How to Check the Spark on an Ignition Coil

1. Disconnect the negative, or black, battery cable.
2. Locate the coil pack, using the car's manual to help. It should be located on, or be connected to, the main engine block. Disconnect the wire from the coil pack terminal and unplug the coil pack from the spark plugs.
3. Place the coil pack on a work surface with the connectors facing upward. Using the ohmmeter, test the coil's primary resistance by connecting the meter's red cable to the coil's positive connector and the black cable to the negative connector. The resistance reading should be between about 0.4 and 2 ohms.
4. Test the secondary resistance by connecting the red cable to the coil pack's terminal connector. Leave the black cable connected to the negative connector. The resistance reading should be between 6,000 and 15,000 ohms.
5. Replace your coil pack if either of the readings are outside the usual range.