Ignition Control Module: Description and Operation

Purpose

The Ignition Control Module (ICM) receives spark signals from the powertrain control module (PCM) and serves as an electric switch for the coil primary circuit.

Operation

Based on input signals, the powertrain control module will signal the ignition module to make corrections to the basic ignition timing. The computed ignition timing is determined by the engine speed, intake manifold vacuum (calculated by the intake air amount and engine speed) and EGR flow rate.