Ignition Coil: Operation
The Ignition Coils are powered by Fuse 11 in the Underhood Accessory Fuse Block. The Powertrain Control Module (PCM) controls the current flow through the primary side of the coils by toggling the control circuits. The secondary voltage is generated when the primary current flow stops, and the magnetic field created by the current flow in the primary windings collapses. The collapsing magnetic field induces a voltage into the secondary windings and creates a high voltage surge that is sent to the spark plug wire.
Each cylinder has a double coil set, and its own dedicated spark plug wire. The coils are controlled by the PCM. The coils can be fired simultaneously or in phases. The coils are phase-shift triggered, firing plugs A-B, then B-A, then A-B etc. The offset between the plug firing varies from 0° to 10°. Timing can be retarded by as much as 14.5°.