1974 Ford Bronco No Spark

[Nasty62]

My elderly friend has a 74 Ford Bronco and no spark is coming from the coil. The wiring is a mess and I really don’t know where to start. Here’s what I know: the battery is running 12v. The positive wire to the coil is 11.89v with key on. Zero voltage with key off. There’s a wire going from the electronic ignition to the negative side of the coil and it does not show ground. If I jumper from the battery to the negative coil side and then test voltage between the negative and positive coil posts, I get about 5.6v. Does anyone have any advice on how to diagnose the issue? Thanks in advance.

 

[Broncobowsher]

The coil sounds right. The voltage drop via the ballast resistor.
Is this a Duraspark ignition?
I would check for AC voltage at the pickup coil (purple and orange wires, or was one green?) while cranking the engine. This is a good mid point in the system to minimize chasing everything.