Abstract: A method of examining operation of an electronic control system for an internal combustion engine having a crankshaft, the control system having a mechanism for generating pulse signals indicative of angular position of the crankshaft and a processing circuit for evaluating the indicative pulse signals so as to output pulse signals for controlling an engine operation-related factor. The mechanism generates each indicative pulse signal at a time when the crankshaft is at one of predetermined angular positions. The processing circuit outputs each control pulse signal when the crankshaft is at a desired angular position. According to the method, the indicative pulse signals are continuously counted so as to generate a succession of counted numbers, each counted number representing the number of the indicative pulse signals generated during a time from an occurrence of one the control pulse signal to an occurrence of next the control pulse signal.

Abstract: A method of detecting the reference crank angle position in an internal combustion engine at the time of starting the engine, the engine having a crankshaft and a plurality of cylinders and associated with an ignition timing control device having a pulse signal generating mechanism including a rotor and a pair of first and second pulsers angularly spaced around the rotor for detecting passage of reactors disposed on the rotor. According to the method, the internal combustion engine is cranked, and the electric pulse signal generated by the first pulser is counted by a counter by referring to the content of a latch circuit. The counter is reset and enabled to count the electric pulse signal again when the reference crank angle position is not detected until the count of the counter reaches a predetermined count. The predetermined count being equal to a maximum number of electric pulses that can be generated by the first pulser while the rotor makes one revolution.