Troubleshooting 73 Dart Slant 6 not starting.

The electronic box is a switch that replaces the points. Anytime the key is in "run" and a working system gets power, the coil draws current as if the points were closed. When the distributor triggers the box, it turns off the coil for a short length of time, and this is what forms the spark.

Turn key to "run." Measure voltage from coil + to ground. It should NOT be full battery voltage, but, rather, about 5--8 or maybe 10V

If coil is at full battery voltage with key in "run" this indicates either the coil is bad (open), a wiring error or problem, bad connection at the ECU connector, or that the ECU is not grounded, or that the ECU is bad

Turn key to "start" while watching meter. Coil + should be close to battery voltage.

Separate distributor pickup connector. Take the end to the harness, not the distributor. Tap the bare terminal on ground, while having a spark gap rigged to coil +, and with key in "run." Each "tap" should make a nice snap single spark. use something else for a wire out of the coil tower instead of the coil wire, as it may be bad, as well