Electronic Ignition System Diagnosis: Description

WARNING: This page is about a different car, the 2003 Pontiac Vibe. However, it is still accessible from the selected car via links, so may be relevant.

Each engine cylinder has a dedicated ignition coil assembly. The ignition coil assembly contains the ignition module circuitry. The power distribution circuit supplies system voltage to each coil assembly when the ignition switch is in the RUN or START positions. Each coil assembly regulates current flow through the primary coil windings, creating a magnetic field. The Powertrain Control Module (PCM) signals each coil assembly to supply a spark in a cylinder through a trigger circuit. Each assembly does so by opening the primary circuit coil, inducing a high voltage in the secondary circuit coil. The high voltage in the secondary circuit grounds by arcing at the spark plug. This event creates a pulse on the fail safe circuit that the PCM recognizes as a confirmation of spark.