[Bigblock50]

I had some time and made what I think is progress. As to the sparking when connecting the battery ... that seems to be generated by the aftermarket radio that’s connected to constant power. It has some kind of internal battery that wants charging. If you tap the battery post multiple times, it only sparks on the first tap. When I just left the battery fully connected, nothing bad happened. Turning on the ignition switch to “on” powered up the heater, wipers, etc.

That brings us back to the purple wire starting circuit. As reported above, when I started this repair job, I found that one of the purple wires had been spliced into by a PO and changed to a blue wire that went into a junction box. This meant that at the neutral safety switch, one terminal was hot when the ignition was “on,” but the other remained dead when the ignition was turned to start. I re-spliced that wire and took it to the solenoid per the original circuits. Today, when I was confident I didn’t have a short, I gave the ignition switch a try. Solenoid did not activate. Checking the two contacts at the neutral safety switch, it seems I now have the opposite situation. With the ignition switch “on,” both contacts are cold when one should be hot. With the ignition switch at “start,” one contact goes hot but not the other.

Underneath the dash, I see both 12ga purple wires leave the NS switch and run together behind the fuse box. But only one of these wires emerges through the bulkhead connector. Is that right? I can also see a 12ga purple wire at the back of the ignition switch. The factory wiring diagram is not all that helpful on where actual wires run and that’s the issue when a PO has rewired everything. I think the truck will start and run if I can get the other NS terminal to go hot with the ignition switch “on.”