Ignition Control Module: Description and Operation
DescriptionThe ignition signal and ignition fail-safe signal provide crucial information in the control of the ignition system timing, injector timing, and fail-safe activation.
Operation
Based on an initial timing angle calculated from the crankshaft and the camshaft signals, the ECM/PCM outputs an ignition signal to the igniter as a reference point from which it determines ignition dwell period. A circuit within the Ignition Control Module (Igniter) controls the ignition dwell period by controlling the power transistor switch "ON." When the ECM/PCM determines the proper time to provide spark, it turns the ignition signal "OFF," which turns the Ignition Control Module (Igniter) power transistor "OFF," producing a spark. After the spark has occurred, the Ignition Control Module (Igniter) sends an ignition fail-safe signal back to the ECM/PCM, confirming that an ignition event has taken place. If the ignition fail-safe signal is not received by the ECM/PCM, a fail-safe mode is activated and injection operation is ceased, to protect the catalytic converter.