US Patent 7136780 Abnormality diagnosis apparatus for automatic activation timer circuit

An abnormality diagnosis apparatus for determining whether abnormality relating to execution of automatic activation has occurred in a timer circuit. An electronic control unit includes a microcomputer for storing a history of execution of automatic activation of a device by a soak timer circuit. The microcomputer determines that an abnormality relating to execution of automatic activation has occurred in the soak timer circuit if an elapsed time measurement and the history stored by the microcomputer do not correspond with each other when a switch is operated to activate the device.