Ignition Coil: Description and Operation

Fig. 4 Coil On Plug:

COIL ON PLUG
The engines are equipped with a coil on plug ignition system. Each cylinder has a dedicated coil that sits atop each plug. No secondary wires are required and connection from the coil to plug is made with a boot that is attached to the coil. The Powertrain Control Module (PCM) determines which coil to charge and fire at the correct time.

The Auto Shutdown (ASD) relay provides battery voltage to the ignition coil. The PCM provides a ground contact (circuit) for energizing the coil. When the PCM breaks the contact, the energy in the coil primary transfers to the secondary causing the spark. The PCM will de-energize the ASD relay if it does not receive the crankshaft position sensor and camshaft position sensor inputs.

The coil's low primary resistance (0.4 - 0.6 ohm) allows the PCM to fully charge the coil for each firing.

Fig. 5 Coil Capacitor:

Fig. 6 Coil Capacitor:

IGNITION COIL CAPACITOR
There is a coil capacitor added to each bank of cylinders.

These are for AM radio noise suppression.