Basic Principles

No.5 pin of ECU controls the closing of main relay coil,and then primary winding+B of ignition coil is charged.When No.99 and 100 pin of ECU controls the primary winding of ignition coil 2 and 1 to be grounded respectively,the primary winding of two ignition coils are magnetized respectively.And when No.99 and 100 pin of ECU controls the primary circuit of ignition coil 2 and 1 to be broken respectively,the two secondary winding will separately sense the high voltage and each spark plug will discharge and ignite.The principle of electric circuit is shown in Fig.4.22.

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Fig.4.22 Electric Circuit Diagram of CX70 Ignition System