrically connecting said second input to an electrical ground when in a test mode where said comparator means drives said comparator output signal to a high state when said speed sensing means is operational and said comparator means drives said comparator output signal to a low state when said speed sensing means is non-operational.