Ballast resistor wiring

One way to think about this circuit, is that, other than the ADDED wiring to power the box 12V and the power to the second half of the resistor--which powers just part of the box, is that the run and bypass wiring IS THE SAME as if it had breaker points.

THIS MEANS that regardless of whether you have points or ECU, you should be able to do this:

1...With points, turn the key to run, and be sure the points are CLOSED. With current thus flowing in the coil, measure coil + V to ground. The V should NOT be full 12V but rather quite low, maybe 6--8V. This varies.

WITH ELECTRONIC, this measurement should be about the same. This measurement shows that the "run" circuit through the coil is intact and going through the resistor.

2...With the coil secondary wire grounded, and a meter again from coil + to ground, crank the engine WITH THE KEY and observe the cranking V at coil+. Ideally this should be "same as battery" but likely will be a bit low. It should be at least 11V or more with a good battery. This shows the IGN2/ bypass circuit is correctly wired to the coil.

Observe the "U" cutout on the ceramic resistor block. This was a "key" to the original connectors so that it could not be wired incorrectly. If you look closely at the diagram posted, and orient your resistor as shown, that will guide you as to wire placement.

Notice, EG that the two terminals on the "U" cutout end are jumpered and go to the "run" key circuit.

Also note in the diagram that the IGN2 connection is shown connected to coil +. This will function fine, but physically, is not how the factory was done. The brown IGN2 was always branched in at the coil + wire right at the ballast. The only reason I mention this, is that on an OEM harness, this makes it easy to ID the coil+ wire

Keep in the back of your mind, that you may have a bad terminal in the bulkhead connector, either for the IGN1 or 2, or even a problem in the ignition switch contacts or the switch connector

In an intermittent situation sometimes I recommend running a length of scrap wire temporarily to the affected circuit, and hook that either to a pilot lamp or meter so you can keep your eye on it.