I looked around a bunch on some threads to try to find a write up on disabling the function where your fog lights turn off when you turn on your high beams but write up after write up was only for the TJ. Here is how I disabled that function in a very simple way in my 94 YJ Sahara. I'm sure there are other ways, I just thought I would write mine up if anyone was interested.
The wiring harness is the original harness that came in my particular jeep however the lights themselves are not the original lamps.
I started by locating the relay that was clicking behind my gauge panel after removing my plastic cover and taking the gauge module out. I did that by turning on my lights and fog lights and then turning my high beams on and off to hear the fog lights turn on and off.
Then I dug out the harness that runs cross dash behind it. The factory fog lights have two relays, one that turns them on and off from the switch and one that turns them on and off as an interrupt when it receives voltage from the high beams switch. Your headlights do not have a relay in the cab so the only thing that you hear should be that relay.
Those relays look like this:
(You won't have a tab sticking out but that is one of the ones we will bend. More on that later.)
The relay on the left only has 4 of the 5 pins connected to anything even though there are 5 on the relay.
Here is that double plug with the relay I modified removed.
And here is the relay.
The outside pins in the row of 3 are the ones that talk to the high beams so I just bent them out so in the event I ever needed to turn that functionality back on.
And here it is taped to be certain it didn't contact anything back in the dash.
Then I just put it all back into the dash and reconnected everything.
I know there are a lot of conversations about whether or not this is legal or anything else, but this was just so that I have full control over my jeep. I understand that in fog you shouldn't have high beams on. It's just to have more light off the road so I can see further and the ground at the same time.
I don't like having any decisions made for me by my car.
Hope that is simple and helps anyone who was unsure about it.
Again, this is just my car, so there may be fluctuations model to model, but I think this is pretty standard for any and all 1994 YJ according to the service manual.