One dim headlight? bad wiring? bad relay?

It sounds like you may have a high resistance or open ground and the circuit is being competed through the bulb filament rather than directly to ground. If this problem wasn't apparent with the old bulb - try plugging it back in and see if the problem still exists.

This is a common problem for Dirty or Corroded connectors.

With emory paper (Fine Sand Paper) or a small wire brush, clean the terminal connections on your wiring harness. Of course make sure the switch is off without any power to the lights.

I would assume since the bulbs are new, the brass or aluminum male connectors should be nice and shiny. If not, polish those as well

Some Dielectric or silicon grease on the connectors will protect them for tarnishing again. Vasoline Petroleum Jelly will work also after you've cleaned them. Lightly, don't gob it on.

Ken is stable on the money! that head easy isn't grounding thats why the two aspects are lighting fixtures jointly. the low beam is employing the severe beam twine to apply for a temp floor! stable call Ken!