Jumper wire in fuse panel

[GreenMonkey]

I’ve got a jumper wire in my engine bay fuse panel and I’m not really sure why it was done. I don’t know much about electrical systems, but trying to get things cleaned up and corrected. Thought y’all might know what was going on and how I could correctly fix this. Attached is a pic of the jumper wire and a panel diagram. Truck is a k3500 with 7.4/nv4500 if that has any relevance. Thanks for any help you can provide.

 

[Orpedcrow]

See if you can pop that relay out and see which pin that wire is tapped into. 85,86,87,87a or 30.

 

[xXxPARAGONxXx]

Can you see if that wire travels beneath the [yellow 20A] fuse and out the bottom of the fuse box? We can see that one end of the wire is apparently connected to the brake lamp relay.

(Make sure you disconnect battery while you are working on that.)

 

[JOHNGAAA1]

Is is for the brake controller??

 

[GreenMonkey]

The wire is going to the 30 pin on the relay. I will get out there later tonight and see if it’s exiting the fuse panel underneath. The other end of the wire is going into the heated mirror fuse location. I realized my pic didn’t show that very well in, case that makes a difference.

 

[Orpedcrow]

The 30 pin is usually used as the “output”. Is there a trailer brake controller?

 

[GreenMonkey]

The 30 pin is usually used as the “output”. Is there a trailer brake controller?

There was a trailer brake controller on the truck. I took it out and plan to install a new one at some point. Didn’t think about that.

 

[Orpedcrow]

You may find it dangling through the firewall somewhere