photo by Matt Wright, 2008. The secondary winding of your ignition coil delivers the spark to the distributor to be sent to the spark plugs. We'll test this part of the ignition coil second, for obvious reasons. If it's bad, you'll get a weak spark or no spark at all. To test the coil's secondary winding, attach the test probes to the outer 12V pole and the center pole (where the main wire goes to the distributor). The 12-volt pole is the spot where the power comes into your coil.