brake prop valve sensor??

I just recently did the 95+ booster swap, and have been double checking all the connections recently for leaks, etc. On the prop valve theres been some fluid and it looks like its come from the sensor on the valve, as I undid it when swapping the booster. I only started tightening it and it snapped off.

What does this do, and is it necessary for the system to work? I drove it around the neighborhood and didn't notice any fluid coming out of it so I'm stumped.

Thanks in advance!

edit: this one:

IIRC, that switch will sense the difference between the front & rear braking circuits. If there's a difference, the red brake indicator should light up on the dash.

Come to think of it, mine (94 XJ) doesn't even have that switch anymore, I've got a Wilwood adjustable prop valve.

Thanks for the response! I dont even think the lights on my dash work. Could I just plug it up?

I haven't even noticed any fluid leaking from it yet, but I know it was leaking before the piece broke off.....

I can't think of any reason plugging it wouldn't work. You would lose the warning light in the dash, though. The trick would be finding the right threaded plug to fit. It might actually be easier to just buy a new switch.

idk at advance auto they have plugs, like you said though, just need to find the right size. Thanks for the replies, I doubt after 20 years the warning light even works anymore (like half the stuff in the jeep ).