Installing a headlight harness...
The only thing you're usually changing with a relay setup is the positive side of things. So the lights still need a good ground to function.
If you disconnected the ground, nothing would work until you re-attached it.
While you're there though, make sure the terminals and the surface under them is clean and tidy.
I usually scrape/sand/buff the metal, clean the connectors or replace them if they're too corroded, and then once it's all buttoned back up, spray a quick spritz of paint over the top to keep future rust to a bare minimum.
But as long as you just make sure the existing ones are clean, you're at least decent shape.
Paul







