Control apparatus for internal combustion engine

A control apparatus for controlling operation of an internal combustion engine, comprising:

• reference position signal generating means for generating a reference position signal indicating reference positions of individual cylinders of said engine in synchronism with rotation of said engine;
• a plurality of cylinder identification signal generating means for generating a plurality of cylinder identification signals each different from the other in synchronism with rotation of said engine;
• and
• control means for controlling said engine on the basis of said reference position signal and said cylinder identification signals;
• wherein each of said cylinder identification signals includes a plurality of mutually complementary pulses corresponding to said individual cylinders, respectively;
• said plurality of pulses comprising pulses having different pulse widths corresponding to said reference positions;
• and
• wherein said control means includes:
• first determining means for determining whether each of said cylinder identification signals is within normal expected criteria;
• first back-up means responsive to an output of said first determining means indicating that one of said cylinder identification signals is abnormal, to thereby control operation of said engine on the basis of the other cylinder identification signal and said reference position signal;
• second determining means for determining whether said reference signal is normal;
• and
• second back-up means responsive to an output of said second determining means indicating that said reference position signal is abnormal, to thereby control operation of said engine on the basis of said cylinder identification signals.