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How to Wire 12 Volt Coils

by William Kinsey

Older-model cars used the 12-volt ignition coils to provide power to the spark plugs. These coils had very simple wiring. They usually required only three wires: the spark plug wire, the power wire and the ignition switch wire. Ignition coils of this type are usually a little larger than a soda can and are heavy because of the metal core and the field coil windings. These coils are also filled with oil for temperature control.

Step 1

Disconnect the black negative cable on the negative post of the battery.

Step 2

Look at the ignition coil. These coils have one large terminal for the spark plug wire that runs over to the distributor and two small terminals that supply power to the coil.

Step 3

Connect one end of the spark plug wire to the large center terminal of the ignition coil. Connect the other end of that wire to the center terminal of the distributor cap.

Step 4

Connect the positive terminal of the ignition coil to the "On" terminal of the ignition switch. Connect the negative terminal of the ignition coil to the coil terminal of the distributor.

Reconnect the negative battery cable to the negative post on the battery.

Items you will need

  • Socket wrench

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