MSD Tech: How to test or false trigger your MSD ignition
Remove the coil wire from the distributor cap. Position the terminal so it is about ¼-1/2 inch from a good ground source such as the head or intake manifold.
With the engine off, locate the trigger source wiring. This is either the White wire of the MSD or the two pin magnetic pickup connector. Disconnect the wire that you are using from the distributor. Next turn the ignition key to the on position – do not crank the car.
If you are using the White wire to trigger the ignition, tap the white wire to ground quickly several times. A spark should jump from the coil wire to ground.
If you are using the two pin magnetic pickup, use a paperclip or wire to short the two wires, violet and green, together and apart quickly. Repeat this procedure rapidly. Each time the connection is broken, a spark should jump across the coil wire to ground.
If there is a spark, the coil and the ignition are working properly. If there is not spark, it is recommended to replace the coil and repeat the test. If there is still no spark, confirm that the ignition is receiving 12 volts on the small red wire, as well as on the heavy gauge Red wire. Also verify a quality ground. If the wiring checks okay, the ignition box will need to be repaired.