US Patent 7411514 Failure detecting apparatus

The failure detecting apparatus includes an input circuit 13 connected to a temperature sensor 53 to detect various changes, for detecting the resistance of the temperature sensor 53, a monitor circuit 14 connected in parallel to the input circuit 13 for monitoring the failure of the input circuit 13, and a CPU 1 which is supplied with the resistance of the temperature sensor 53 detected by the input circuit 13 and in detecting failure of the monitor circuit 14, switches its state between the inputting state receiving a signal from the monitor circuit 14 and the outputting state sending the signal to the monitor circuit 14.