Ignition Coil: Description and Operation

Fig.11 Ignition Coil:

The ignition coil assembly consists of 3 independent coils molded together. The coil assembly for these engines is mounted on the intake manifold. Spark plug cables route to each cylinder from the coil.

The coil fires two spark plugs every power stroke. One plug is the cylinder under compression, the other cylinder fires on the exhaust stroke. The Powertrain Control Module (PCM) determines which of the coils 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 magnetic energy in the coil 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. Refer to Auto Shutdown (ASD) Relay-PCM Output for relay operation.