Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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°.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.