Ignition Coil Repair - Get an online auto repair estimate
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The ignition (or spark) coil converts low battery voltage into the higher voltage needed to produce a spark with the capacity to ignite the gasoline in the engine. An engine can have one ignition coil or one ignition coil per cylinder.
Mechanics' Corner: More Technical Detail
The ignition coil is a small electrical transformer that converts the high amperage 12-volt output of the vehicle's electrical system into a low amperage but very high direct current (DC) voltage that ranges from 5,000 to 80,000+ volts. This is done with two sets of windings (primary and secondary) made up of very small, hair-like copper wire.
Primary Windings
Using the positive and negative terminals on the ignition coil, the primary windings are saturated with system voltage. As the energy in the primary windings surrounds the iron core, a strong magnetic field (or flux) is created. Once the primary windings are filled by current and/or when voltage-limiting devices activate to prevent the ignition coil from overheating, the flow of current to the coil is limited.
Secondary Windings
When the flow of current to the coil has been limited (by switching off the negative side of the coil), the stored energy collapses onto the grounded secondary windings (all electricity seeks ground in order to complete or balance a circuit). However, these secondary windings are vastly different from the primary windings because they have a much higher electrical resistance. This higher electrical resistance causes a transformation of the low voltage into a high voltage that electrically penetrates the secondary windings and finds the grounded path.
