Ignition Power Stage: Description and Operation

Fig. 2 Ignition Amplifier:

The ignition amplifiers receive ignition signals from the ECM and controls the primary current of the ignition coils. The switching of the current generates a high voltage at the secondary windings of the ignition coils.

The ignition monitoring circuit senses the primary current of the ignition coils and informs the ECM that correct ignition has occurred. If the information indicates incorrect ignition, the ECM stops fuel injection to the relevant bank and provides "limp home" mode for the other bank.