| 摘要 |
PURPOSE:To detect the anomaly of each ignition coil by the simple constitution by installing an OR-circuit for taking in common each electric conduction signal for a plurality of ignition coils and detecting the anomaly of the ignition coil by judging the output level of the OR-circuit. CONSTITUTION:A CPU1 calculates igntion timing, electric conduction time, etc. according to each signal supplied from a sensor group 7. A frequency division circuit 2 distributes the ignition signals IGN calculated in the CPU1 to each cylinder. Transistors 3-6 drives the power transistor of each ignition coil. An indication circuit 8 displays the result of diagnosis. In the above- described constitution, diodes 9-12 which constitute an OR-circuit are arranged, and take out in common the signals IGN1-IGN4 for the ignition coils. Comparators 13-14 for detecting the breakage of wire and short-circuit of the primary coil of each ignition coil, having different voltage at the B and C points as standard voltage, are installed. Therefore, the taking-in of the signal for judging anomaly can be carried out through only one signal line from the A point.
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