How Do You Test An Ignition Coil?
The ignition coil in your car is a relatively simple device. It consists of a few coils of large gauge wire (called a secondary winding) wrapped by another winding of small gauge wire with hundreds of turns (called a primary winding). When power is supplied to the primary winding, a magnetic field builds, and when the power is shut off, the collapsing magnetic field induces a voltage into the secondary winding. That voltage is what fires the spark plug. Remove the coil from the vehicle and place it on your work bench. To remove the coil simply disconnect the electrical plugs, and remove the hold down bolts. Be careful with the electrical plugs as they get brittle and tend to break. Test the coil primary winding by inserting a straight pin in each electrical connector for the primary winding. Then set your digital volt/ohm meter for ohms and place a lead on each of the straight pins. A reading of zero resistance, or of infinite resistance means the primary winding is bad and the coil sh
