To sense abnormality of a reverse rotation signal output system for a crank angle sensor with a reverse rotation detection sensing function for outputting a reverse rotation pulse signal at the time the engine rotation direction is reversed.
The crank angle sensor 34 commands output of an abnormality diagnosing pulse signal from a reverse rotation signal output system according to judgment by an abnormality diagnosing signal command circuit 46 in a predetermined period during cranking (such as a period until a forward rotation pulse signal is output for predetermined times) immediately after judgment that the power source of a crank angle sensor 34 is switched on (ignition switch is on) by a power source-on sensing circuit 45 as an abnormality diagnosing period so as to output a main pulse signal to a reverse rotation judging circuit 40. An ECU 36 judges whether or not the abnormality diagnosing pulse signal is output normally from the reverse rotation signal output system of the crank angle sensor 34 in the abnormality diagnosing period. In the case the abnormality diagnosing pulse signal is not output normally, it is judged that the reverse rotation signal output system of the crank angle sensor 34 suffers abnormality.
OBA NOBUKAZU
OKADA HIROSHI
KURUMADO NORIHIRO
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