What is the definition/purpose of the Prove Out terminals on a 78 ignition switch?

I have a chilton manual with the wiring diagram but the switch wires aren't labeled so I don't know which color goes to which terminal.

I understand the batt terminals, the starter terminal, and accessory 1 terminal. I figure that the wire runing to the module is one of the ignition terminals, and that the one going to the coil/starter relay/EGR is the other ignition, and the other one to the fuse box should be accessory 2, but the purple/white to the brake low lamp confuses me and again what is a prove out? Is that where the Purple/white goes?

 

You at least need a Haynes.

Maybe consider a Helm manual too?

I assumed it was the truck in your sig as I was already into the reply.

Sorry bout that.

 

Following mil1ion's diagram, the prove-out terminals make a temporary ground when in the start position to light some indicator lamps to show the bulbs are good.

 

That was one of the scenarios I came to for the Phase Out, thank you for providing the proof positive.

I got more concerned after reading a earlier post about a burnt out purple/white wire and was concerned I'd smoke the whole harness if I didn't verify, so I take it the phase out to the brake low switch is to check the light and the brake portioning valve is operated from another part of the switch?

Mil1ion thank you for the diagram, I will archive it for my truck, though I was asking about a 78 for my buddies bronco but the purple/white are the same according to my other diagram and the rest makes sense to me, unless there are enough wires for all 9 terminals on his switch. (2) Batt, (2) Ign, (2) Phase Out, (2) Acc., (1) Starter.

Funniest thing about this whole thing is my truck is gonna require so much more than one diagram cause it has a 71 460 in it with 71 ignition system and none of the emissions controls at least as far as I can tell. Knew I was in for trouble when the 86 diagram showed EEC and other things I don't have, but I do have a bunch of unconnected terminals and wires...LOL.

So I will begin filling the shelves with Haynes and where do I found Helm manuals.

 

Well, seeing as how Biscuit's inquiries into the '78's ignition switch wiring were for my benefit, I'll just say....

THANKS!!!

 

So Bob,

What exactly do you think you need ?


A wiring diagram for a points ignition for 71 ?

Or Duraspark wiring for a 71 ?


The pin out for the 78 switch is here