Patent ID: 7411514

Claim:
A failure detecting apparatus comprising: an input circuit for detecting resistance of a detecting resistor, the detecting resistor detecting a plurality of changes; a monitor circuit connected in parallel to the input circuit for monitoring a failure of the input circuit; and a control member which is supplied with the resistance of the detecting resistor detected by the input circuit and which detects a failure in the monitor circuit, upon the detection of which the control member switches from an inputting state, where the control member receives a signal from the monitor circuit, to an outputting state, where the control member sends a signal to the monitor circuit, wherein, in detecting the failure of the monitor circuit, the control member switches the monitor circuit from the inputting state to the outputting state and determines that the monitor circuit is out of order if a difference between an A/D converted value of the input circuit before the monitor circuit is switched from the inputting state to the outputting state and an A/D converted value of the input circuit after the monitor circuit has been switched from the inputting state to the outputting state is not within a predetermined range.