1975 Plymouth duster brake relay question?

flathead31coupe said
That's what the wiring harness looks like if you unwrap it. That's been unwrapped so I can trace down wiring and find out where things go. Kind of like that when I got it but everything works and it runs. I was just questioning that relay. I didn't think the outside wire by itself went from that relay down to the proportioning valve. So where it came out of the number m spot on the middle bulkhead connector that goes to the dash brake light. I just tied on to that and ran it down to the switch on the proportion valve. I left everything else. Stay the same on the relay

Yes, I am fully aware of what a wire harness looks like if you unwrap it. What you've got there is not good, but hey, it's your car so do whatever.

It sounds like you're talking about the black wire then. That's the power feed wire, just because one end is connected to the brake pressure switch does not indicate that all of the items connected to it are for the brakes. You will find a black wire connected to almost every switch in the car, again, it's typically the power feed to the switch.

And as @67Dart273 said, your best course of action with that seat belt interlock relay is to bypass it, because it does not serve any purpose but it can and will disable your ignition if the relay or anything else in the interlock system fails.