Ignition Switch Question "Pins"

[undertakerman]

I have a 68 F100 ignition switch from my truck and I was looking in my shop manual about the switch and saw the picture identifying which pin was what and it shows 2 pins called "Proof Pins" or "Prove Out Pins". What are they for, what do they do and what do they connect to.

[mrollings53]

One of them connects to a purple wire at the pigtail that grounds the little light bulb above the parking brake. The light is the brake failure warning light. It comes on when the brake system fails front or rear. The distribution block will seal off the failed system and trip a switch that turns on the light. The prove out on the ignition lets you know that the bulb hasn't burnt out.

I think it also turns on the idiot lights when you're starting your truck. I have gauges though, so don't know for sure.

[undertakerman]

Hey thanks a lot for the information. I should have remembered from the last truck I had but I guess I just forgot. Thanks again.