99 SD 5.4l, while trying to track down a no crank situation I've been testing the ignition switch. I found a pin diagram online 1983 Ford Bronco Diagrams picture | SuperMotors.net (switch SW5011 is the same p/n for my truck) and everything checks out, except I have continuity in Start between P1 and P2. I'm not so clued up on electrics, they are described as proof 1 and proof 2, does anyone know what these pins are? Since they are apparently not supposed to have continuity (unless the diagram is wrong) could this prevent start signal from leaving the ignition switch?

 

They have extra terminals in the switch that run to some of the warning lights in the dash and ground. When you turn the switch to start, these terminals ground some of the warning light wires for a bulb test.

You should only be worried about the red/blue wire. Power usually comes in on the yellow wire(s) and when the switch is sprung to start, there should be power on the red/blue.

 

Terminals P1 and P2 are not used in your application, ignore them. Terminals B4 - STA (continuity in START) are what's used.

Did you check fuse F20 for HOT IN START? You need to half-split the circuit so you know where to focus your attention.