A previous owner apparently used a trailer with lighting and the wire harness (small, inch or two wide) is now just hanging under the bumper, by a zip tie.

Is there any danger that water getting into the plug could cause a short or a blown fuse elsewhere?

Is it a good idea to cover or remove this now-unused wiring?

Thanks.

 

I would just make sure it is covered. That way you can keep all the crud out, and it will be easier to use when you need it. You wont have to clean it out.

 

The only danger in leaving it uncovered / dangling is if you plan in using it someday. If you don't ever plan on towing anything, leave it go. If you do, then you can end up with a problem. I leave mine plugged and coated with NPK Light Bulb Grease or Dielectric Grease - which are corrosion resistant. I've had problems in the past with trucks where leaving things uncovered and / or unprotected led to all sorts of corrosion in the running light slot. It shows up as a green powder - which happens to be all that's left of the conductor in that slot. My guess is that moisture leads to a (weak) complete circuit between that slot (hot with your lights on) and the ground - resulting in galvanic corrosion.

 

The uncovered wiring cannot cause a short or blown fuse as long as the terminals can't touch anything. In other words, it's okay to leave it uncovered.

If, sometime in the unforeseen future, you decide to use the trailer lights, three licks and a promise with a small toothbrush sized wire brush will clean any corrosion off.

It is also possible to put too much dilectric grease on, so that it will (a) attract dirt) and (b)prevent a good connection when you do hook up.

See, now we have proof that what they say about opinions is true...