Disconnect the ignition coil output wire at the distributor cap.
Connect a spark plug to the end of the ignition coil output wire which you just disconnected.
Connect a ground wire to the threaded portion of the spark plug.
Disconnect the ignition coil ground wire from the negative terminal on the coil (Green Wire).
Connect one end of a ground wire to the ignition coil negative terminal.
Turn the ignition switch to the ON position.
Tap the other end of the ignition coil ground wire jumper on an good grounding point (for example the battery negative terminal) and look for sparks at the spark plug that correspond to the frequency of your tapping of the ground wire.
If you have a good spark at the spark plug, the ignition coil is good.
If you don't get a good spark, check for approximately 12 Volts from the coil positive terminal (black wire) to ground with the ignition switch in the ON position. You should also get approximately 12 Volts from the coil negative terminal (Green wire) to ground.
Ignition Coil Resistance Check
In addition to the test above, you may elect to perform an ignition coil resistance check as confirmation of the coil's condition.
- Check the ignition coil primary coil resistance by connecting an ohmmeter between the positive (Black wire) and negative (Green wire) terminals on the coil. The resistance should be 0.4 to 0.6 ohms.
- Check the ignition coil secondary coil resistance by connecting an ohmmeter between the coil output terminal and the ignition coil negative terminal. The resistance should be 5000 to 7200 ohms.