According to, https://www.carparts.com/classroom/ignition.htm . I have two wires that go to positive side of coil, one from resistor / ballast and the other from ignition switch, is this correct? My question is, what is the expected voltage supposed to be when key is in ON position and expected voltage when cranking on these 2 positive wires? I am working on a truck that will not produce spark. Orange positive wire to coil has 10v when its in ON position and the other black positive cable(I assume is a resistor) has 1v. I do not remember how much it had when cranking, but I believe it was 12v, I will double check on that. Could I be missing voltage and thus causing no spark?
The “standard” or at least early versions of ballasted coil ignition systems had a resistor that dropped the voltage supplied to the coil to 6v or 9v so a 6 or 9v coil was used.
On starting, that resistor was by-passed so the coil was supplied with 12v, basically to help provide a better spark when the battery was under load from the starter. The battery voltage does tend to drop a bit when the starter is operated.
The 12v starting supply was either via a second wire from the ignition switch or from a terminal on the starter motor - usually from the starter as that was a shorter cable run...