Theory Of Operation
WARNING: This page is about a different car, the 2015 Fiat 500. However, it is still accessible from the selected car via links, so may be relevant.
The purpose of this diagnostic monitor is to verify that each coil-on-plug Ignition Coil has achieved a sufficient burn. The primary winding of the Ignition Coils are supplied 12 volts from the Fused Automatic Shut Down (ASD) Relay Output circuit. The Powertrain Control Module (PCM) completes the ground circuit (low side driver) allowing the energy to build the magnetic field of the primary coil. The PCM will open the low side driver to allow the magnetic field to collapse to the secondary winding and be transferred to the spark plug. The PCM determines spark timing by monitoring engine operating parameters from the inputs of various sensors and then calculating the appropriate moment to initiate the spark event.