If the
factory type ignition passes the 1-spark test out of the coil tower, you can almost bet that the following items are ok; ECU,coil,ignition sw, and wiring to the ballast, and at least one side of a dual ballast; the side that feeds the ECU on a 5-pin system.
That just leaves 4 checks; 1) make sure the distributor driveshaft spins when the engine cranks,and 2) the trigger system, and 3) the secondary ignition system, and 4) the ballast resistor.
Trigger test;
There are two ways to test the trigger;in circuit and out. The out test is to check it's resistance and compare it to the spec, which might be 200 to 600 ohms,IDK, but more than 100 and less than 1000.
The second way and my favorite; is to pull it off the plate and pass anything iron across the magnet, in either direction, to simulate the reluctor. With the ignition in run, a stream of sparks should issue from the coil tower wire to near ground. The dizzy can stay in the hole. Another way is to pop the reluctor off, and again excite the trigger with an iron/steel screwdriver.
Not having sparks does not mean for sure the trigger is dead. Yes it still could be the coil or even the ECU.
There is a third test but you will need an old analog multi-meter. You can check the actual signal output across the two wires by putting the meter to A/C millivolts, and exciting the trigger with the iron/steel screwdriver. Seeing the needle jump off zero in sync with the excitation,proves the trigger works.
Coil test;
The coil can be ohmed out. Again IDK the specs but here it is not critical. The primary side should be very low, like under 2 ohms but not shorted. The secondary side should be very high, like 7,000 times as much as the primary. so,Ima guessing around 10,000ohms. To see if it actually works you can just remove all wires from the coil, and jumper 12v to the + terminal and tickle the negative side to ground. I use a 15 inch coarse file laying on the intake and just drag a wire from the -side across it. As the wire makes and breaks contact a stream of sparks should issue from the secondary tower to near-ground.
The Ballast
Simple test is to ohm it out; both sides should be less than say 5 ohms-cold, but more than 1. I like to draw current through them using a signal light bulb. Bulb lights means ballast good.
ECU test
I'm not an electronics guy, but I've never had one pass the 1-spark test and fail to run the engine, unless it was poorly grounded.
Parting shots
I used to carry spares of the ballast and trigger and ECU, to solve by substitution, which is really fast, but fails to exercise my brain. But after many years of not needing anything other than the occasional ballast,I started carrying only that guy.I currently have 17 years on the big yellow Accell coil, so I can highly recommend that bad boy. If it turns out you need a trigger;be advised to replace it with one having the same colored wires, one of which is usually orange.I have seen a reverse polarity trigger with no Orange wire(I think it was gray). The reluctor will fire from zero gap to about .030, so don't panic to get it exactly at .008. I have been running .011 for decades, which means as the bushings in the dizzy wear out, my spark still works.When all else fails pull some current through the blue coil wire by connecting a known-to-work signal bulb up to it. Sometimes a splice, or a connection somewhere (often at the ballast) goes bad.There are two splices; one inside the car up above the column, and another along the firewall. The bulkhead connectors are also a known trouble-spot.If you are having other electrical issues too, then check the wires at the back of the ammeter;with the battery disconnected! They occasionally come loose over time
I think Del (67Dart273) made a thread or even a sticky on this stuff
Good luck
