Jeep MUX/T TOW circuit draining battery

My father has a 1995 Jeep grand Cherokee that drains the battery every few days. I draw tested the battery and it is fine. The alternator is charging fine. During a check of the circuits for battery drain, I found that the MUX/T Tow 50 amp fuse is draining the battery at a rate of about 1.5 amps or more. The manual I have does not list the fuse so the following questions come to mind.

1. What circuits are on this fuse?

1. Can the truck be safely operated without this circuit?

2. What further can you do to detect the trouble?

Some answers I came up with after a little more checking.

1. The gage cluster does not work when the fuse is removed, it must be on this fuse. None of the cluster system lights come on when this fuse is out. The cluster illumination lights work ok.

1. All external lights work without the fuse in except stop lights.

2. All other functions are working without the fuse in.

1. No the truck cannot be safely operated. See answer #1and 2 above

2. Found online that a check of any trouble codes might determine touble.

1. No codes were found. But i ddid have the battery cables off before this was checked. He is going to drive it home and back on Sat so I can recheck the codes.

2. Many replys to other posts here on this site refer to the MUX as a "multiplexer"

More questions

1. What the heck is a multiplexer?

1. What relay controls the cluster? Or is this done directly by the ECM.

I do have a good background in electrical and electronic circuits of many types, mostly radio and computer, but also including automotive. So feel free to beat me up if I am overlooking the obvious. I just feell like I am beating my head against the wall here.

Any help or ideas I have not persued would be greatly appreciated.

Thanks in advance.