You can test an engine coil or ignition coil by performing the bench test, which involves removing the primary and secondary windings, and then checking the correct resistance of the two windings. Another way of testing an engine coil is to use the spark plug test.Continue Reading
Start by referring to the service manual. Tie back any long hair, and remove loose clothing to avoid a possible fire outbreak.
For the bench test, remove the windings from the ignition coil and get correct resistance readings according to the manual. To check the primary winding resistance, connect the ohmmeter leads with the two side poles on the winding. To check secondary resistance, fix one lead to either of the poles and the other to the central high tension terminal. Correct readings range from 0.75 to 0.81 ohms and 10,000 to 11,000 ohms for the primary and secondary windings respectively. Replace the coil if the readings are inaccurate.
To perform a spark plug test, unplug the spark plug wire, while referring to the vehicle's manual if necessary, and detach the spark plug. Reconnect the wire with the plug, grasp the plug wire with pliers, with the uninsulated end touching the ground, and ignite the engine. A bright blue spark indicates that the coil is faultless. Replace the coil if the spark doesn't show.Learn more about Engine