Abstract: An abnormality detecting device serves to detect abnormality of a low frequency oscillator. When a prescribed condition is satisfied, if the abnormality detecting device does not detect the abnormality of the low frequency oscillator, a switching device exchanges the clock pulse for operating a CPU from a first clock pulse to a second clock pulse so that the CPU is shifted to a low power consumed state. When a prescribed condition is satisfied, if the abnormality detecting device detects the abnormality of the low frequency oscillator, an exchange stopping device stops the exchange of the clock pulses by the exchange device. In this configuration, even when the abnormality occurs in the low frequency oscillator, disappearance of the information due to the resetting of the CPU can be prevented and the release of the low power consumed state in the other control units will not repeated.

Abstract: An abnormality detecting device 600 serves to detect abnormality of a low frequency oscillator. When a prescribed condition is satisfied, if the abnormality detecting device 600 does not detect the abnormality of the low frequency oscillator, a switching device 10a exchanges the clock pulse for operating a CPU 10 from a first clock pulse P1 to a second clock pulse P2 so that the CPU 10 is shifted to a low power consumed state. When a prescribed condition is satisfied, if the abnormality detecting device detects the abnormality of the low frequency oscillator, an exchange stopping device 10b stops the exchange of the clock pulse by the exchange device 10a. In this configuration, even when the abnormality occurs in the low frequency oscillator 42, disappearance of the information due to the resetting of the CPU 10 can be prevented and the release of the low power consumed state in the other control units will not repeated.