Trailer brake controller help!!

[THE-HOG]

1975 w100, 5.2, no radio, no ac, no power nothing. My under dash harness went kapooie, new under dash has no wires for the brake controller & the brake controller had previously been disabled. How can I put a nut on / block / seal the hydraulic line that goes through the firewall so I don't have to have the ugly box I don't need under my dash and it doesn't spit an ounce of fluid at me.

 

[65 sporty]

Remove the line where it's tied in, usually at the master. If it has a tee, remove it and put the original line back into the master. If not get a line nut or plug to cap off the line