So I noticed the other day that I had a brake leak. Went to looking around and found that there was a bolt plugging a hole in the soft line connection. I noticed that I had no"extra" connections or sensors hanging around. So I'm scratching my head trying to figure out what plugs into this connection. I bought a new soft hose and it to has an "extra" threaded connection. So my question is what connects here and is there any way to plug it off without damaging the flared threaded female connection?

 

My truck is a 1500 and yours is a 2500, but on my truck, that port has a line that runs across the truck to the front passenger brake caliper.

You seem to have an extra line on yours, in the picture, the line that's to the left of the bolt in question, where does that run? Does it run to your passenger side front brake caliper?

Again, my truck is a 1500, maybe they are supposed to be different there.

 

That's for 4 wheel abs, It looks like it was replaced not to long ago and the old plug was used. What does the other side look like?