This started a long while back and I've been meaning to get to it. One day both my highbeams died, got a new multifunction switch and no fix. Then one day for about a month they worked, died again, and that happened about twice and they haven't worked since. Could it be the headlamp switch, or maybe just a loose wire/connection?

 

Year might help. Model too even though I am guessing an XJ.
And my first question is any chance the upgraded headlight harness was put on the Jeep?

 

See my sig, #1. It's where to start.

 

Ah my bad, it's an '01 XJ.

 

That is OK. Sometimes it matters. Sometimes not.
Do what BlueRidgeMark says in his sig.
I asked about the headlight harness upgrade cause I just went through my lights kinda not working.
Kinda here and there.
Turned out to be the relays in the harness.

 

Sorry, not following you there.

 

Can you get them to work if you hold the lever in the high beam position?

 

"Sig" = signature. The block of text at the bottom of each user's post, which never changes. Some of us use it to give advice on common problems. In my case, #1 is applicable. There is a link there. Click it, and all will be revealed!

 

Just a possibility, if viewing on mobile the signature isn't displayed.

 

Ah, I hadn't thought of that. All the more reason not to live on your phone.

 

Nope. Doesn't work either direction.

 

Hah true but it's handier than carrying a laptop. Thanks though, I give it a look.

 

I'm guessing your lo beams are perfectly fine, just hi giving you issues?