| 摘要 |
PURPOSE:To detect malfunction of an oscillator of an ignition control device with ease and prevent an engine from being interrupted, by determining that the oscillator is in malfunction when it does not output a clock signal and making ignition based on an ignition timing signal which is in synchronism with the rotation of the engine. CONSTITUTION:A ignition device 7 is supplied with an output signal from a control circuit 4 for energizing an ignition coil intermittently. ON the other hand, when a clock pulse is not output, the control circuit 4 interrupts to calculate an energizing timing and does not output an energizing timing signal. However, since a malfunction detection circuit 5 detects that the energizing timing signal is not output and a switching circuit 6 switches an output signal from the control circuit 4 to a waveform shaping circuit 2, the ignition device 7 continues to energize the ignition coil without interruption for thereby not interrupting an engine. In addition, the malfunction detection circuit 5 also outputs a signal to a display circuit 8 so that a drive is notified of the malfunction. Therefore, malfunction of an oscillator 3 can be detected with ease and the engine is prevented from being interrupted.
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