F 350 4WD Pickup V8-351 5.8L VIN H EFI (1997)
Ignition Control Module: Description and Operation
Ignition Control Module
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. Based on input signals, the PCM will signal the ICM 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 Exhaust Gas Recirculation (EGR)
flow rate.
